Modern analytic chemistry

1400-Fm 9/9/99 7:37 AM Page i Chemistry Modern Analytical Chemistry David Harvey DePauw University Boston Burr Ridge, IL Dubuque, IA Madison, WI New York San Francisco St Louis Bangkok Bogotá Caracas Lisbon London Madrid Mexico City Milan New Delhi Seoul Singapore Sydney Taipei Toronto 1400-Fm 9/9/99 7:37 AM Page ii McGraw-Hill Higher Education A Division of The McGraw-Hill Companies MODERN ANALYTICAL CHEMISTRY Copyright © 2000 by The McGraw-Hill Companies, Inc All rights reserved Printed in the United States of America Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publisher This book is printed on acid-free paper KGP/KGP ISBN 0–07–237547–7 Vice president and editorial director: Kevin T Kane Publisher: James M Smith Sponsoring editor: Kent A Peterson Editorial assistant: Jennifer L Bensink Developmental editor: Shirley R Oberbroeckling Senior marketing manager: Martin J Lange Senior project manager: Jayne Klein Production supervisor: Laura Fuller Coordinator of freelance design: Michelle D Whitaker Senior photo research coordinator: Lori Hancock Senior supplement coordinator: Audrey A Reiter Compositor: Shepherd, Inc Typeface: 10/12 Minion Printer: Quebecor Printing Book Group/Kingsport Freelance cover/interior designer: Elise Lansdon Cover image: © George Diebold/The Stock Market Photo research: Roberta Spieckerman Associates Colorplates: Colorplates 1–6, 8, 10: © David Harvey/Marilyn E Culler, photographer; Colorplate 7: Richard Megna/Fundamental Photographs; Colorplate 9: © Alfred Pasieka/Science Photo Library/Photo Researchers, Inc.; Colorplate 11: From H Black, Environ Sci Technol., 1996, 30, 124A Photos courtesy D Pesiri and W Tumas, Los Alamos National Laboratory; Colorplate 12: Courtesy of Hewlett-Packard Company; Colorplate 13: © David Harvey Library of Congress Cataloging-in-Publication Data Harvey, David, 1956– Modern analytical chemistry / David Harvey — 1st ed p cm Includes bibliographical references and index ISBN 0–07–237547–7 Chemistry, Analytic I Title QD75.2.H374 2000 543—dc21 99–15120 CIP INTERNATIONAL EDITION ISBN 0–07–116953–9 Copyright © 2000 Exclusive rights by The McGraw-Hill Companies, Inc for manufacture and export This book cannot be re-exported from the country to which it is consigned by McGraw-Hill The International Edition is not available in North America www.mhhe.com 1400-Fm 9/9/99 7:37 AM Page iii Contents Contents Preface 2C.5 2C.6 Conservation of Electrons 23 Using Conservation Principles in Stoichiometry Problems 23 2D Basic Equipment and Instrumentation 25 2D.1 Instrumentation for Measuring Mass 25 2D.2 Equipment for Measuring Volume 26 2D.3 Equipment for Drying Samples 29 2E Preparing Solutions 30 2E.1 Preparing Stock Solutions 30 2E.2 Preparing Solutions by Dilution 31 2F The Laboratory Notebook 32 2G Key Terms 32 2H Summary 33 2I Problems 33 2J Suggested Readings 34 2K References 34 xii Chapter Introduction 1A 1B 1C 1D 1E 1F 1G 1H What is Analytical Chemistry? The Analytical Perspective Common Analytical Problems Key Terms Summary Problems Suggested Readings 10 References 10 Chapter Basic Tools of Analytical Chemistry 11 Numbers in Analytical Chemistry 12 2A.1 Fundamental Units of Measure 12 2A.2 Significant Figures 13 2B Units for Expressing Concentration 15 2B.1 Molarity and Formality 15 2B.2 Normality 16 2B.3 Molality 18 2B.4 Weight, Volume, and Weight-to-Volume Ratios 18 2B.5 Converting Between Concentration Units 2B.6 p-Functions 19 2C Stoichiometric Calculations 20 2C.1 Conservation of Mass 22 2C.2 Conservation of Charge 22 2C.3 Conservation of Protons 22 2C.4 Conservation of Electron Pairs 23 Chapter 2A The Language of Analytical Chemistry 35 18 3A Analysis, Determination, and Measurement 3B Techniques, Methods, Procedures, and Protocols 36 3C Classifying Analytical Techniques 37 3D Selecting an Analytical Method 38 3D.1 Accuracy 38 3D.2 Precision 39 3D.3 Sensitivity 39 3D.4 Selectivity 40 3D.5 Robustness and Ruggedness 42 3D.6 Scale of Operation 42 3D.7 Equipment, Time, and Cost 44 3D.8 Making the Final Choice 44 36 iii 1400-Fm 9/9/99 7:37 AM Page iv iv Modern Analytical Chemistry 3E Developing the Procedure 45 3E.1 Compensating for Interferences 45 3E.2 Calibration and Standardization 47 3E.3 Sampling 47 3E.4 Validation 47 3F Protocols 48 3G The Importance of Analytical Methodology 3H Key Terms 50 3I Summary 50 3J Problems 51 3K Suggested Readings 52 3L References 52 48 Chapter Evaluating Analytical Data 53 4A 4E.4 Errors in Significance Testing 84 Statistical Methods for Normal Distributions – 4F.1 Comparing X to µ 85 4F.2 Comparing s2 to σ2 87 4F.3 Comparing Two Sample Variances 88 4F.4 Comparing Two Sample Means 88 4F.5 Outliers 93 4G Detection Limits 95 4H Key Terms 96 4I Summary 96 4J Suggested Experiments 97 4K Problems 98 4L Suggested Readings 102 4M References 102 4F Characterizing Measurements and Results 54 4A.1 Measures of Central Tendency 54 4A.2 Measures of Spread 55 4B Characterizing Experimental Errors 57 4B.1 Accuracy 57 4B.2 Precision 62 4B.3 Error and Uncertainty 64 4C Propagation of Uncertainty 64 4C.1 A Few Symbols 65 4C.2 Uncertainty When Adding or Subtracting 65 4C.3 Uncertainty When Multiplying or Dividing 66 4C.4 Uncertainty for Mixed Operations 66 4C.5 Uncertainty for Other Mathematical Functions 67 4C.6 Is Calculating Uncertainty Actually Useful? 68 4D The Distribution of Measurements and Results 70 4D.1 Populations and Samples 71 4D.2 Probability Distributions for Populations 71 4D.3 Confidence Intervals for Populations 75 4D.4 Probability Distributions for Samples 77 4D.5 Confidence Intervals for Samples 80 4D.6 A Cautionary Statement 81 4E Statistical Analysis of Data 82 4E.1 Significance Testing 82 4E.2 Constructing a Significance Test 83 4E.3 One-Tailed and Two-Tailed Significance Tests 84 85 Chapter Calibrations, Standardizations, and Blank Corrections 104 5A Calibrating Signals 105 5B Standardizing Methods 106 5B.1 Reagents Used as Standards 106 5B.2 Single-Point versus Multiple-Point Standardizations 108 5B.3 External Standards 109 5B.4 Standard Additions 110 5B.5 Internal Standards 115 5C Linear Regression and Calibration Curves 117 5C.1 Linear Regression of Straight-Line Calibration Curves 118 5C.2 Unweighted Linear Regression with Errors in y 119 5C.3 Weighted Linear Regression with Errors in y 124 5C.4 Weighted Linear Regression with Errors in Both x and y 127 5C.5 Curvilinear and Multivariate Regression 127 5D Blank Corrections 128 5E Key Terms 130 5F Summary 130 5G Suggested Experiments 130 5H Problems 131 5I Suggested Readings 133 5J References 134 1400-Fm 9/9/99 7:38 AM Page v Contents Chapter Equilibrium Chemistry 135 6A Reversible Reactions and Chemical Equilibria 136 6B Thermodynamics and Equilibrium Chemistry 136 6C Manipulating Equilibrium Constants 138 6D Equilibrium Constants for Chemical Reactions 139 6D.1 Precipitation Reactions 139 6D.2 Acid–Base Reactions 140 6D.3 Complexation Reactions 144 6D.4 Oxidation–Reduction Reactions 145 6E Le Châtelier’s Principle 148 6F Ladder Diagrams 150 6F.1 Ladder Diagrams for Acid–Base Equilibria 150 6F.2 Ladder Diagrams for Complexation Equilibria 153 6F.3 Ladder Diagrams for Oxidation–Reduction Equilibria 155 6G Solving Equilibrium Problems 156 6G.1 A Simple Problem: Solubility of Pb(IO3)2 in Water 156 6G.2 A More Complex Problem: The Common Ion Effect 157 6G.3 Systematic Approach to Solving Equilibrium Problems 159 6G.4 pH of a Monoprotic Weak Acid 160 6G.5 pH of a Polyprotic Acid or Base 163 6G.6 Effect of Complexation on Solubility 165 6H Buffer Solutions 167 6H.1 Systematic Solution to Buffer Problems 168 6H.2 Representing Buffer Solutions with Ladder Diagrams 170 6I Activity Effects 171 6J Two Final Thoughts About Equilibrium Chemistry 175 6K Key Terms 175 6L Summary 175 6M Suggested Experiments 176 6N Problems 176 6O Suggested Readings 178 6P References 178 Chapter Obtaining and Preparing Samples for Analysis 179 7A The Importance of Sampling 180 7B Designing a Sampling Plan 182 7B.1 Where to Sample the Target Population 182 7B.2 What Type of Sample to Collect 185 7B.3 How Much Sample to Collect 187 7B.4 How Many Samples to Collect 191 7B.5 Minimizing the Overall Variance 192 7C Implementing the Sampling Plan 193 7C.1 Solutions 193 7C.2 Gases 195 7C.3 Solids 196 7D Separating the Analyte from Interferents 201 7E General Theory of Separation Efficiency 202 7F Classifying Separation Techniques 205 7F.1 Separations Based on Size 205 7F.2 Separations Based on Mass or Density 206 7F.3 Separations Based on Complexation Reactions (Masking) 207 7F.4 Separations Based on a Change of State 209 7F.5 Separations Based on a Partitioning Between Phases 211 7G Liquid–Liquid Extractions 215 7G.1 Partition Coefficients and Distribution Ratios 216 7G.2 Liquid–Liquid Extraction with No Secondary Reactions 216 7G.3 Liquid–Liquid Extractions Involving Acid–Base Equilibria 219 7G.4 Liquid–Liquid Extractions Involving Metal Chelators 221 7H Separation versus Preconcentration 223 7I Key Terms 224 7J Summary 224 7K Suggested Experiments 225 7L Problems 226 7M Suggested Readings 230 7N References 231 v 1400-Fm 9/9/99 7:38 AM Page vi vi Modern Analytical Chemistry Chapter Gravimetric Methods of Analysis 232 8A Overview of Gravimetry 233 8A.1 Using Mass as a Signal 233 8A.2 Types of Gravimetric Methods 234 8A.3 Conservation of Mass 234 8A.4 Why Gravimetry Is Important 235 8B Precipitation Gravimetry 235 8B.1 Theory and Practice 235 8B.2 Quantitative Applications 247 8B.3 Qualitative Applications 254 8B.4 Evaluating Precipitation Gravimetry 254 8C Volatilization Gravimetry 255 8C.1 Theory and Practice 255 8C.2 Quantitative Applications 259 8C.3 Evaluating Volatilization Gravimetry 262 8D Particulate Gravimetry 262 8D.1 Theory and Practice 263 8D.2 Quantitative Applications 264 8D.3 Evaluating Precipitation Gravimetry 265 8E Key Terms 265 8F Summary 266 8G Suggested Experiments 266 8H Problems 267 8I Suggested Readings 271 8J References 272 Chapter Titrimetric Methods of Analysis 273 9A Overview of Titrimetry 274 9A.1 Equivalence Points and End Points 274 9A.2 Volume as a Signal 274 9A.3 Titration Curves 275 9A.4 The Buret 277 9B Titrations Based on Acid–Base Reactions 278 9B.1 Acid–Base Titration Curves 279 9B.2 Selecting and Evaluating the End Point 287 9B.3 Titrations in Nonaqueous Solvents 295 9B.4 Representative Method 296 9B.5 Quantitative Applications 298 9B.6 Qualitative Applications 308 9B.7 Characterization Applications 309 9B.8 Evaluation of Acid–Base Titrimetry 311 9C Titrations Based on Complexation Reactions 314 9C.1 Chemistry and Properties of EDTA 315 9C.2 Complexometric EDTA Titration Curves 317 9C.3 Selecting and Evaluating the End Point 322 9C.4 Representative Method 324 9C.5 Quantitative Applications 327 9C.6 Evaluation of Complexation Titrimetry 331 9D Titrations Based on Redox Reactions 331 9D.1 Redox Titration Curves 332 9D.2 Selecting and Evaluating the End Point 337 9D.3 Representative Method 340 9D.4 Quantitative Applications 341 9D.5 Evaluation of Redox Titrimetry 350 9E Precipitation