detectors in gas chromatography

Journal of Chromatography Library - Volume DETECTORS IN GAS CHROMATOGRAPHY JOURNAL OF CHROMATOGRAPHY LIBRARY Volume Chromatography of Antibiotics by G H Wagman and M J Weinstein Volume Extraction Chromatography edited by T Braun and G Ghersini Volume Liquid Column Chromatography A Survey of Modern Techniques and Applications edited by Z Deyl, K Macek and J Janak Volume Detectors in Gas Chromatography by J SevCik Journal of Chromatography Library - Volume DETECTORS IN GAS CHROMATOGRAPHY JIkf SEVcfK Department of Analytical Ciieunistrj., Ciiarles University, Prague ELSEVIER SCIENTIFIC PUBLISHING COMPANY AMSTERDAM - OXFORD - NEW YORK 1976 Distribution of this book is being handled by the following team of publishers for the U.S.A and Canada AMERICAN ELSEVIER PUBLISHING COMPANY, INC 52 Vanderbilt Avenue New York New York 10017 for the East European Countries, China, Northern Korea, Cuba, Vietnam and Mongolia SNTL, PUBLISHERS OF TECHNICAL LITERATURE Prague for all remaining areas ELSEVIER SCIENTIFIC PUBLISHING COMPANY 335 Jan van Galenstraat P Box 211, Amsterdam, The Netherlands Library of Congress Cataioging in Publication Data “ 4’ (’ Sevcik, Jiri Detectors i n gas chromatography (Journal of c h r m t c g r a p h y l i b r a r y ; v ) Includes b i b l i o g r a p h i c a l referenees and index Gas chranatography I T i t l e 11 Series C45548 544’ 926 75-30850 ISBN 0-444-9985 -8 Q JIRI SEVCfK 1975 Translation KAREL STULfK 1976 ALL RIGHTS RESERVED NO PART OF THIS PUBLICATION MAY BE REPRODUCED, STORED IN A RETRIEVAL SYSTEM, OR TRANSMITTED I N ANY FORM OR BY ANY MEANS, ELECTRONIC, MECHANICAL, PHOTOCOPYING, RECORDING OR OTHERWISE, WITHOUT PRIOR WRITTEN PERMISSION OF THE PUBLISHERS Elsevier Scientific Publishing Company, Jan van Galenstraat 335, Amsterdam PRINTED IN CZECHOSLOVAKIA CONTENTS List of symbols Preface 12 Introduction 15 1.1 Concentration distribution of the eluted substance at the column outlet 1.2 Detector signal 1.2.1 Detector response 1.3 Effect of the measuring device on signal changes 1.4 Sample injection 1.5 Parameters characterizing detectors 1.5.1 Sensitivity 1.5.2 Detector linearity 1.5.3 Linear dynamic range 1.5.4 Lowest detectable amount 1.5.5 Detector selectivity 1.6 Literature The Thermal Conductivity Detector (TCD) 2.1 Detection mechanism 2.2 TCD signal 2.2.1 TCD background current 2.2.2 TCD response 2.3 Effect of experimental parameters on the magnitude.and shape of the TCD signal 2.3.1 Carrier gas 2.3.2 Construction of the TCD 2.3.2.1 Sensor heating voltage 2.3.2.2 Sensor parameters 2.3.2.3 Cell geometric constant 2.3.2.4 Temperatures of the sensor and the cell walls 2.3.2.5 Time constant of the TCD 2.3.2.6 Measuring circuits 2.4 Applications of the TCD 2.5 Literature Ionization Detectors 3.1 Physical principles of the detection 3.1.1 The collision 3.1.2 Effect of the electric field intensity 17 22 23 24 28 30 31 32 33 34 36 37 39 39 42 43 43 46 46 47 49 49 51 52 52 55 56 57 59 59 60 62 3.2 Ionization energy sources 3.3 Reactions in the ionization detector 3.3.1 The slow-down mechanism 3.3.2 Recombination 3.3.3 Background current of the ionization detector 3.4 Literature 65 68 68 69 71 71 The Electron Capture Detector ( E C D ) 72 4.1 Detection mechanism 4.2 ECD signal 4.2.1 ECD background current 4.2.2 ECD response 4.2.2.1 Linearity and linear dynamic range 4.2.2.2 Sensitivity and selectivity of the ECD 4.3 Experimental conditions affecting the ECD signal 4.3.1 Carrier gas 4.3.2 Construction of the ECD 4.4 Applications of the ECD 4.5 Literature 72 74 74 76 77 77 79 79 80 82 85 The Flame Ionization Detector (FID) 87 5.1 Detection mechanism 5.2 FID signal 5.2.1 FID background current 5.2.2 FID response 5.2.2.1 Linear dynamic range and linearity of the FID 5.2.2.2 Sensitivity and selectivity of the FID 5.3 Experimental conditions affecting the magnitude and character of the FID signal 5.3.1 Gas flow-rate 5.3.2 Geometry of the FID 5.4 FID applications 5.5 Literature 87 91 92 92 94 95 95 95 97 101 102 The Thermionic Detector Using an Alkali Metal Salt (TIDAj 105 6.1 Detection mechanism 106 6.2 TlDA signal 109 6.2.1 TlDA background current 110 6.2.2 TIDA response 112 6.2.2.1 Linearity and linear dynamic range of the TlDA 115 6.2.2.2 Sensitivity and selectivity of the TIDA 116 6.3 Effect of the experimental conditions on the magnitude and character of the TIDA signal 117 117 6.3.1 Gas flow-rate 6.3.2 Detector geometry 118 6.4 TIDA applications 120 121 6.5 Literature The Photoionization Detector (PID) 123 7.1 Detection mechanism 123 7.2 PID signal 7.2.1 PID background current 7.2.2 PID response 7.3 Effect of the experimental conditions on the PID signal 7.3.1 Carrier gas 7.3.2 Geometric arrangement of the PID 7.3.2.1 Discharge compartment 7.3.2.2 Detection compartment 7.4 PID applications 7.5 Literature i25 i27 127 128 128 129 129 130 131 133 The Helium Detector (HeD) 8.1 Detection mechanism 8.2 HeD signal 8.2.1 HeD background current 8.2.2 HeD response 8.2.2.1 Linearity and linear dynamic range of the HeD 8.2.2.2 Sensitivity and selectivity of the HeD 8.3 Effect of experimental conditions on the HeD signal 8.3.1 Carrier gas 8.3.2 Construction of the helium and argon detectors 8.4 HeD applications 8.5 Literature The Flame Photometric Detector (FPD) 133 133 135 135 136 139 140 140 140 141 143 144 9.1 Detection mechanism 9.2 FPD signal 9.2.1 FPD background current 9.2.2 FPD response 9.2.2.1 Linearity and linear dynamic range of the FPD 9.2.2.2 Sensitivity and selectivity of the FPD 9.3 Effect of experimental conditions on the magnitude of the FPD signal 9.3.1 Composition of the gases and their flow-rates 9.3.2 Detector temperature 9.3.3 Construction 9.4 Use of the flame photometric detector 9.5 Literature 10 The Coulometric Detector ( C D ) 10.1 Detection mechanism 10.2 CD signal 10.2.1 CD background current 10.2.2 CD response 10.2.2.1 Linearity and linear dynamic range of the CD 10.2.2.2 Sensitivity and selectivity of the CD 10.3 Effect of experimental conditions on the magnitude of the CD signal 10.3.1 Gas flow-rate 145 149 151 152 153 155 155 155 156 157 159 162 165 165 169 170 170 171 171 172 172 145 10.3.2Construction of the detector 10.3.2.1 Bias 10.3.3 Temperature 10.4 Applications of the CD 10.5 Literature 11 The Electrolytic Conductance Detector ( E l C D ) 172 175 175 175 179 181 11.1 Detection mechanism 11.2 ElCD signal 11.2.1 ElCD background current 11.2.2 ElCD response 11.3 Construction of the ElCD 11.4 Applications of the ElCD 11.5 Literature 181 183 189 Index 185 185 186 187 188 LIST OF SYMBOLS A A A A a - atom - radioactive source activity - experimental constant - radiative transition probability - geometric constant a aa - probability ratio for two processes b B B - optical path length - atom bc bci C - analytical property of a - constant - background current - ionization background current - carrier gas C - instantaneous concentration co - initial concentration p i n CmaX c' C, Cy D e E EP E, F G H I I ic ic, i ic,,, minimum instantaneous concentration - maximum instantaneous