Titrations 350 9E.1 Titration Curves 350 9E.2 Selecting and Evaluating the End Point 354 9E.3 Quantitative Applications 354 9E.4 Evaluation of Precipitation Titrimetry 357 9F Key Terms 357 9G Summary 357 9H Suggested Experiments 358 9I Problems 360 9J Suggested Readings 366 9K References 367 Chapter 10 Spectroscopic Methods of Analysis 368 10A Overview of Spectroscopy 369 10A.1 What Is Electromagnetic Radiation 369 10A.2 Measuring Photons as a Signal 372 10B Basic Components of Spectroscopic Instrumentation 374 10B.1 Sources of Energy 375 10B.2 Wavelength Selection 376 10B.3 Detectors 379 10B.4 Signal Processors 380 10C Spectroscopy Based on Absorption 380 10C.1 Absorbance of Electromagnetic Radiation 380 10C.2 Transmittance and Absorbance 384 10C.3 Absorbance and Concentration: Beer’s Law 385 1400-Fm 9/9/99 7:38 AM Page vii Contents 10C.4 Beer’s Law and Multicomponent Samples 386 10C.5 Limitations to Beer’s Law 386 10D Ultraviolet-Visible and Infrared Spectrophotometry 388 10D.1 Instrumentation 388 10D.2 Quantitative Applications 394 10D.3 Qualitative Applications 402 10D.4 Characterization Applications 403 10D.5 Evaluation 409 10E Atomic Absorption Spectroscopy 412 10E.1 Instrumentation 412 10E.2 Quantitative Applications 415 10E.3 Evaluation 422 10F Spectroscopy Based on Emission 423 10G Molecular Photoluminescence Spectroscopy 423 10G.1 Molecular Fluorescence and Phosphorescence Spectra 424 10G.2 Instrumentation 427 10G.3 Quantitative Applications Using Molecular Luminescence 429 10G.4 Evaluation 432 10H Atomic Emission Spectroscopy 434 10H.1 Atomic Emission Spectra 434 10H.2 Equipment 435 10H.3 Quantitative Applications 437 10H.4 Evaluation 440 10I Spectroscopy Based on Scattering 441 10I.1 Origin of Scattering 441 10I.2 Turbidimetry and Nephelometry 441 10J Key Terms 446 10K Summary 446 10L Suggested Experiments 447 10M Problems 450 10N Suggested Readings 458 10O References 459 Chapter 11 Electrochemical Methods of Analysis 461 11A Classification of Electrochemical Methods 462 11A.1 Interfacial Electrochemical Methods 462 11A.2 Controlling and Measuring Current and Potential 462 vii 11B Potentiometric Methods of Analysis 465 11B.1 Potentiometric Measurements 466 11B.2 Reference Electrodes 471 11B.3 Metallic Indicator Electrodes 473 11B.4 Membrane Electrodes 475 11B.5 Quantitative Applications 485 11B.6 Evaluation 494 11C Coulometric Methods of Analysis 496 11C.1 Controlled-Potential Coulometry 497 11C.2 Controlled-Current Coulometry 499 11C.3 Quantitative Applications 501 11C.4 Characterization Applications 506 11C.5 Evaluation 507 11D Voltammetric Methods of Analysis 508 11D.1 Voltammetric Measurements 509 11D.2 Current in Voltammetry 510 11D.3 Shape of Voltammograms 513 11D.4 Quantitative and Qualitative Aspects of Voltammetry 514 11D.5 Voltammetric Techniques 515 11D.6 Quantitative Applications 520 11D.7 Characterization Applications 527 11D.8 Evaluation 531 11E Key Terms 532 11F Summary 532 11G Suggested Experiments 533 11H Problems 535 11I Suggested Readings 540 11J References 541 Chapter 12 Chromatographic and Electrophoretic Methods 543 12A Overview of Analytical Separations 544 12A.1 The Problem with Simple Separations 544 12A.2 A Better Way to Separate Mixtures 544 12A.3 Classifying Analytical Separations 546 12B General Theory of Column Chromatography 547 12B.1 Chromatographic Resolution 549 12B.2 Capacity Factor 550 12B.3 Column Selectivity 552 12B.4 Column Efficiency 552 1400-Fm 9/9/99 7:38 AM Page viii viii Modern Analytical Chemistry 12B.5 Peak Capacity 554 12B.6 Nonideal Behavior 555 12C Optimizing Chromatographic Separations 556 12C.1 Using the Capacity Factor to Optimize Resolution 556 12C.2 Using Column Selectivity to Optimize Resolution 558 12C.3 Using Column Efficiency to Optimize Resolution 559 12D Gas Chromatography 563 12D.1 Mobile Phase 563 12D.2 Chromatographic Columns 564 12D.3 Stationary Phases 565 12D.4 Sample Introduction 567 12D.5 Temperature Control 568 12D.6 Detectors for Gas Chromatography 569 12D.7 Quantitative Applications 571 12D.8 Qualitative Applications 575 12D.9 Representative Method 576 12D.10 Evaluation 577 12E High-Performance Liquid Chromatography 578 12E.1 HPLC Columns 578 12E.2 Stationary Phases 579 12E.3 Mobile Phases 580 12E.4 HPLC Plumbing 583 12E.5 Sample Introduction 584 12E.6 Detectors for HPLC 584 12E.7 Quantitative Applications 586 12E.8 Representative Method 588 12E.9 Evaluation 589 12F Liquid–Solid Adsorption Chromatography 590 12G Ion-Exchange Chromatography 590 12H Size-Exclusion Chromatography 593 12I Supercritical Fluid Chromatography 596 12J Electrophoresis 597 12J.1 Theory of Capillary Electrophoresis 598 12J.2 Instrumentation 601 12J.3 Capillary Electrophoresis Methods 604 12J.4 Representative Method 607 12J.5 Evaluation 609 12K Key Terms 609 12L Summary 610 12M Suggested Experiments 610 12N Problems 615 12O Suggested Readings 12P References 620 620 Chapter 13 Kinetic Methods of Analysis 622 13A Methods Based on Chemical Kinetics 623 13A.1 Theory and Practice 624 13A.2 Instrumentation 634 13A.3 Quantitative Applications 636 13A.4 Characterization Applications 638 13A.5 Evaluation of Chemical Kinetic Methods 639 13B Radiochemical Methods of Analysis 642 13B.1 Theory and Practice 643 13B.2 Instrumentation 643 13B.3 Quantitative Applications 644 13B.4 Characterization Applications 647 13B.5 Evaluation 648 13C Flow Injection Analysis 649 13C.1 Theory and Practice 649 13C.2 Instrumentation 651 13C.3 Quantitative Applications 655 13C.4 Evaluation 658 13D Key Terms 658 13E Summary 659 13F Suggested Experiments 659 13G Problems 661 13H Suggested Readings 664 13I References 665 Chapter 14 Developing a Standard Method 666 14A Optimizing the Experimental Procedure 667 14A.1 Response Surfaces 667 14A.2 Searching Algorithms for Response Surfaces 668 14A.3 Mathematical Models of Response Surfaces 674 14B Verifying the Method 683 14B.1 Single-Operator Characteristics 683 14B.2 Blind Analysis of Standard Samples 683 14B.3 Ruggedness Testing 684 14B.4 Equivalency Testing 687 1400-Fm 9/9/99 7:38 AM Page ix Contents 14C Validating the Method as a Standard Method 687 14C.1 Two-Sample Collaborative Testing 688 14C.2 Collaborative Testing and Analysis of Variance 693 14C.3 What Is a Reasonable Result for a Collaborative Study? 698 14D Key Terms 699 14E Summary 699 14F Suggested Experiments 699 14G Problems 700 14H Suggested Readings 704 14I References 704 Chapter 15 Quality Assurance 705 15A Quality Control 706 15B Quality Assessment 708 15B.1 Internal Methods of Quality Assessment 708 15B.2 External Methods of Quality Assessment 711 15C Evaluating Quality Assurance Data 712 15C.1 Prescriptive Approach 712 15C.2 Performance-Based Approach 714 15D 15E 15F 15G 15H 15I Key Terms 721 Summary 722 Suggested Experiments 722 Problems 722 Suggested Readings 724 References 724 Appendixes Appendix 1A Appendix 1B Appendix 1C Appendix 1D Appendix 1E Appendix Appendix 3A Appendix 3B Appendix 3C Appendix 3D Appendix 3E Appendix Appendix Appendix Appendix Glossary Index Single-Sided Normal Distribution 725 t-Table 726 F-Table 727 Critical Values for Q-Test 728 Random Number Table 728 Recommended Reagents for Preparing Primary Standards 729 Solubility Products 731 Acid Dissociation Constants 732 Metal–Ligand Formation Constants 739 Standard Reduction Potentials 743 Selected Polarographic Half-Wave Potentials 747 Balancing Redox Reactions 748 Review of Chemical Kinetics 750 Countercurrent Separations 755 Answers to Selected Problems 762 769 781 ix 1400-Fm 9/9/99 7:38 AM Page x x Modern Analytical Chemistry A Guide to Using This Text in Chapter Representative Methods 246 Annotated methods of typical analytical procedures link theory with practice The format encourages students to think about the design of the procedure and why it works Modern Analytical Chemistry An additional problem is encountered when the isolated solid is nonstoichiometric For example, precipitating Mn2+ as Mn(OH)2, followed by heating to produce the oxide, frequently produces a solid with a stoichiometry of MnOx , where x varies between and In this case the nonstoichiometric product results from the formation of a mixture of several oxides that differ in the oxidation state of manganese Other nonstoichiometric compounds form as a result of lattice defects in the crystal structure.6 Margin Notes Margin notes direct students to colorplates located toward the middle of the book 110 Modern Analytical Chemistry either case, the calibration curve provides a means for relating Ssamp to the analyte’s concentration Representative Methods Representative Method The best way to appreciate the importance of the theoretical and practical details discussed in the previous section is to carefully examine the procedure for a typical precipitation gravimetric method Although each method has its own unique considerations, the determination of Mg2+ in water and wastewater by precipitating MgNH4PO4 ⋅ 6H2O and isolating Mg2P2O7 provides an instructive example of a typical procedure EXAMPLE 5.3 Color plate shows an example of a set of external standards and their corresponding normal calibration curve A second spectrophotometric method for the quantitative determination of Pb2+ levels in blood gives a linear normal calibration curve for which Sstand = (0.296 ppb–1) × CS + 0.003 What is the Pb2+ level (in ppb) in a sample of blood if Ssamp is 0.397? SOLUTION CA = 0.296 ppb –1 (NH4)2HPO4 as the precipitant The precipitate’s solubility in neutral solutions (0.0065 g/100 mL in pure water at 10 °C) is relatively high, but it is much less soluble in the presence of dilute ammonia (0.0003 g/100 mL in 0.6 M NH3) The precipitant is not very selective, so a preliminary separation of Mg2+ from potential interferents is necessary Calcium, which is the most significant interferent, is usually removed by its prior precipitation as the oxalate The presence of excess ammonium salts from the precipitant or the addition of too much ammonia can lead to the formation of Mg(NH4)4(PO4)2, which is subsequently isolated as Mg(PO3)2 after drying The precipitate is isolated by filtration using a rinse solution of dilute ammonia After filtering, the precipitate is converted to Mg2P2O7 and weighed Procedure Transfer a sample containing no more than 60 mg of Mg2+ into a 600-mL beaker Add 2–3 drops of methyl red indicator, and, if necessary, adjust the volume to 150 mL Acidify the solution with M HCl, and add 10 mL of 30% w/v (NH4)2HPO4 After cooling, add concentrated NH3 dropwise, and while constantly stirring, until the methyl red indicator turns yellow (pH > 6.3) After stirring for min, add mL of concentrated NH3, and continue stirring for an additional 10 Allow the resulting solution and precipitate to stand overnight Isolate the precipitate by filtration, rinsing with 5% v/v NH3 Dissolve the precipitate in 50 mL of 10% v/v HCl, and precipitate a second time following the same procedure After filtering, carefully remove the filter paper by charring Heat the precipitate at 500 °C until the