concentration - instantaneous concentration in the effective volume of the detector - heat capacity at constant pressure - heat capacity at constant volume - diffusion coefficient - secondary electron, slow electron - voltage - excitation potential - excitation energy of the eluted substance - Faraday constant - mass - height equivalent to a theoretical plate - current - atom or molecule of impurity - ionization current - ionization current of alkali metal ~ - ionization ~ ~ current ~ of ~de-excited atomic states - ionization current due to electron capture - 178 TABLE 10.4 EXAMPLES O F THE APPLICATIONS OF THE COULOMETRIC DETECTOR Substance determined Lowest detectable amount Material analyzed Linear dynamic range Ref 2 2 HZS SO, CH3SH CH3SCH3 CH3SzCH3 Benzothiophenes, petrol dibenzothiophenes, distillation one-ring thiophenes fractions (CH,),SO 9x SO2 1.5 X lo-', 0.1 P d l SO2 at mosphere nitrogen cs2 Su1phur:containing substances Mercaptans, hydrocarbons sulphides, disulphides Sulphur 2-Chlorobenzoic acid Chlorobenzene gaseous mixtures CI2 atmosphere in Halogenated hydrocarbons submarines, bathyscaphes and satellites Chlorinated substances CH31, C,H,I CHBr, CCI, Chlorpicrin Trichloroethylene Pyridine, pyrrole, indole N-containing substances NO, NH, NO2 g/sec mole/sec 29 37 38 36 24,41 41 39 23 40 37 38 45 14 0.03 pg/l 10-6:< 2~ - % 10 ng - l ~g equiv/sec g/sec 0.01 mg/m3 10 ppb X lo-', atmosphere mole/sec 13 31 31 31 ppb PPb 300 ppb 3000 ppb 600 ppb 30 hydrocarbons nitrogen gaseous mixtures - 23 - l ~g equiv./sec 10-6x 24,40 0.1 mg/m3 34,38 179 Table 10.4 (continued) Substance determined Acids, aldehydes, ketones H,, , CH, He, Ar, Ne, N,, NO,, CO2 PH3 Pesticides Amino acids, carboxylic acids, phenols, carbohydrates Material analyzed Lowest detectable amount Linear dynamic range Ref 26 5x 10-~m1 20 oxygen food, air, water liquid chromatography ng pg level x lo-'' mole 12 43 acids, carboxylic acids, phenols and sacharides, the column is packed with an ion to x lo-'' mole However, exchanger and the detection limits vary from x with this instrument it is necessary to vary the composition of the reaction electrolyte with changes in the type of substance 10.5 LITERATURE I Aavik H E., Kabun A V., Kallasorg R., Revel'skii LA.: Ref Zh Khim 1972, 12 N 421 A d a m D F., Jensen G A,, Steadnian J P., Koppe R K., Robertson T J.: Anal Chem 38, 1094 (1966) Bailey P L., Bishop E.: Analysr 97, 31 (1972) Bechtold E.: Z Anal Cheni 221, 262 (1966) Berek B., Westlake W E., Gunther F A,: J Agric Food Chem 18, 143 (1970) Burchfield H P., Wheeler R J.: J Assoc Off Anal Chetn 49, 651 (1966) Burton G., Littlewood A B., Wiseman W A,: Gas Chromatography 1966, Butterworths, London 1966 Christian J D.: Anal Chetn 45, 698 (1973) Clegg J B.: J Chromatogr 52, 367 (1970) 10 Coulson D M., Cavanagh L A,: Anal Cheni 32, 1245 (1960) 11 Coulson D M.: J Gus Chrojnarogr 4, 1966, 285 12 Coulson D M.: Amer Lab 1969, 22 13 Cremer E., Bechtold E.: Swiss Pat 447,665 (March 29, 1968) 14 Cremer E., Bechtold E.: Swiss Pat 450,013 (Apr 30, 1968) 15 Dohrmann Instruments Company, San Carlos, Calif., Preliminary operation instructions for Dohrmann microcoulometric titrating system 16 Farzane N G., Ilyasov L V., Akhmerov A S.: Zlz Fiz Khim 44, 1363 (1970) 17 Fleet B., Risby T H.: Tulanru 16, 839 (1969) 18 Hersch P.: 2nstr Practice 11, 817, 937 (1957) 19 Hersch P.: Lect Gas Chromatogr 1966, 1967, 149 20 Ikels K G., Neville J R.: J Gas Chromatogr 6, 222 (1968) 21 Kissinger P T.,Refshauge C., Dreiling R., Adams R N.: Anal Lett 6, 465 (1973) 22 Kobayashi H., Wagner C.: J Chem Phys 26, 1609 (1957) 23 Krichmar S I., Stepanenko V E.: Zh Anal Khim 24, 1874 (1969) 24 Krichmar S I., Stepanenko V E., Galan T M.: Zh Anal Khim 26, 1340 (1971) 25 Lebenhart P., Sevtik J.: Coll Czech Chem Commun - in press 26 Liberti A.: Anal Chim Acta 17, 247 (1957) 21 Littlewood A B., Wiseman W A.: J Gas Chromatogr 5, 334 (1967) 28 MacDonald A,, Duke P D.: J Chromatogr 83, 331 (1973) 29 Martin R L., Grant J A.: Anal Chem 37, 644 (1965) 30 Martin R L.: Anal Chem 38, 1209 (1966) 31 McFee D R., Bechtold R R.: Amer 2nd Hyg Ass J 32, 766 (1971) 32 Mizany A.: J Chromatogr Sci 8, 151 (1970) 33 Phillips T R., Johnson E G., Woodward H.: Anal Chem 36,450 (1964) 34 Rostenbach R E., Kling R G.: J Air Pollut Contr Ass 12, 459 (1962) 35 Saltzmann B E.: Anal Chem 26, 1949 (1954) 36 Scaringelli F P., Rehme K H.: Anal Chem 41, 707 (1969) 37 SevEik J.: Chromatographia 4, 102 (1971) 38 SevEik J., Lebenhart P.: Enuiron Sci Technol - in press 39 Shibazaki Y , Tamura F.:Chem Abstr 74, 150 673p (1971) 40 Stepanenko V E., Krichmar S I.: Zh Anal Khim 26, 147 (1971) 41 Stepanenko V E., Krichmar S I.: Zuuod Lab 38, 1200 (1972) 42 Takata Y , Arikawa Y : Bunseki Kagaku 22, 312 (1973) 43 Takata Y , Muto G.: Anal Chem 45, 1864 (1973) 44 Wagner C.: J Chem Phys 21, 1819 (1953) 45 Williams F W., Umstead M E., Johnson J E.: Chem Abstr 72, 93 107q (1970) 46 Zeedijk H.; Chem Tech (Amsterdam) 23, 721 (1968) 47 Zhantalai B P.: USSR Pat 199 493 (Jul 13, 1967) 11 The Electrolytic Conductance Detector (ElCD) 11.1 DETECTION MECHANISM The use of the electrolytic conductance detector is based on the measurement of variations in the low-frequency conductance of electrolytes The electrolytes are formed by the chemical reactions with water of the products of the combustion of the eluted substances It follows from the principle of this detector that only those substances will be detected whose solutions behave as electrolytes, i.e., contain ionic forms of the eluted substances As most organic compounds are non-electrolytes, except for organic acids and bases which form weak electrolytes in water and give rise to a very low conductance, a combustion tube is placed at the outlet of the separating column Oxides or hydrides are formed on combustion and react with water to form dissociated acids or bases The principle of the electrolytic conductance detector was first utilized in 1955 [151 for the direct conductimetric determination of acids The combustion process was introduced by Piringer et al [lo, 111 in 1962 and was further developed by Coulson [2, 31 for the determination of halogens, sulphur and nitrogen in organic molecules Combustion is carried out under either oxidizing or reducing conditions and the detection mechanism can be described by the following reaction scheme: Combustion: S(CI, N)ORG + 0, S(CI, N)ORG + H2 -+ S0,(C12, NO,) + CO, + H (11.1) -+ H2S(HCI,NH,) + CH, + H,O (11.2) In solution SO, + 3H20 -+ SO, + 3H20 -+ N,O, CO, + H,O + 3H20 -+ -+ + SO:2 H + + SO:2 H + + 2NO; 2H30+ + C0;2H30+ (11.3) (11.4) (11.5) (1 1.6) 182 H30+ + S2+ CI- (11.8) OH- $ NHf (11.9) H2S + 3H20 -t 2H30+ HCI + H20 -+ NH, + H20 -t (11.7) From these equations, it can be seen that the change in the conductance is proportional to the concentrations of H + and OH- ions The concentrations of these ions in solution are proportional to the concentrations of the combustion products and hence to the concentration of the eluted substance The dissociation constant appears as a