residue is white, and then bring the precipitate to constant weight at 1100 °C Why does the procedure call for a sample containing no more than 60 mg of 0.397 – 0.003 = = 1.33 ppb 0.296 ppb –1 It is worth noting that the calibration equation in this problem includes an extra term that is not in equation 5.3 Ideally, we expect the calibration curve to give a signal of zero when CS is zero This is the purpose of using a reagent blank to correct the measured signal The extra term of +0.003 in our calibration equation results from uncertainty in measuring the signal for the reagent blank and the standards An external standardization allows a related series of samples to be analyzed using a single calibration curve This is an important advantage in laboratories where many samples are to be analyzed or when the need for a rapid throughput of l i iti l t ii l f th t l t d Examples of Typical Problems Each example problem includes a detailed solution that helps students in applying the chapter’s material to practical problems Determination of Mg2+ in Water and Wastewater7 Description of Method Magnesium is precipitated as MgNH4PO4 ⋅ 6H2O using Questions To determine the concentration of Pb2+ in the sample of blood, we replace Sstand in the calibration equation with Ssamp and solve for CA Ssamp – 0.003 Method 8.1 matrix matching Adjusting the matrix of an external standard so that it is the same as the matrix of the samples to be analyzed method of standard additions A standardization in which aliquots of a standard solution are added to the sample q y There is a serious limitation, however, to an external standardization The relationship between Sstand and CS in equation 5.3 is determined when the analyte is present in the external standard’s matrix In using an external standardization, we assume that any difference between the matrix of the standards and the sample’s matrix has no effect on the value of k A proportional determinate error is introduced when differences between the two matrices cannot be ignored This is shown in Figure 5.4, where the relationship between the signal and the amount of analyte is shown for both the sample’s matrix and the standard’s matrix In this example, using a normal calibration curve results in a negative determinate error When matrix problems are expected, an effort is made to match the matrix of the standards to that of the sample This is known as matrix matching When the sample’s matrix is unknown, the matrix effect must be shown to be negligible, or an alternative method of standardization must be used Both approaches are discussed in the following sections 5B.4 Standard Additions The complication of matching the matrix of the standards to that of the sample can be avoided by conducting the standardization in the sample This is known as the method of standard additions The simplest version of a standard addition is shown in Figure 5.5 A volume, Vo, of sample is diluted to a final volume, Vf, and the signal, Ssamp is measured A second identical aliquot of sample is Bold-faced Key Terms with Margin Definitions Key words appear in boldface when they are introduced within the text The term and its definition appear in the margin for quick review by the student All key words are also defined in the glossary x 1400-Indx 9/27/99 2:17 PM Page 786 786 Index ladder diagram for, 315, 315f metal-EDTA formation constants, 315 as titrant, 327 titration curves of, 317–322, 319f calculation of, 317–319, 319f sketching of, 320–322, 320t, 321f–322f as weak acid, 315 Effective bandwidth, 376 Effective diameters, of selected inorganic cations and anions, 173, 173t Ektachem analyzer, 493, 493f Elastic scattering, 441 Electrical double layer, 513 Electric field in capillary electrophoresis, 603–604 of plane-polarized electromagnetic radiation, 369, 369f–370f Electrochemical cell(s) potentiometric See Potentiometric electrochemical cells voltammetric, 510, 511f Electrochemical detectors, for highperformance liquid chromatography, 585, 585f Electrochemical methods, 461–531 bulk, 462 classification of, 462–465 coulometry, 496–508 current and potential in, control and measurement of, 462–465 interfacial, 462, 463f potentiometry, 465–496 voltammetry, 508–532 Electrochemical reversibility, 527–528 Electrode(s) auxiliary, 463 counter, 462 dropping mercury, 509, 509f enzyme, 484–485, 485f of the first kind, 473–474 gas-sensing, 484, 484f, 485t glass, 477–479, 478f, 479t hanging mercury drop, 509, 509f indicator, 462 metallic, 473–475 ion-selective, 322, 475 crystalline solid-state, 479–482, 481t glass, 477–479, 478f, 479t liquid-based microelectrode, 493, 494f solid-state, 479–482, 481t membrane See Membrane electrodes redox, 475 reference, 462–463, 471–473, 473f–474f saturated calomel, 472, 473f of the second kind, 474–475 silver/silver chloride, 473, 474f solid, 510, 510f standard hydrogen, 471–472, 472f static mercury drop, 509, 509f Electrodeposition, 205t, 210 Electrogravimetry, 234 Electrokinetic injection, 603 Electrolysis time, in controlled-potential coulometry, 498 Electromagnetic radiation, 369–372 See also specific types of radiation absorption of, 380–384 continuum or line sources of, 375, 375f particle properties of, 371–372 plane-polarized electric field of, 369, 369f–370f magnetic field of, 369, 369f sources of monochromatic versus polychromatic, 377–378 for spectroscopy, 375, 375t spectrum, Color Plate 9, 372, 372f wave properties of, 369–371, 369f Electron, conservation of, 23 Electron capture detector, 570, 570f Electronic transitions, between quantized energy levels, 382, 382t Electron pairs, conservation of, 23 Electron spin resonance spectroscopy, 373t Electron transfer, kinetics of, and faradaic current, 512 Electroosmotic flow, 598, 599f reversal of, in capillary electrophoresis, 605, 605f velocity, 599 Electropherogram, 597–598 Electrophoresis, 597–609 See also Micellar electrokinetic capillary chromatography (MEKC) capillary See Capillary electrophoresis capillary gel, 606–607 capillary zone, 604–606 Electrophoretic chromatography, 547, 547f Electrophoretic mobility, 598–599 Electrophoretic velocity, 598 Electrothermal atomizers, 36, 37f, 414–415, 415f Contract Laboratory Program protocol for, 48, 49f versus flame atomizer, 416 Elution, isocratic versus gradient, 582 Emission, 373–374 See also Atomic emission entries gamma-ray, 645, 645f of photons, energy level diagram for, 373, 374t spectroscopies involving, 373t, 423 Emission line, intensity of, 434–435 Emission spectrum, 374, 427, 427f versus excitation spectrum, 427 Empirical models, for response surfaces, 675–676 End point, 274 in complexation titration finding by monitoring absorbance, 324, 324f finding with visual indicator, 323–324, 323t selection and evaluation of, 322–324 in controlled-current coulometry, 500 finding of by derivative method 291–293, 291t, 292f by monitoring pH, 290–293, 291f–292f by monitoring temperature, 293–295, 294f using indicator, 288–290 in precipitation titrations potentiometrically, 354 using indicator, 354 in redox titrations potentiometrically, 339, 339f with visual indicator, 338–339, 339f, 339t selecting and evaluating of, 287–295 End point volumes for phosphate species, 308t and sources of alkalinity, 301, 302t Energy Gibb’s free, 137–138 SI and non-SI units for, 13t in spectroscopy chemical, 375 thermal, 375 Energy levels diagram of for absorption of photons, 372, 372f for emission of photons, 373, 374t for photon, 372, 372f electronic transitions between, 382, 382f, 382t Enthalpy, 137 Entropy, 137 Environmental pollutants See Pollutants Environmental Protection Agency, Contract Laboratory Program of See Contract Laboratory Program (CLP) Enzyme(s), 636 electrode, 484–485, 485f inhibition of, 638–639, 639f–640f turnover number of, 638 Enzyme-catalyzed reactions, 636–637, 637f maximum rate and Michaelis constant for, 638 Equation(s) charge balance, 159 Henderson-Hasselbalch, 169–170 mass balance, 159 Nernst, 146–147, 468–470 regression, 122–124, 124f van Deemter, 561 Equilibrium, 136, 136f chemistry, 135–175 problem-solving in, 156–167 thermodynamics and, 136–138 Equilibrium constant(s), 138 for acid-base titrations, 310–311, 310f and activity effects, 171–174 for chemical reactions, 139–148 for complexation reactions, 145 manipulation of, 138–139 thermodynamic, 172–173 in ultraviolet/visible spectroscopy, 407–409 in voltammetry, 528–530, 528f Equilibrium-density-gradient centrifugation, 207, 207f Equivalence point, 274, 287–288, 287f in redox titrations, 337–338, 338f 1400-Indx 9/27/99 2:17 PM Page 787 Index Equivalency testing, and standard method, 687 Equivalent, 17 Equivalent weights, 17 acid-base titrations and, 309–310 Eriochrome Black T, 323t Eriochrome Blue Black R, 323t Error(s) in both x and y, weighted linear regression with, 127 determinate See Determinate error(s) experimental, 57–64 indeterminate See Indeterminate errors measurement, 58–60, 59t, 495, 495t method, 58 personal, 60 residual, 118, 119f sampling, 58 in significance testing, 84–85 titration, 274 type 1, 84–85 type 2, 84–85 and uncertainty, 64 in y, 119–127, 126f Esters, acid-base titrimetric procedures for, 303, 303t Ethylamine, acid dissociation constant for, 734t Ethylenediamine, acid dissociation constant for, 734t Ethylenediaminetetraacetic acid (EDTA) See EDTA Excitation in atomic emission spectroscopy, 435 sources of, 437 spectrum, versus emission spectrum, 427 thermal, spectroscopies involving, 373t Exclusion limit, 595 Experimental errors and accuracy, 57–62 characterization of, 57–64 Exponential notation, prefixes for, 13t External conversion, 425, 425f External standardization multiple-point, 117, 117t single-point, 117 External standards, 109–110 in atomic emission spectroscopy, 438 in potentiometry, 486–487 Extraction(s), 205t See also Separation(s) continuous, 213–215, 214f countercurrent, 546 gas-solid, 213 liquid-gas, 214, 214f liquid-liquid See Liquid-liquid extraction microextractions liquid-liquid, 212, 212f solid-phase, 213, 567 in particulate gravimetry, 263–264, 263f solid-phase, 212–213, 212f, 213t between two phases, 212 using dithizone, 223, 223f of volatile organic compounds, 214 Extraction chromatography, 205t F Factor, 667 Factorial designs, for response surfaces, 676–682, 676f, 681f–682f Factor levels, 667 Fahrenheit scale, 13t Fajans’ method, 354, 355t Faradaic current, 510 applied potential and, 510–511 kinetics of electron transfer and, 512 mass transport and, 511–512, 513f Faraday’s law, 496 Fellgett’s advantage, 379 Ferrocyanide, solubility products for, 731t Ferroin, 339t Ferrous ammonium sulfate, 344 FIA See Flow injection analysis (FIA) Fiagram, 650, 650f–651f Fiber-optic probes, 391, 392f FID See Flame ionization detector (FID) Field blank, 710 Filter/filtration, 205t absorption, 376 crucible, 244, 244f photometer, 388, 389f in precipitation gravimetry, 243–244, 243f, 263 in spectroscopy, 376 First derivative titration curve, 291, 291t, 292f First-order reactions, 751–752, 753f Fisher’s least significant difference, 696 Fixed-time integral methods, 628 Flame in atomic emission spectroscopy, 435, 435f in spectroscopy, 375 Flame atomizers, 413–414, 414f versus electrothermal atomizers, 416 fuels and oxidants used in, 413, 414t Flame ionization detector (FID), 570, 570f Florence, T M., 524 Flow injection analysis (FIA) evaluation in, 658 instrumentation in, 651–654 phosphate determination by, 656–657 quantitative analysis using, 655–657 on clinical samples, 656, 656t on environmental samples, 655, 655t representative methods in, 656–657 theory and practice, 649–651, 649f–650f Fluorescence, 423, 425–426 natural, organic compounds with, 429–430, 430t x-ray, 373t Fluorescence spectroscopy atomic, 373t molecular, 373t evaluation in, 432–434 inorganic analytes in, 429, 429f, 430t instrumentation in, 427–428 organic analytes in, 429–430 quantitative applications using, 429–432 787 radiationless deactivation in, 424–425 spectra in, 424–427 sensitivity in, slit orientation and, 433, 433f standardizing method in, 431–432 Fluoride solubility products for, 731t in toothpaste, 489–490 in waters and wastewater, 395t, 396 Fluorine, standard reduction potentials for, 744t Fluorometer, 433–434 Fluoxetine, in serum, 588–589, 588f Fluxes, for decomposition of inorganic samples, 201, 201t Force, SI and non-SI units for, 13t Formality, 15–16, 16t Formal potential, 332–333 Formation constant(s), 144 cumulative, 144 metal-ligand, 739t–742t conditional, 315–316, 316t stepwise, 144 Formazin, preparation of, 444, 444f Formic acid, acid dissociation constant for, 734t Formula weight, 17 Fourier transform infrared spectrometer (FT-IR), 378, 393 and gas chromatography, 570–571 and polyvinylchloride, 381, 381f Freedom, degrees of, 80 Free ions, versus complexed ions, in potentiometry, 489 Frequency, 370 Fronting, in column chromatography, 555, 555f F-test, 87, 727t–728t comparing two sample variances, 88 FT-IR See Fourier transform infrared spectrometer (FT-IR) Fumaric acid, acid dissociation constant for, 734t Fundamental analysis, G Gallium, standard reduction potentials for, 744t Galvanostat, 464–465, 465f Gamma ray, 642 emission, 645, 645f Gas(es) properties of, 596t samples collection of, 195–196 preservation and preparation, 196 Gas chromatography, 563–578, 563f accuracy in, 577 and chromatic columns, 564–565 detectors for, 569–571 evaluation in, 577–578 Fourier transform infrared spectrometers and, 570–571 liquid-solid, 590, 590f mass spectrophotometers and, 570–571 mobile phase of, 563 precision in, 577 1400-Indx 9/27/99 2:17 PM Page 788 788 Index qualitative applications using, 575 quantitative applications using, 571–574 calculations in, 572–574 clinical analysis, 572 consumer goods, 572 environmental analysis, 571–572, 572f–573f petroleum industry, 572 representative methods in, 576–577 sample introduction in, 567–568 adjusting analyte concentration in, 568 injection of, 568, 569f preparing volatile samples, 567–568 scale of operation in, 577 selectivity in, 578 sensitivity in, 578 stationary phases in, 565–567, 566t, 567f temperature control in, 568–569 time, cost and equipment in, 578 Gas-liquid chromatography (GLC), 564 Gas-sensing electrodes, 484, 484f, 485t Gas-solid extractions, 213 Gaussian distribution See Normal distribution Gay-Lussac, Joseph Louis, 331 Geiger counter, 643 Gel permeation chromatography See Sizeexclusion chromatography General theory of separation efficiency, 202–205 Gibb’s free energy, 137–138 Glass electrodes, 477–479, 478f, 479t Glass ion-selective electrodes, 477–479, 478f, 479t Glassware, measurement errors for, 59t, 60 GLC See Gas-liquid chromatography (GLC) GLPs See Good laboratory practices (GLPs) Glucose, UV/visible spectroscopy analysis of, 397t Glutamic acid, acid dissociation constant for, 734t Glutamine, acid dissociation constant for, 735t Glycine, acid dissociation constant for, 735t Glycolic acid, acid dissociation constant for, 735t GMPs See Good measurement practices (GMPs) Gold, standard reduction potentials for, 744t Good laboratory practices (GLPs), 706 Good measurement practices (GMPs), 706–707 Grab sample, 185, 197, 197f Gradient elution, 558, 558f versus isocratic elution, 582 Gran plot, 292f, 293, 294t Graphite furnace atomic absorption spectroscopy See Electrothermal atomizers Gravimetry, 232–265 electrogravimetry, 234 importance of, 235 and nickel, 2–4, 3f–4f overview of, 233–235 particulate See Particulate gravimetry precipitation See Precipitation gravimetry thermogravimetry, 255–257, 256f as total analysis technique, 38 types of, 234 volatilization See Volatilization gravimetry Gross sample, 193 Guard columns, 579 Hypothesis alternative, 83 null, 83 H ICP torch See Inductively coupled plasma (ICP) torch Ideal gas law, 149 Identification, limit of, 95–96, 95f IEC See Ion-exchange chromatography (IEC) Impurities in precipitate gravimetry, 238–240 types of, 238–239 Incident radiation, in spectroscopy based on scattering, 443 Inclusion, 238–239, 239f Inclusion limit, 593, 595 Indeterminate errors, 62 error and uncertainty, 64 evaluation of, 63, 63f, 63t sources of, 62–63, 63f in UV/vis and infrared spectroscopy, 410–411, 410t, 511f Indicator(s), 274 in acid-base titrations, 278 finding end point with, 288–293, 289f–290f, 289t pH ranges of, 288–290, 289f–290f, 289t in complexation titration, 323–324, 323t electrodes, 462 metallic, 473–475 metallochromic, 315, 323, 323t mixed, 289t in precipitation titrations, 354 redox, 338–339, 339f, 339t screened, 289t universal, Color plate Indigo tetrasulfonate, 339t Inductively coupled plasma (ICP) torch, 435, 435f detection limits of, 437, 437t Inflection points, in acid-base titration, 287–288, 290–291 Infrared radiation, versus UV/visible, absorption of, 381, 381f Infrared spectroscopy, 373t, 388–412 attenuated total reflectance cell for, 393–394, 393f instrument designs for, 393–394, 393f and molecules and polyatomic ions, 381, 381f and relative uncertainty in concentration, 410–411, 410t, 411f Inhibition, of enzymes, 638–639, 639f–640f competitive, 639, 640f noncompetitive, 639, 640f uncompetitive, 639, 640f Initial rate method, 753 Injection See also Flow injection analysis (FIA) electrokinetic, 603 in flow injection analysis, 652 hydrodynamic, 602 loop, 584 on-column, 568 and slow injection analysis, 649–658 Half-life, 643 Hanging mercury drop electrode (HMDE), 509, 509f Headspace sampling, 567 Heat, SI and non-SI units for, 13t Henderson-Hasselbalch equation, 169–170 Heterogenous, 58 Heyrovsky, Jaroslav, 508–509 High-performance liquid chromatography (HPLC), 578–589, 579f chromatography columns used in, 578–579 detectors for, 584–586 evaluation in, 589 instrumentation in, Color Plate 8, 583–584 mobile phases in, 580–583, 581t preparing samples for, 586 quantitative applications using, 586–588, 587f calculations in, 586–588 representative method in, 588–589 sample introduction in, 584, 584f stationary phases in, 579–580 Histidine, acid dissociation constant for, 735t Histogram, 77, 79f HMDE See Hanging mercury drop electrode (HMDE) Homogenous, 72 Homogenous precipitation, 241–242 HPLC See High-performance liquid chromatography (HPLC) Hydrodynamic injection, 602 Hydrodynamic voltammetry, 513, 516–519 Hydrogen, standard reduction potentials for, 744t Hydrogen cyanide, acid dissociation constant for, 735t Hydrogen fluoride, acid dissociation constant for, 735t Hydrogen peroxide, acid dissociation constant for, 735t Hydrogen sulfide, acid dissociation constant for, 735t Hydrogen thiocyanate, acid dissociation constant for, 735t Hydroxide, solubility products for, 731t–732t Hydroxylamine, acid dissociation constant for, 735t 8-Hydroxyquinoline, acid dissociation constant for, 735t Hypobromous acid, acid dissociation constant for, 735t Hypochlorous acid, acid dissociation constant for, 735t Hypoiodous acid, acid dissociation constant for, 735t I 1400-Indx 9/27/99 2:17 PM Page 789 Index split, 568 splitless, 568 Inorganic analysis acid-base titrations in, 300–302, 301f, 302t complexation titrations in, 327–328 precipitate gravimetry and, 247–250, 248t–249t redox titrations in, 344–345 volatilization gravimetry in, 259 In situ sample, 185 Intensity, of emission line, 434–435 Intercellular fluids, analysis of, 493, 494f Interfacial electrochemical methods, 462 family tree for, 462, 463f Interference chemical, 438, 440 compensating for, in development of procedure, 45–46 masking and, 207–208 spectral, 418–419, 437–438, 438f Interferents, separation of analyte from, 201–202 Interferometers, 378–379, 379f Internal conversion, 425, 425f Internal standards, 115–117 in atomic emission spectroscopy, 438 Intersystem crossing, 425, 425f Iodate, solubility products for, 732t Iodic acid, acid dissociation constant for, 735t Iodide, solubility products for, 732t Iodine as oxidizing titrant, 346 protein-bound, 397t standard reduction potentials for, 744t Ion(s) anions effective diameters, 173, 173t selected gravimetric method for, 248, 248t cations effective diameters, 173, 173t selected gravimetric method for, 248, 248t–249t complexed versus free, in potentiometry, 489 inorganic chelating agents for in fluorometric analysis, 429, 430t controlled-potential coulometric analysis of, 501, 502t effective diameters, 173, 173t selected gravimetric method for, 248, 248t–249t metal, chelating agents for in fluorometric analysis, 429, 430t polyatomic, infrared spectrum of, 381 UV/visible spectrum for, 382–383 Ion exchange, 205t, 210 Ion-exchange chromatography (IEC), 547, 547f, 590–593, 594f Ion-exchange resin, 590–593, 591f, 591t Ionic strength, Color Plate 3, 172 Ionization suppressor, 420 Ionophore, 482 Ion-selective electrodes, 322, 475 crystalline solid-state, 479–482, 481t liquid-based, 482–484, 482f, 483t solid-state, 479–482, 481t Ion-suppressor column, 592–593 Iron controlled-current coulometry analysis of, 499, 500f standard reduction potentials for, 744t in waters and wastewater, 395t, 398–399 Isocratic elution, 582 versus gradient elution, 582 Isoleucine, acid dissociation constant for, 735t Isotope, 642 radioactive half-life of, 643 rate of decay for, 643 Isotope dilution, 646–647 Isotope-dilution mass spectrometry, 235 J Jacquinot’s advantage, 378–379 Job’s method See Method of continuous variations Jones reductor, 341 selected reductions using, 341, 342t Joule, 13t Joule heating, 601–602 Judgmental sampling, 184 K Kelvin, 12t Kilogram, 12t Kinetic methods, 622–658, 751–754 chemical, 623–642 Kirchhoff, Guystav, 412 Kjeldahl analysis, Color Plate 5, 302–303 Kodak Ektachem analyzer, 493, 493f Kovat’s retention index, 575 L Laboratory notebook, 32 Laboratory sample, 199 Ladder diagram(s), 150–155 for acid-base equilibria, 150–152, 151f for alanine, 163, 163f for buffer solutions, 170–171, 171f for complexation equilibria, 153–155, 153f–155f for EDTA, 315, 315f for oxidation-reduction equilibria, 155, 155f–156f Lanthanum, standard reduction potentials for, 744t Large-particle scattering, 441, 441f Law(s) Beer’s, 385–388, 385f–386f Faraday’s, 496 ideal gas, 149 Ohm’s, 463 rate, 624–635, 750–751 789 Lead in drinking