proportionality constant in this relationship (see Table 11.1) TABLE 1 THE DISSOCIATION CONSTANTS OF SOME ACIDS A N D OF AMMONIA Acid, base H2S03 H2S04 HNO2 H2C03 H2S HCI NH,OH Dissociated form HSO, so: HSO, so;- NO; HCO; co: HS S2 - c1- NH; PK,, P K ~ 1.54 X lo-' 1.02 x Completely 1.20 x 10-2 4.6 x 10-4 4.3 x lo-' 5.61 X l o - " 9.1 X l o - * 1.1 x 10-12 Completely 1.97 x - , 1.81 6.91 Temperature ("C) 18 25 1.92 3.37 6.37 10.25 7.04 11.96 4.75 12.5 25 18 25 The reactions of the combustion products resemble one another and therefore interferences may occur during measurement of the electrolytic conductance A column containing silver nitrate is therefore placed before the gaseous and liquid phase mixer in order to remove hydrogen chloride when sulphur is measured or sulphur oxides using calcium oxide when chlorine alone is to be monitored When a reducing combustion atmosphere is employed, the acidic products are trapped in an Sr(OH), scrubber and the measured variations correspond to basic NH, Interference from C in the detector mechanism is very small It is usually stated in the literature that its dissociation rate is low The solubilities of the combustion products are given in Table 11.2 and show that, although the solubilities of COz or HzS are 25 times and 85 times that of SOz, respectively, their interference is nonethe- 183 less very small Hence it is evident that the extent of dissociation rather then the solubility is decisive for determining the interference from individual hetero-atoms TABLE 11.2 SOLUBILITY OF SOME GASES IN WATER AT 20 "C Litres of gas/litre of water Gas co2 0.859 0.0394 2.526 0.046 89.9* 82.3* SO2 HZS NO NH3 HCI * grams of 11.2 gas in 100 g of water ElCD SIGNAL The signal of the electrolytic conductance detector corresponds to changes in the conductance of the solution due to the varying concentration of the eluted substance If the resistance of the solution is R , then the conductance is proportional to the sum of the products of the concentrations, ci, charges, zi, and ionic mobilities ,Ii, of the ions present in the solution: - _ I & z , ~ , R (11.10) Q i where Q is the vessel constant (cm) The concentrations of the ionic forms of weak electrolytes depend on the magnitude of the dissociation constant and on the overall concentration, c, of the hetero-atom eluted from the column The dependence is S-shaped and can be described by the equation [H'] = J[lO-'" j- ( c a)'] (11.11) where a is the degree of dissociation, for which u = where x = -x K,,/c + x2 + 4x (11.12) 184 Hence the signal, e.g., for sulphur, will be given by the expression sEJCD = - ,/[10-14 + ( c q](I+,+ + (1 I 13) Q The ionic conductance of anions and cations are similar except for H" and OHions, whose conductances are several times higher (see Table 11.3) The detector TABLE 11.3 IONIC CONDUCTANCE VALUES AT 25 "C Ion i.j H+ 50 Ton $so:- 79 71 NO; c1OH- N H ~ 192 76 75 %:I I 2 -log c FIG 1 The relationship between the logarithm of the dissociation constant and the overall concentration of an acid or a base The shaded area indicates the region of complete dissociation of the acid or base - loge FIG 11.2 The equivalent conductances of several electrolytes in water [15]; - SO,, - SO,, - HCI, - NH3, - CO, signal is therefore determined by the proton concentration The degree of dissociation, a,reaches a value of unity even for the weakest acids at infinite dilution; in Fig 11.1 are given the concentration regions in which electrolytes are completely dissociated It then follows that