water, 36–37, 37f standard reduction potentials for, 744t in waters and wastewater, 395t LeChâtelier’s principle, 148–150 Length, SI and non-SI units for, 13t Leucine, acid dissociation constant for, 735t Leveling, 296 Lewis, G N., 144 Liebig, Justus, 314 Lifetime, 423 Ligand, 144 metal-ligand formation constants, 739t–742t Light See Electromagnetic radiation Limiting current, 514 Limit of identification, 95–96, 95f Limit of quantification, 96 Linear regression and calibration curves, 117–127 determination of estimated slope and y-intercept by, 119 goal of, 118 residual error in, 118, 119f of straight-line calibration curves, 118, 119f uncertainty in, 120–122, 120f unweighted, with errors in y, 119–124 weighted with errors in both x and y, 127 with errors in y, 124–127, 126f Line sources, 375, 375f Lineweaver-Burk plot, 638, 639f Liquid(s), properties of, 596t Liquid-based ion-selective electrodes, 482–484, 482f, 483t Liquid-based ion-selective microelectrode, 493, 494f Liquid-gas extraction, 214, 214f Liquid junction potential, 470–471, 470f Liquid-liquid extraction, 212, 212f, 215–223, 216f extraction efficiency in, 219, 219f, 221, 221f improved methods for, 544–546, 545f involving acid-base equilibria, 219–221, 219f, 221f involving metal chelators, 221–223, 221f–222f partition coefficients and distribution ratios in, 216 Liquid-liquid microextractions, 212, 212f Liquid-solid adsorption gas chromatography (LSC), 590, 590f Liter, 12t Lithium, standard reduction potentials for, 744t Litmus, 289t Longitudinal diffusion, 560–561, 560f Loop injector, 584 LSC See Liquid-solid adsorption gas chromatography (LSC) Luminescence, molecular See Fluorescence spectroscopy, molecular; Phosphorescence spectroscopy, molecular Lysine, acid dissociation constant for, 735t 1400-Indx 9/27/99 2:17 PM Page 790 790 Index M Magnesium, standard reduction potentials for, 744t Magnetic field, plane-polarized of electromagnetic radiation, 369, 369f Magnetic resonance spectroscopy See Nuclear magnetic resonance spectroscopy Maleic acid acid dissociation constant for, 736t titration curve for, 288, 288f Malic acid, acid dissociation constant for, 736t Malonic acid acid dissociation constant for, 736t titration curve for, 288, 288f Manganese standard reduction potentials for, 744t in waters and wastewater, 395t Manifold, in flow injection analysis, 652, 652f–654f Masking, 205t, 207–208 separation techniques based on, 207–209 Masking agents, 208, 208t Mass conservation of, 22 and gravimetry, 234–235 instrumentation for measuring of, 25–26, 25f–26f separation techniques based on, 206–207 SI unit for, 12t using as signal, 233–234 Mass balance equation, 159 Mass spectrometer and gas chromatography, 570–571 for high-performance liquid chromatography, 585–586 Mass spectrum, 571 Mass transfer, and column efficiency, 560f, 561 Mass transport, and faradaic current, 511–512, 513f Matrix, 36 sample, 110, 110f Matrix matching, 110 Maximum holding times, for selected waters and wastewater parameters, 195, 195t Maximum rate, for enzyme-catalyzed reactions, 638 Mean, 54–55 See also t-test of populations, 79 sample, 88–93 Measurement(s), 36 of central tendency, 54–55 characterization of, in analytical data, 54–57 distribution of, 70–82 fundamental units of, 12, 12t–13t of range, 56 of spread, 55–57 of standard deviation, 56–57 uncertainty and in mixed operations, 66–67 in other mathematical functions, 67–68, 68t when adding or subtracting, 65–66 when multiplying or dividing, 66 of variance, 57 Measurement error, 58–60 in potentiometry, 495, 495t for selected equipment, 58, 59t Median, 55 Mediator, 500 MEKC See Micellar electrokinetic capillary chromatography (MEKC) Membrane potentials, 475–476, 476f selectivity of, 476 Membrane electrodes crystalline solid-state ion-selective electrodes, 479–482, 481t gas-sensing electrodes, 484, 484f, 485t glass ion-selective electrodes, 477–479, 478f, 479t liquid-based ion-selective electrodes, 482–484, 482f, 483t membrane potentials in, 475–476, 476f potentiometric biosensors, 484–485, 485f–486f, 486t in potentiometric electrochemical cells, 475–485 selectivity of membrane in, 476–477, 477f Meniscus, 28f, 29 Mercury standard reduction potentials for, 744t in waters and wastewater, 395t Metal-EDTA formation constants, 315 Metal ions, inorganic, chelating agents for fluorometric analysis, 429, 430t Metallic indicator electrodes, 473–475 Metal-ligand complex, stoichiometry of, 403–407, 406f Metal-ligand formation constants, 739t–742t conditional, for EDTA, 315–316, 316t Metallochromic indicators, 315, 323, 323t Meter, 12t Methionine, acid dissociation constant for, 736t Method, 36 standardization of, 106 Method blank, 45, 128–129, 128t–129t Method error, 58 Method of continuous variations, Color Plate 6, 404–406 Method of standard additions, 110–111, 111f–112f calibration curve for, 114–115, 114f and potentiometry, 488–489 Methylamine, acid dissociation constant for, 736t Methylene blue, 289t, 339t Methyl isobutyl ketone (MIBK), 224 Methyl orange, 278, 289t Methyl-phenyl polysiloxane, 566t Methyl red, 289t MIBK See Methyl isobutyl ketone (MIBK) Micellar electrokinetic capillary chromatography (MEKC), 606 Micelle, 606, 606f Michaelis constant, 637 for enzyme-catalyzed reactions, 638 Microdroplet apparatus, 311, 311f Microextraction(s) liquid-liquid, 212, 212f solid-phase, 213, 567 Microtitration, diffusional, 312, 312f Microwave spectroscopy, 373t Migration, 512 Migration time, in capillary electrophoresis, 600 Mixed indicators, 289t Mixtures, improved separation methods for, 544–546 Mobile phases, 546 in gas chromatography, 563 in high-performance liquid chromatography, 580–583, 581t in superfluid chromatography, 596, 597t Mobility electrophoretic, 598–599 total, 599–600 Mohr method, 354, 355t Molality, 18 Molarity, 15–16, 16t Mole, 12t Molecular absorption spectroscopy versus atomic absorption, 412 instruments used in, 388–394 Molecular-exclusion chromatography See Sizeexclusion chromatography Molecular fluorescence spectroscopy See Fluorescence spectroscopy, molecular Molecular phosphorescence spectroscopy See Phosphorescence spectroscopy Molecular photoluminescence spectroscopy See Photoluminescence spectroscopy Molecules infrared spectrum of, 381, 381f UV/visible spectrum for, 382–383 Mole-ratio method, 406, 406f Molybdenum, standard reduction potentials for, 745t Monensin, 92–93 Monochromatic source, or radiation, 377–378 Monochromator, 376, 378f in infrared spectrometers, 393 wavelength selectors using, 376–378, 378f Monoprotic acid, pH of, 160–163 Mossbauer spectroscopy, 373t Multicomponent samples, Beer’s law and, 386 Multielemental analysis, using atomic emission spectroscopy, 436, 436f Multiple-point standardization, 109 external, 117, 117t versus single-point standardization, 108–109 Multivariate regression, 127 Murexide, 323t 1400-Indx 9/27/99 2:17 PM Page 791 Index N Negatron, 642 Nephelometry, 441–445 applications of, 444–445 determination of concentration by, 443 precipitates used in, 443–444, 444t versus turbidimetry, 442 Nernst equation, 146–147 and potentiometric electrochemical cells, 468–470 Nessler’s method, for ammonia, 368 Nessler tubes, 368, 388 Neutral red, 289t Neutron activation, 645 analysis, 645–646 Newton, 13t Nickel gravimetric analysis of, 2–4, 3f–4f standard reduction potentials for, 745t Nitrate, in waters and wastewater, 395t Nitrilotriacetic acid, acid dissociation constant for, 736t Nitrogen, standard reduction potentials for, 745t Nitron, 249t Nitrous acid, acid dissociation constant for, 737t Nominal wavelength, 376 Nonaqueous solvents, acid-base titrations in, 294f, 295–296, 296f Noncatalytic reactions, 638 Noncompetitive inhibition, of enzymes, 639, 640f Nonenzyme-catalyzed reactions, 637–638 Nonfaradaic currents, 512–513 Nonideal behavior, in column chromatography, 555, 555f Normal calibration curve, 109, 109f effect of sample’s matrix on, 110, 110f Normal distribution, 73–75, 74f–75f single-sided, 725t–726t statistical methods for, 85–94 Normality, 16–18 Normal-phase chromatography, 580 Nuclear magnetic resonance spectroscopy, 373t Null hypothesis, 83 Numbers, in analytical chemistry, 12–15, 12t–13t Nyquist theorem, 184 O Occlusion, 239, 239f Octadecyl, 213t Octyl, 213t Ohm’s law, 463 On-column injection, 568 One-factor-at-a-time optimization, 669–671, 669f–671f One-tailed significance test, 84, 84f Open tubular columns See Capillary column Optimization one-factor-at-a-time, 669–671, 669f–671f simplex, 671–674, 671f, 673t, 674f–675f Organic analysis acid-base titrations in, 302–303 precipitate gravimetry and, 250, 250t redox titrations in, 346–347 volatilization gravimetry in, 259–260 Organic compounds, with natural fluorescence or phosphorescence, 429–430, 430t Outlier, 93–94 Overall variance, minimization of, 192–193 Overpotential, 497 Oxalate, solubility products for, 732t Oxalic acid, acid dissociation constant for, 737t Oxidant, used in flame atomizers, 413, 414t Oxidation, 146 Oxidation-reduction reactions See Redox reactions Oxidation state, of analyte, in redox titration, 341–342 Oxidizing agent, 146 auxiliary, 341 reaction units for, 23 Oxygen, standard reduction potentials for, 745t P Packed columns, 564 Paired data, 88, 91–93 Paired t-test, 92–93 PAN, 323t Particle(s) airborne pollutant, 7–8 alpha, 642 beta, 642 and large-particle scattering, 441, 441f properties of, in electromagnetic radiation, 371–372 radioactive, 642 size in precipitation gravimetry, 240–243, 242f reducing in solid samples, 199–200 separation techniques based on, 205–206 Particulate gravimetry, 234, 262–265 evaluation of, 265 extraction in, 263–264, 263f filtration in, 263 quantitative applications involving, 264–265 calculations in, 264–265 theory and practice, 263–264 Partition chromatography, 547, 547f Partition coefficient, 211–212 in liquid-liquid extractions, 216 Partitioning, between phases, separation techniques based on, 211–215, 212f, 213t Parts per billion, 18 Parts per million, 18 791 Pascal, 13t Peak capacity, 554–555 Peptization, 245 Performance-based approach, to quality assurance, 714–721 Peristaltic pump, 652, 652f Personal error, 60 p-function, 19–20 pH and acid-base titrations, 279 of buffer solutions, 169–170, 492t electrode, 290 of indicators in acid-base titration, 288–290, 289f–290f, 289t and finding end point, 290–293, 291f–292f of monoprotic weak acid, 160–163 potentiometric measurement of, 489–490 and precipitate solubility, 237 scale, 142–143, 143f uncertainty in, 67–68 universal indicator for, Color plate Pharmaceuticals, natural fluorescence and phosphorescence of, 430t Phenol, in waters and wastewater, 395t, 396 Phenolphthalein, 278, 289t Phenol red, 289t Phenylalanine, acid dissociation constant for, 737t Phosphate determination of, by flow injection analysis, 656–657 end point volumes for, 308t solubility products for, 732t in waters and wastewater, 395t Phosphorescence, 424, 426–427 natural, organic compounds with, 429–430, 430t Phosphorescence spectroscopy molecular, 373t evaluation in, 432–434 inorganic analytes in, 429, 429f instrumentation in, 428–429, 428f organic analytes in, 429–430 quantitative applications using, 429–432 radiationless deactivation in, 424–427 spectra in, 424–427 standardizing method in, 431–432 Phosphoric acid, acid dissociation constant for, 737t Phosphorus, standard reduction potentials for, 745t Photodiode array, 379 Photoluminescence, 374 Photoluminescence spectroscopy, 373t, 374, 374f, 423–434 accuracy in, 432 evaluation in, 432–434 excitation versus emission spectra in, 427, 427f 1400-Indx 9/27/99 2:17 PM Page 792 792 Index fluorescence and phosphorescence spectra, 424–427 inorganic analytes in, 429, 429f, 430t instrumentation in, 425f–426f, 427–429 organic analytes in, 429–430, 431t precision in, 432 quantitative applications using, 429–432 radiation deactivation in, 424–425, 425f scale of operation in, 432 sensitivity in, 432–433, 433f standardizing methods in, 431–432 time, cost and equipment in, 433–434 Photon(s), 371 absorption of, 372, 372f emission of, 373, 374t as signals, 372–374, 373f, 373t Photon transducers, 379, 380t Phthalic acid, acid dissociation constant for, 737t Physical state, changes in, separations based on, 209–210, 209t Piezoelectric effect, 263 Piperidine, acid dissociation constant for, 737t Pipet measurement errors for, 59t, 60 types of, 27–28, 27f–28f Planar chromatography, 546 Plasma, 435 as energy source, in spectroscopy, 375 sources in atomic emission spectroscopy, 435–436, 435f Plasma torch, inductively coupled, 435, 435f Platinum, standard reduction potentials for, 745t Polarity index, 580, 581t Polarographic half-wave potentials, 747t Polarography, 515–516, 515f–516f Pollutants aerosol, 7–8 natural fluorescence and phosphorescence of, 430t Polyatomic ions, infrared spectrum of, 381 Polychromatic source, of radiation, 377–378 Polydimethyl siloxane, 566t Polyethylene glycol, 566t Polyprotic acid, pH of, 163–165 Polyprotic base, pH of, 163–165 Polyvinylchloride, Fourier transform infrared spectrum of, 381, 381f Population(s), 71 confidence intervals for, 75–77, 75t degrees of freedom for, 80 mean and variance of, 79 probability distributions for, 71–75 Positron, 642 Potassium Kodak Ektachem analyzer for, 493, 493f standard reduction potentials for, 745t Potential(s) See also Controlled-potential coulometry asymmetry, 476 controlling and measuring of, in electrochemical methods, 462–465 formal, 332–333 liquid junction, 470–471, 470f membrane, 475–476, 476f polarographic half-wave, 747t of potentiometric electrochemical cells, 468–470 selection of, in controlled-potential coulometry, 497, 497f SI and non-SI units for, 13t standard reduction, 743t–746t standard-state, determining by voltammetry, 514–515, 515f zeta, 599 Potentiometer, 464, 464f Potentiometric biosensors, 484–485, 485f–486f, 486t Potentiometric electrochemical cells, 466–467, 466f membrane electrodes in, 475–485 metallic indicator electrodes, 473–475 potential and concentration of, 468–470 reference electrodes in, 471–473, 473f–474f shorthand notation for, 467–468 Potentiometric titrations, 494 Potentiometry, 465–496 accuracy in, 494–495 and concentration technique, 38 electrochemical cells in, 466–467, 466f evaluation of, 494–496 measurement error in, 495, 495t and measurement of pH, 489 measurements in, 466–471 precision in, 495, 495t quantitative applications using, 485–494 activity versus concentration, 485–486 clinical applications, 492–494 environmental applications, 494 free ions versus complexed ions, 489 potentiometric titrations in, 494 using method of standard additions, 488–489 representative method for, 489–490 scale of operation in, 494 selectivity in, 496 sensitivity in, 495 time, cost and equipment in, 496 using external standards, 486–487 Potentiostat, 465, 465f Power, SI and non-SI units for, 13t Precipitant, 235 Precipitate, 139 final, composition of, 245–246 in precipitation gravimetry drying of, 245 filtering of, 243–244, 243f rinsing of, 244–245 use in turbidimetry/nephelometry, 443–444, 444t Precipitation gravimetry, 234–255 accuracy in, 254 avoiding impurities in, 238–240 controlling particle size in, 240–243, 242f drying precipitate in, 245 evaluation of, 254–255 filtering precipitate in, 243–244, 243f final composition of precipitate in, 245–246 and inorganic analysis, 247–250, 248t–249t and organic analysis, 250, 250t qualitative calculations involving, 254 quantitative applications involving, 247–253 quantitative calculations involving, 250–254 representative method in, 246–247 rinsing precipitate, 244–245 solubility considerations in, 235–238, 236f–237f theory and practice, 235–247 Precipitation reactions, Color Plate 4, 139–140, 205t, 210–211 conservation of charge in, 22 reaction units in, 22 using coulometric titrations, 504, 504t Precipitation titration(s), 350–357 end point in potentiometrically, 354 selection and evaluation of, 354 using indicator, 354 evaluation of, 357 qualitative applications involving, 355–357 quantitative applications involving, 354–357 Precipitation titration curves, 350–353, 357f calculation of, 350–351, 352f, 352t sketching of, 352, 353f Precision control chart construction of, 717–718, 717t, 718f–719f subrange, 718, 719f Preconcentration, versus separation, 223–224 Prescriptive approach, to quality assurance, 712–714, 713f Preservation methods, for selected waters and wastewater parameters, 195, 195t Pressure, SI and non-SI units for, 13t Primary reagents, 106–107 Primary sample See Gross sample Primary standard buffers, pH of, 492t Primary standards, recommended reagents for, 729–730 Probability distributions for populations, 71–75 for samples, 77–80 Problem-solving, analytical approach to, 5–8, 6f Procedure, 36 calibration and standardization in, 47 compensating for interferences, 45–46 development of, 45–47 protocols in, 48 validation in, 47 Proficiency standards, 711 Proline, acid dissociation constant for, 737t Propagation, of uncertainty, 64–70 1400-Indx 9/27/99 2:17 PM Page 793 Index Propanoic acid, acid dissociation constant for, 738t Propelling unit, in flow injection analysis, 652 Property control chart, construction of, 715–716, 716f, 720f Proportional determinate errors, 61, 61t Propylamine, acid dissociation constant for, 738t Protecting agent, 420 Protein, total serum, UV/visible spectroscopy analysis of, 397t Protein-bound iodine, UV/visible spectroscopy analysis of, 397t Protocol, 37, 48 Protocol for a specific purpose (PSP), 707 Protons, conservation of, 22–23 Pseudo-order reactions, and method of initial rates, 753 PSP See Protocol for a specific purpose (PSP) Purge-and-trap system, 214, 214f Pyridine, acid dissociation constant for, 738t Q Q-test See Dixon Q-test Qualitative analysis, Quality assessment, 708–712 external methods of, 711–712 internal methods of, 708–711 analysis of blanks in, 710 analysis of standards in, 710 and spike recoveries, 710–711 Quality assessment limits, for waters and wastewater, 708, 709t Quality assurance, 48, 705–721 components of, 705–708, 706f evaluation of, 712–721 prescriptive approach to, 712–714, 713f performance-based approach to, 714–721 using control chart for, 721 Quality control, 48, 706 Quantification, limit of, 96 Quantitative analysis, Quantitative transfer, 30 Quantum yield, 425 Quartering, coning and, 199, 199f Quench, 634 Quinine, in urine, determination of, 431–432 R Radiation electromagnetic See Electromagnetic radiation incident, 443 stray, 387–388 Radiationless deactivation, in fluorescence and phosphorescence spectroscopy, 424–427, 425f Radioactive analytes direct analysis of, 644–645 isotopes half-life of, 643 rate of decay for, 643 particles, 642 Radiochemical methods, 642–649 characterization applications, 647–648 direct analysis, 644–645 evaluation of, 648–649 instrumentation in, 643–644 isotope dilution, 646–647 neutron activation analysis, 645–646 quantitative analysis using, 644–647 theory and practice in, 643 Raman spectroscopy, 373t Random number table, 728t Random sampling, 183–184 Range, 56 Rate of chemical reactions, 624, 750–751 and direct-computation rate methods, 629–630 and initial rate method, 753 maximum, for enzyme-catalyzed reactions, 638 Rate constant, 624 Rate law, 624–635, 750–751 Rayleigh scattering, 441, 441f Reaction(s) acid-base See Acid-base reactions complexation See Complexation reactions enzyme-catalyzed, 636–638, 637f equilibrium constants for, 139–148 first-order, 751–752, 753f ladder diagrams of, 150–155 noncatalytic, 638 nonenzyme-catalyzed, 637–638 oxidation-reduction, 23, 145–148, 748–749 precipitation, 22, 139–140, 504, 504t pseudo-order, 753 rate constant for, 624 rate law for, 624–625 rate of, 624, 750–751 reversible, 136 second-order, 752–753, 753f Reaction unit(s), 21 in acid-base reactions, 22 in complexation reaction, 23 for oxidizing agent, 23 in precipitation reaction, 22 in redox reactions, 23 for reducing agent, 23 Reagent(s) primary, 106–107 recommended for preparing primary standards, 729–730 secondary, 107 used as standards, 106–108 Reagent blank corrections, 128–129, 128t–129t Reagent grade, 107, 107f, 180 Recovery, 202 793 Recrystallization, 205t, 210 Redox electrodes, 475 Redox indicators, 338–339, 339f, 339t Redox reactions balancing of, 748–749 ladder diagrams for, 155, 155f–156f reaction units in, 23 Redox titration(s), 331–350 analyte’s oxidation state in, adjustment of, 341–342 end point in finding potentiometrically, 339, 339f selection and evaluation of, 337–339 with visual indicator, 338–339, 339f, 339t equivalence points in, 337–338, 338f evaluation of, 350 in inorganic analysis, 344–345 in organic analysis, 346–347 quantitative applications involving, 341–350 calculation of, 347–350 representative method in, 340 titrants in, selecting and standardizing of, 342–344, 343t Redox titration curves, 332–336, 350f calculation of, 333–334 sketching of, 335, 335f–336f, 335t Reducing agent, 146 auxiliary, 341 reaction units for, 23 Reduction, 146 Reductor column, 341, 341f selected reductions in, 341, 342t Reference electrodes, 462–463, 471–473, 473f–474f Refractor index detector, for high-performance liquid chromatography, 585 Regression curvilinear, 127 equation, 122–124, 124f linear See Linear regression standard deviation about the, 121 Reilly, C N., Relative supersaturation (RSS), 241 Relative uncertainty in concentration, in UV/visible and infrared spectroscopy, 410–411, 410t, 411f Relaxation, 423 Releasing agent, 420 Repeatability, 62 Reproducibility, 62 Residual current, 513 correcting in voltammetry, 521 Residual error, 118 in linear regression, 118, 119f Resolution, 376 in capillary electrophoresis, 601 in chromatography, 549–550, 549f–550f optimization of, capacity factor and, 556–558, 557f–558f Resorcinol, acid dissociation constant for, 738t Response, 667 1400-Indx 9/27/99 2:17 PM Page 794 794 Index Response surfaces, Color Plate 8, 667–668, 667f–668f central composite designs for, 682–683, 683f empirical models for, 675–676 factorial designs for, 676–682, 676f, 681f–682f mathematical models for, 674–683 searching algorithms