the sensitivity of the electrolytic conductance detector is identical for low hetero-atom concentrations 185 11.2.1 ElCD background current The detector background current is determined by the dissociation of water (the ion-product of water is lo-’, at 25 “C, see equation (11.11)) and by the presence of ionic impurities in water If “conductance” water is employed, then the detector background current is very low When ion exchangers are used, a certain concentration of ions is present in the water and the background current is correspondingly increased, As follows from equation (11.13), the conductance of water plays a role at low eluted substance concentrations and there is a change in the detector linearity For this reason, the addition of ppm of HCl during measurement has been proposed [ ] ; however, this method cannot change the shape of the log SE‘CD/log c curve and, moreover, it increases the background current 11.2.2 ElCD response The detector response is the integral of over the elution time, A t As follows from equation (11.11), the detector response is proportional to the concentration of the eluted substance, c, and depends on its properties, i.e., on the dissociation constant of the corresponding acid or base, when the measurement is carried out under otherwise constant conditions (the vessel constant, Q, must not change) The E l C D linearity depends on the amount of substance eluted In general, it is less than unity for small amounts of substances, as the overall conductance is determined by the dissociation of water in the concentration range lo-’ M At higher concentrations, the linearity is again lower than unity, as the degree of dissoc = only in the concentraciation, CI, is less than unity It holds that log SEICD/log tion range M TABLE 11.4 SOLUBILITY PRODUCTS OF SEVERAL SILVER A N D CALCIUM SALTS Salt Ks AgCl Ag,CO, Ag,SO, Ag,SO, Salt 1.1 x 10-10 6.1 x lo-’, 1.0 x lo-’’ 1.2 x Ks ~- ~~~~ ~~ CaCO, CaSO, CaSO, 4.8 x 1~ - ~ Soluble The linear dynamic range of the detector follows from equation (11.11) for 01 = In general the linear dynamic range decreases in the order C1 > S > N (Fig 11.2) 186 The selectivity of the ElCD is determined by interactions among the combustion products In the nitrogen detector mode with a Ni catalyst, a single basic product is formed and therefore the measuring selectivity is high In the oxidation detector mode, all the products formed are acidic and hence various salts are placed in the gaseous mixture stream in order to improve the selectivity When AgNO, is employed to remove HCl from the gas stream, interaction of sulphur dioxide and trioxide with Ag' ions also occurs, as follows from the solubility products (see Table 11.4) The TABLE 11.5 THE SELECTIVITY VALUES OF THE ELECTROLYSIC CONDUCTANCE DETECTOR [I 51 Signal ratio N IS NIP N/CI N/CH,OH Selectivity 2.3 x 103 2.2 x 8.0 x 103 104 103 5-s.ox Signal ratio Selectivity N/higher alkanes 5.0 X lo6 1.0 x 104 1.0 x lo4 a/s CP sulphur signal is considerably decreased as the combustion does not yield sulphur dioxide with 100%efficiency [6] (see Table 10.2) Sulphur dioxide forms a sparingly soluble compound and the measuring selectivity is poor in the presence of a large excess of carbon dioxide The selectivity for halogens is better as HCl is not trapped in CaO The selectivity values of the electrolytic conductance detector are summarized in Table 11.5 11.3 CONSTRUCTION OF THE ElCD The substances eluted from the separating column pass through a combustion space or a pyrolyzer [l] and