for, 668–674, 668f theoretical models for, 675 Results characterization of, in analytical data, 54–57 distribution of, 70–82 Retention time, 548, 548f Retention volume, 548 Reverse-phase chromatography, 580 Reverse-phase separation, 582 solving triangle for, 582, 582f Reversibility, electrochemical, 527–528 Reversible reactions, 136 Riffle, 198, 198f Rinsing, precipitate, in precipitation gravimetry, 244–245 Robust, 42 RSS See Relative supersaturation (RSS) Rugged, 42 Ruggedness testing, and standard method, 684–687, 684t Ruthenium, standard reduction potentials for, 745t S Safe Drinking Water Act, 36 Salicylic acid, 323t acid dissociation constant for, 738t Salt bridge, 466 Salt substitute, sodium in, 439–440 Sample(s), 71, 71t composite, 185 composition of, and target populations, 182–185 confidence intervals for, 80–81, 81t duplicate, 708 grab, 185, 197, 197f gross, 193 injection of, in capillary electrophoresis, 602 introduction of in gas chromatography, 567–568 in high-performance liquid chromatography, 584, 584f laboratory, 199 matrix, effect on normal calibration curve, 110, 110f means, comparison of, 88–93 multicomponent, 386 Beer’s law and, 386 number of, 191–192 obtaining of, 179–224 preparation of, 179–224 in atomic absorption spectroscopy, 418 in atomic emission spectroscopy, 437 in spectroscopy based on scattering, 443–444 primary See Gross sample probability distributions for, 77–80 and central limit theorem, 77–79, 78t, 79f in situ, 185 size of, 187–190 solid See Solid samples solution, 193–195, 195t standard, 683 blind analysis of, 683 types of, 185–186 volatile, 567–568 Sample thief, 198, 198f Sampling, 47 convenience, 185 headspace, 567 importance of, 180–182 judgmental, 184 overall variance attributable to method and, 180, 180f procedure in, 47 random, 183–184 stratified, 185 systematic, 184, 184f systematic-judgmental, 184–185, 186f Sampling error, 58 Sampling plan design of, 182–193 implementation of, 193–201 overall variance in, minimization of, 192–193 Sanders, 465 Saturated calomel electrodes, 472, 473f Scattering elastic, 441 large-particle, 441, 441f origin of, 441 Rayleigh, 441, 441f small-particle See Rayleigh scattering spectroscopy based on, 441–445 Scientific notation, 12 Scintillation counter, 643–644 SCOT See Support-coated open tubular columns (SCOT) Screened indicators, 289t Searching algorithms, for response surfaces, 668–674, 668f effectiveness and efficiency, 668–669 Second, 12t Secondary reagents, 107 Second derivative titration curve, 291t, 292, 292f Second-order reactions, 752–753, 753f Sediments, sampling of, 197, 197f Selectivity, of membrane, 476–477, 477f Selectivity coefficient, 40, 477, 477f Selenium, standard reduction potentials for, 745t Self-absorption, 428 Separation(s) See also Extraction(s) analytical, 544–547 chromatographic, 215 optimizing of, 556–563 phases in, 546 modules in flow injection analysis, 653, 654f versus preconcentration, 223–224 techniques See Separation techniques, classification of Separation efficiency, general theory of, 202–205 Separation factor, 203 Separation techniques, classification of, 205–215, 205t change of state, 209–211 complexation reactions, 207–209 mass or density, 206–207 partitioning between phases, 211–215, 212f, 213t size, 205–206 Separatory funnel, Color Plate 3, 212, 212f Serine, acid dissociation constant for, 738t Serum, fluoxetine in, 588–589 Serum barbiturates, UV/visible spectroscopy analysis of, 397t Serum cholesterol, UV/visible spectroscopy analysis of, 397t Serum protein, total, 397t SFC See Superfluid chromatography (SFC) SHE See Standard hydrogen electrode (SHE) Shorthand notation, for potentiometric electrochemical cells, 467–468 Signal(s), 37 calibration of, 105–106 photons as, 372–374, 373f, 373t in total analysis techniques, 38 using mass as, 233–234 volume as, 274–275 Signal averaging, 391, 391f Signal processors, 380 Signal-to-noise ratio, 379 Sign conventions, in voltammetry, 510–513 Significance testing, 82–83, 82f construction of, 83 errors in, 84–85 one-tailed and two-tailed, 84, 84f Significant figures, 13–15 Silica, 213t Silicon, standard reduction potentials for, 745t Silver and argentometric titrations, 355, 355t standard reduction potentials for, 745t Silver chloride, solubility curve of, 236, 236f Silver/silver chloride electrode, 473, 474f Simplex optimization, 671–674, 671f, 673t, 674f–675f Simulated Rainwater (SRM), 62f Single-arm mechanical balance, 25, 26f Single-column ion chromatography, 593 Single-operator characteristics, 683 Single-point external standardization, 117 Single-point standardization, 108, 108f constant determinate error and, 118, 118t versus multiple-point standardizations, 108–109 Single-sided normal distribution, 725t–726t Singlet excited state, 423, 424f SI units, 12, 12t–13t 1400-Indx 9/27/99 2:17 PM Page 795 Index Size-exclusion chromatography, 205t, 206, 593–596, 595f–596f Slit orientation, and sensitivity, in fluorescence spectroscopy, 433, 433f Slit width, selection of in atomic absorption spectroscopy, 415–418 in atomic emission spectroscopy, 437 Slope, estimated, determination by linear regression, 119 Slope-ratio method, 407 Slow injection analysis, 649–658 Small-particle scattering See Rayleigh scattering SMDE See Static mercury drop electrode (SMDE) Smith-Hieftje background correction, 419 Sodium absorption spectrum for, 384, 384f in salt substitute, 439–440 standard reduction potentials for, 745t valence energy diagram of, 383, 383f Sodium hydroxide, as indicator for acid-base titrations, 278 Sodium tetraphenylborate, 249t Solid electrodes, in voltammetry, 510, 510f Solid-phase extraction, 212–213, 212f, 213t adsorbents for, 212–213, 213t Solid-phase microextraction (SPME), 213, 567 Solid samples, 196–201 bringing into solution, 200–201, 200f, 200t collection of, 197–198, 197f digestion of, 200–201, 200f, 200t preparation of, 198 preservation of, 198 reducing particle size in, 199–200 Solid-state ion-selective electrodes, 479–482, 481t Solubility, effect of complexation on, 165–167 Solubility product, 140, 731t–732t Solute, total velocity of, in capillary electrophoresis, 599–600 Solution(s) buffer See Buffer solutions preparation of, 30–32 stock, 30–31 Solution samples, 193–195 collection of, 193–194 preparation of, 195 preservation of, 194–195, 195t Solvent dissociation constant of, 295 nonaqueous, acid-base titrations in, 294f, 295–296, 296f Solvent triangle, 582, 582f SOP See Standard operations procedure (SOP) Soxhlet extractor, 214, 214f Spectral interference in atomic absorption spectroscopy, 418–419 in atomic emission spectroscopy, 437–438, 438f Spectral searching, 403, 404f Spectrofluorometer, 434 Spectrometer(s) atomic emission, 436, 436f Fourier transform infrared, 378, 381, 381f, 393, 570–571 infrared, 393 mass, 570–571, 585–586 Spectrometry, and concentration technique, 38 Spectrophotometers, 389, 389f–390f atomic absorption versus molecular absorption, 412 calibration of, 106 Fourier transform infrared, 570–571 and gas chromatography, 570–571 mass, 570–571 Spectrophotometric titration curves, for complexation titration, 324, 324f, 331, 331f Spectroscopic detectors, for high-performance liquid chromatography, 584–585 Spectroscopy, 368–445 atomic absorption See Atomic absorption spectroscopy atomic emission See Atomic emission spectroscopy atomic fluorescence, 373t based on emission, 423 based on scattering, 441–445 electron spin resonance, 373t fluorescence See Fluorescence spectroscopy graphite furnace atomic absorption, 36, 37f, 48, 49f infrared See Infrared spectroscopy instrumentation in basic components of, 374–380 detectors, 379–380 signal processors, 380 sources of energy for, 375, 375t transducers, 379–380, 380t wavelength selection, 376–379, 376f microwave, 373t molecular absorption, 388–394 Mossbauer, 373t overview of, 369–374 phosphorescence See Phosphorescence spectroscopy photoluminescence See Photoluminescence spectroscopy Raman, 373t signals in, measuring photons as, 372–374 types of, 372–374 involving exchanges of energy, 372, 373t not involving exchanges of energy, 374, 374t ultraviolet/visible See Ultraviolet/visible spectroscopy x-ray absorption, 373t Spectrum emission, 374, 427, 427f excitation, 427 mass, 571 ultraviolet/visible, Color Plate 6, 382–384, 383f Spike recovery, 710–711 795 Split injection, 568 Splitless injection, 568 SPME See Solid-phase microextraction (SPME) Spread, measures of, 55–57 Squalane, 566t SRM See Simulated Rainwater (SRM) Stacking, in capillary electrophoresis, 603, 603f Standard(s) analysis of, in quality assessment, 710 external, 109–110 in atomic emission spectroscopy, 438 in potentiometry, 486–487 internal, 115–117 in atomic emission spectroscopy, 438 primary, recommended reagents for, 729–730 proficiency, 711 reagents used as, 106–108 Standard additions, Color Plate 2, 110–115 Standard buffers, primary, pH of, 492t Standard deviation, 56–57 about the regression, 121 Standard hydrogen electrode (SHE), 471–472, 472f Standardization, 47 external multiple-point, 117, 117t single-point, 117 multiple-point, 109 versus single-point, 108–109 of procedure, 47 single-point, 108–109, 108f, 118, 118t of titrants, 298–300, 299t in complexation titrations, 327 in redox titrations, 342–344, 343t Standard method, 106 in atomic absorption spectroscopy, 420–421 in atomic emission spectroscopy, 438–440 and blind analysis of standard samples, 683 development of, 666–698 and equivalency testing, 687 in fluorescence and phosphorescence spectroscopy, 431–432 optimizing experimental procedure with, 667–683 response surfaces and, 667–674, 667f–668f in phosphorescence spectroscopy, 431–432 in photoluminescence spectroscopy, 431–432 and ruggedness testing, 684–687, 684t single-operator characteristics of, 683 two-sample collaborative test and, 688–693, 689f, 691f validating method as, 687–698 verification of, 683–687 Standard operations procedure (SOP), 707 Standard reduction potentials, 743t–746t Standard reference material, 61 Standard sample, 683 Standard solution, 108 Standard-state conditions, 137 Standard-state potential, determining by voltammetry, 514–515, 515f 1400-Indx 9/27/99 2:17 PM Page 796 796 Index Static mercury drop electrode (SMDE), 509, 509f Stationary phase(s), 546 bonded, 580 in gas chromatography, 565–567, 566f, 567f bleed and, 566 in high-performance liquid chromatography, 579–580 Statistical analysis, of data, 82–85 Steady-state approximation, 636 Stepwise formation constant, 144 Stock solution, preparation of, 30–32 Stoichiometry calculations in, 20–25 using conservation principles in, 23–25 of metal-ligand complex, 403–407, 406f Stopped flow analyzer, 634, 635f Straight-line calibration curves, linear regression of, 118, 119f Stratified sampling, 185 Stray radiation, 387–388 Stripping voltammetry, 516–519, 518f, 519t Strontium, standard reduction potentials for, 745t Styrene, 213t Sublimation, 205t, 209 Subrange precision control charts, 718, 719f Substrate, 636 Succinic acid acid dissociation constant for, 738t titration curve