enter a gas-liquid contactor in which reaction with water takes place The gaseous phase is separated in a separator and the electrolyte enters the measuring cell The cell is very small, having a volume of about 50 p1 [lo, 161 The electrolyte then enters a reservoir and passes through an ion exchanger back to the contactor (see Fig 11.3) As the measurement is based on a chemical reaction, the absorption surface and the flow-rate of reaction gas must be optimized In addition to selection of the frequency, attention must be paid to the temperature of the measuring cell and of the circulating solution, as the ionic conductances increase considerably with increasing temperature 187 The conductance measurements are carried out in a low-frequency circuit When the frequency is increased to the MHz region, it is possible to perform impedance measurements on solutions of very low conductance [7,16] On this principle are based high-frequency detectors used in liquid chromatography Measurement of the dielectric constant, based on a similar principle, has not found broad application [18] c I 10 FIG 11.3 Scheme of the electrolytic conductance detector 1151; - column effluent, - reactor tube, - furnace, - gas-liquid contactor, - transfer line, measuring cell, - water reservoir, - gas-liquid separator, - pump, 10 - ion exchanger mixed bed, 11, 12 - needle valves, 13 - vent 11.4 APPLICATIONS OF THE ElCD The electrolytic conductance detector is not one of the most widely used measuring devices in gas chromatography It is generally used for pesticide residue analysis, for pesticides containing sulphur, chlorine and nitrogen The minimum detectable amounts are in the nanogram range This detector has also been used for analyses of TABLE 11.6 EXAMPLES OF THE APPLICATION OF THE ELECTROLYTIC CONDUCTANCE DETECTOR Substance determined Material analyzed Lowest detectable amount Linear dynamic range 6- 100 ng 0.1 ng 0.1 ng 2-1000 ng Metal halides S, CI pesticides N pesticides CI pesticides Herbicides S-Triazine N-Nitrosamines 0.02-2 ppm foodstuffs Ref 16, 17 1-3, , 9, 14 13 8' 188 metal halides, separated gas chromatographically A survey of the applications given in Table 11.6 It can be generally stated that the electrolytic conductance detector is a very simple measuring device, its design ranging from a universal type [12] to a highly specific nitrogen detector 11.5 LITERATURE Cochrane W P., Wilson B P., Greenhalgh R.: J Chromatogr 75, 207 (1973) Coulson D M.: J Gas Chromatogr 3, 134 (1965) Coulson D M.: J Gas Chromatogr 4, 285 (1966) Dolan J W., Hall R C.: Anal Chem 45, 2198 (1973) Jones P., Nickless G.: J Chromatogr 73, 19 (1972) Martin R L., Grant J A,: Anal Chem 37, 644 (1965) McCarthy W J., Lazarus M L.: Chem Instrum 1, 299 (1969) Palframan J F., McNab J., Crosby N T.: J Chromatogr 76, 307 (1973) Patchett G G.: J Chromatogr Sci 8, 155 (1970) 10 Piringer O., Pascalau M.: J Chromatogr 8, 410 (1962) 1 Piringer O., Tataru E., Pascalau M.: J Gas Chromatogr 2, 104 (1964) 12 Polesuk J., Howery D G.: J Chromatogr Sci 11, 226 (1973) 13 Purkayastha R Cochrane W P.: J Agric Food Chem 21, 93 (1973) 14 Rhoades J W., Johnson D E.: J Chromafogr Sci 8, 616 (1970) 15 Selucky M L.: Chromatographia 5, 359 (1972) 16 Tesatik K., Kaliib P.: J Chromatogr 78, 357 (1973) 17 Itiro T., Kiyoteru 0.: 2.Anal Chem 262, 346 (1972) 18 Winefordner J D., Glenn T H.: Advan Chromatogr 5, 263 (1968) INDEX acetylene 60, 93, 94 acids 165, 179 aliphatic 56, 110 carboxylic 179 miscellaneous 101 affinity, electron 72,73,77,79,83,93, 