for, 288, 288f Sulfate solubility products for, 732t in water, turbidimetric determination of, 445 Sulfide, solubility products for, 732t Sulfur, standard reduction potentials for, 745t Sulfuric acid, acid dissociation constant for, 738t Sulfurous acid, acid dissociation constant for, 738t Supercritical fluids continuous extraction of, 215 critical point properties of, 596, 597t equipment for studying, Color Plate phase diagram of, 596, 596f properties of, 596, 596t Superfluid chromatography (SFC), 596–597 mobile phases for, 596, 597t Supernatant, 244, 244f Support-coated open tubular columns (SCOT), 565 Surface adsorbates, 239, 239f Surfactants, in waters and wastewater, 395t Syringes, types of, 28, 28f Systematic-judgmental sampling, 184–185, 186f Systematic sampling, 184, 184f Système International d’Unités See SI units T Tailing, in column chromatography, 555, 555f Tare, 26 Target populations, sample composition and, 182–185 TCD See Thermal conductivity detector (TCD) Technique, 36 classification of, 37–38 Temperature finding end point by, 293–295, 294f programming, 558 scales for, 13t SI and non-SI units for, 13t SI unit for, 12t Tetraethylthiuram disulfide, 21, 24 Thallium, standard reduction potentials for, 745t Theorem central limit, 77–79, 78t, 79f Nyquist, 184 Theoretical models, for response surfaces, 675 Theoretical plate, 553 net height of, 560–563, 562f and resolution in chromatography, 559–560, 560t Thermal conductivity detector (TCD), 569, 569f Thermal energy, sources of, in spectroscopy, 375 Thermal excitation, spectroscopies involving, 373t Thermal ionization mass spectrometry, 7–8 Thermal transducers, 379–380, 380t Thermodynamic equilibrium constant, activity and, 172–173 Thermodynamics, and equilibrium chemistry, 136–138 Thermogram, 256, 256f Thermogravimetry, 255–257, 256f Thermometric titration curve, 293–295, 294f Thiocyanate, solubility products for, 732t Thiosulfate, 344 Thiosulfuric acid, acid dissociation constant for, 738t Threonine, acid dissociation constant for, 738t Thymol blue, 289t Time, SI unit for, 12t TIMS See Thermal ionization mass spectrometry Tin, standard reduction potentials for, 746t TISAB See Total ionic strength adjustment buffer (TISAB) Titanium, standard reduction potentials for, 746t Titrant, 274 selection and standardization of, 298–300, 299t in complexation titrations, 327 in redox titrations, 342–344, 343t Titration(s) acid-base See Acid-base titration(s) argentometric, 355 back, 275 complexation See Complexation titrations coulometric, 503–504, 503t, 505–506 diffusional microtitration, 312, 312f displacement, 275 end-point of, selection and evaluation of, 287–295 instrumentation for, 278, 279f potentiometric, 494 precipitation See Precipitation titration(s) redox See Redox titration(s) Titration curve(s), 275–276, 276f–277f acid-base, 279–287, 285f–286f of acids, 280–284, 281t, 283f, 283t, 288, 288f of bases, 280–284, 281t, 283f, 283t for complexation titrations, 324, 324f, 331, 331f of EDTA, 317–322, 319f, 320t, 321f–322f finding end point using, derivative method for, 291t, 292–293, 292f first derivative, 291, 291t, 292f precipitation, 350–353, 352f, 352t, 353f, 357f redox, 332–336, 335f–336f, 335t, 350f second derivative, 291t, 292, 292f thermometric, 293–295, 294f Titration error, 274 Titrimetry, 273–357 overview of, 274–278 as total analysis technique, 38 Tolerance, 58 Toothpaste, fluoride in, 489–490 Total analysis techniques, 38 signals in, 38 Total ionic strength adjustment buffer (TISAB), 487 Total mobility, in capillary electrophoresis, 599–600 Total serum protein, UV/visible spectroscopy analysis of, 397t Total velocity, of solute, in capillary electrophoresis, 599–600 Total Youden blank, 129 Trace metals Contract Laboratory Program protocols for, 48, 49f in environmental samples, voltammetry and, 524–525, 525t Tracer, 646 Transducers photon, 379, 380t thermal, 379–380, 380t Transitions See Electronic transitions Transmittance, 384 in absorption spectroscopy, 384–385, 384f Transport system, in flow injection analysis, 652 Trichloroacetic acid, acid dissociation constant for, 738t Triethanolamine acid, acid dissociation constant for, 738t Triethylamine, acid dissociation constant for, 738t Trihalomethanes, in drinking water, 576–577 Trip blank, 710 1400-Indx 9/27/99 2:17 PM Page 797 Index Triplet excited state, 423, 424f Triprotic acid, pH of, 165 Triprotic base, pH of, 165 Tswett, Mikhail, 546 t-test, 85–86, 726t paired, 92–93 Tungsten, standard reduction potentials for, 746t Turbidimeter, 442, 442f Turbidimetry, 441–445 applications of, 444–445 determination of concentration by, 442–443 and determination of sulfate in water, 445 versus nephelometry, 442 precipitates used in, 443–444, 444t Turnover number, 638 Two-factor response surface, 669–671, 669f–671f Two-sample collaborative test, 688–693, 689f, 691f Two-tailed significance test, 84, 84f t-table for, 726 Type error, 84–85 Type error, 84–85 U Ultraviolet/visible radiation, versus infrared, absorption of, 381, 381f Ultraviolet/visible spectrophotometry, for highperformance liquid chromatography, 585, 585f Ultraviolet/visible spectroscopy, 373t, 388–412 accuracy in, 409 and analysis of waters and wastewater, 395, 395t, 398–399 for atoms, 383–384 cells used in, 391, 392f characterization applications involving, 403–409 clinical applications involving, 397, 397t determination of equilibrium constants in, 407–409 environmental applications involving, 395–396, 395t evaluation in, 409–412 forensic applications involving, 398 industrial applications involving, 397–398 instrumentation in, 388–394 designs of, 388–393 for molecules and ions, 382–383, 383f precision in, 409–411, 411f qualitative applications involving, 402–403 quantitative applications involving, 391, 392f developing method for single component, 398–399 for mixtures, 400–402 for single analyte, 400 and relative uncertainty in concentration, effect of indeterminate instrument errors on, 410–411, 410t, 411f scale of operation in, 409 selectivity in, 412 sensitivity in, 411 time, cost and equipment in, 412 visible spectrum, Color Plate Uncertainty See also Relative uncertainty in concentration, in UV/visible and infrared spectroscopy in addition or subtraction, 65–66 calculation of, usefulness of, 68–70 error and, 64 in linear regression, 120–122, 120f for mixed operations, 66 in multiplication or division, 66 for other mathematical functions, 67–68, 68t precision versus, 64, 64t propagation of, 64–70 Uncompetitive inhibition, of enzymes, 639, 640f Universal indicator, for pH, Color plate Unpaired data, 88–91 Unweighted linear regression, with errors in y, 119–124 Uranium, standard reduction potentials for, 746t Uric acid, UV/visible spectroscopy analysis of, 397t Urine creatinine in, 632–633 determination of quinine in, 431–432 V Validation, 47 of standard method, 687–698 Vanadium, standard reduction potentials for, 746t van Deemter equation, 561 Variable-time integral methods, 628–629 Variance, 57 analysis of, 693–697 and F-test, 88 measurement of, 57 overall, 192–193 of populations, 79 Velocity electroosmotic flow, 599 electrophoretic, 598 total, 599–600 Verification, of standard method, 683–687 Vibrational relaxation, 424, 425f Visual indicators See Indicator(s) Vitamin(s), natural fluorescence of, 430t Vitamin B complex, 607–608 VOCs See Volatile organic compounds (VOCs) Void time, 549, 549f Void volume, 549 Volatile organic compounds (VOCs), extraction of, 214 Volatile sample, preparation of, in gas chromatography, 567–568 Volatilization, 205t 797 Volatilization gravimetry, 234, 255–262 equipment used in, 257 evaluation of, 262 and inorganic analysis, 259 in organic analysis, 259–260 quantitative applications involving, 259–262 calculations in, 260–262 representative method of, 257–258 theory and practice in, 255–258 Volhard method, 354, 355t Volt, 13t Voltammetric electrochemical cell, 510, 511f Voltammetry, 508–532 accuracy in, 531 characterization applications of, 527–530 and concentration technique, 38 correcting residual current in, 521 current in, 510–513 evaluation of, 531 hydrodynamic, 513, 516–519 precision in, 531 quantitative and qualitative aspects of, 514–515 quantitative applications using, 520–527 for analysis of single components, 521–523 and clinical samples, 525, 526t and environmental samples, 524–525, 525t and miscellaneous samples, 525–527 for multicomponent analysis, 523–524, 523f selecting technique for, 520–521 scale of operation in, 531 selectivity in, 531 sensitivity in, 531 sign conventions in, 510–513 solid electrodes in, 510, 510f stripping, 516–519, 518f, 519t techniques in, 515–520 time, cost and equipment in, 531 voltammetric measurements, 509–510 Voltammogram, 508 effect of complexation on, 528–530, 528f shape of, 513–514, 513f Volume breakthrough, 196 end point for phosphate species, 308t and sources of alkalinity, 301, 302t equipment for measuring of, 26–29, 27f–28f retention, 548 as a signal, 274–275 SI unit for, 12t void, 549 weight-to-volume percent, 18 Volume percent, 18 Volumetric flask, 26, 27f measurement errors for, 59t, 60 1400-Indx 9/27/99 2:17 PM Page 798 798 Index W Walden reductor, 341 selected reductions using, 341, 342t Wall-coated open tubular columns (WCOT), 565 Walsh, A., 412 Waters and wastewater See also Drinking water dissociation of, 142 constant for, 142–143 preservation methods and maximum holding times for, 195, 195t quality assessment limits for, 708, 709t sulfate in, 445 UV/visible spectroscopy of, 395, 395t, 398–399 Watt, 13t Wavelength, 370 nominal, 376 selection of, 376–379, 376f in atomic absorption spectroscopy, 415–418, 418t in atomic emission spectroscopy, 437 in spectroscopy, 376–379, 376f using filters, 376 using monochromators, 376–378, 378f Wavenumber, 370–371 Wave properties, of electromagnetic radiation, 369–371, 369f WCOT See Wall-coated open tubular columns (WCOT) Weight equivalent, 17, 309–310 formula, 17 Weighted linear regression with errors in both x and y, 127 with errors in y, 124–127, 126f Weight percent, 18 Weight-to-volume percent, 18 Work, SI and non-SI units for, 13t X X-ray absorption spectroscopy, 373t X-ray fluorescence, 373t Y y-intercept, determination of, by linear regression, 119 Z Zeeman effect background correction, 419 Zeta potential, 599 Zinc standard reduction potentials for, 746t in waters and wastewater, 395t 1400-Indx 9/27/99 2:17 PM Page 799 1400-Indx 9/27/99 2:17 PM Page 800 ... analytical chemistry and the unique perspectives that analytical chemists bring to the study of chemistry 1400-CH01 9/9/99 2:20 PM Page 2 Modern Analytical Chemistry 1A What Is Analytical Chemistry? “Analytical... A History of Analytical Chemistry The Division of Analytical Chemistry of the American Chemical Society: Washington, D.C., 1972 McLafferty, F W “Analytical Chemistry: Historic and Modern, ” Acc... “Analytical chemistry is what analytical chemists do.”* We begin this section with a deceptively simple question What is analytical chemistry? Like all fields of chemistry, analytical chemistry