108, 113 air 46, 88, 92, 97 pollution 159, 176 alcohols 44, 56, 90, 93, 98, 110, 143 aldehydes 44, 143, 165 179 alkali metals 105ff 107 110ff, 120 alkanes, fluoro 89 americium 66, 80 aniines 83, 90, 101 amino acids 120 animonia 40, 89, 96, 108 amount, lowest detectable 34, 45, 56, 143, 187 analysis, trace 77 antimony 105 applications 56, 57, 78, 82B, 93, I O l f f , 120, 131, 143, 187 (see also contents) argon 40, 45, 46, 64, 75, 76, 78, 79, 96 arsenic 105, 108 Awe 83, 157 bases 165 benzene 29, 110 substituted 107, 108, 115 Reroza 151 blood 83, 84, 120 Bowman 151 capacity, heat 42, 43, 55 carbon 73 dioxide 45, 46, 56, 75, 78, 102 disulphide 20, 21, 57, 77, 84, 88, 91, 159 monoxide 40, 75, 143 tetrachloride 77, 78, 88, 93 niisc compounds S7, 84, 88, 93 (see also hydrocarbons) carbonyl 94 cell 51, 52, 70, 80, 81 diffusion 45, 46, 53 flow-through 43, 53, 5 semi-diffusion 43, 53 cesium 66, 80 charge, space 65 71, 119 chemiluminescence, intensit) of 149 chlorides 84, 1 chlorine 73, 107, 113 114, 116, 168 containing substances 165, 175, 178 chloroforni 77, 78 chromatography, liquid 82, 101 plasma 89 preparative 31 thin-layer 82, 101 coefficient, recombination 70, 74 combustion, hest of I5 conductance, of electrolytes 181 - I83 equivalent 184 ionic 184 conductivity, thernial 39 40 42-46, 49 constant, dissociation 182 time 26-28, 30, , 47, 51-56, 111 convection, gaseous 41, 46 53 coulometer, reaction 167 Coulson 181 cross-section, absorption 125 I27 collision 71 electron capture 60 excitation 134 ionization 22,36,60,61,64,75,78 80, 127 current, background 23,24,43,61,71,74- 76, 82, 92, 110-112, 114, 117, 118, 127, 135, 136, 141, 151 156, 170 185 electrolytic 165, 169 generating 173, 174 ionization 21, 59, 71, 72, 88ff, 92, 94, 96, 100, 105, 106, 108- 110 112- 114 117, 119, 125, 126, 134 190 curve, calibration 28 detectors (see also contents) catalytic 89 cross-section 62 discharge 57 electron capture 57, 62, 65, 72ff, 105, 159 electron mobility 62 flame ionization 21, 23, 32, 57, 64, 65, 84, 87ff, 105, 110, 113, 118, 159 flame photometric 57, 145ff helium (argon) 62, 64, 71, 105, 133ff ionization 59ff, 131 photo-emission I photo-ionization 62 105, 123ff thermal conductivity 25, 39, 39ff, 159 therniionic 62, 64, 65, 71, 1@5R', 157, 159 dilutcr, logarithmic 29, 30 distribution, concentration 30 drugs 83, 121 efficiency, current 168 ionization 61, 95 photoionization 125 Eisentraut 80 electrode, collecting 64, 98, 100, 107, 119, 141 shape 98 esters 44, 143 ethane 88, 93, 110 ethers 44, 90, 94, 98 evaporator, diffusion 29 Faraday laws 169 field, electric, intensity of 142 filament 48, 50ff filter, interference 158 flame 157ff diffusion 157 pre-mixed 157 shielded I58 62, 126, 135 139, garlic 83 gas, carrier IS, 20,22,23,27, 30-32, 43-47, 49, 68 71, 75, 79, 80, 83, 91, 96, 97, 117, 118, 128, 138, 140, 156 combustion 155, 156 Row-rate of 17, 20 22, 24-28, 30, 34, 41, 43-48, 53, 54, 80, 91, 94 -98, 110, 111, 114, 117-119, 155, 156, 172, 186 permanent 56, 79, 102, 131, 142 solubility of, in water 183 Geiger-MLiller curve 99, 119 gold 80 Goretti 162 halides 56, 84, 98, 107, 111, 115, 187 halogens 89, 91, 105, 107, 108, 115 147 I6S, 181 helium 40, 45-47, 61, 68, 73, 75, 79, 96 herbicides 84 Huyten 145 hydrocarbon5 71, 75, 78, 79, 87-94, 101, 109, 110, 120 chlorinated 56, 143 n-alkql-aromatic 44 hydrogen 40, 43-45, 47, 60, 61, 70, 73, 75, 79, 80, 87-89, 91, 92, 95, 105, 109-111, 114 sulphide 57, 84 hydroxyl 89, 90, I insecticides 83, 84 ionization 59ff, 64, 68, 74, 80, 82, 87, 83, 91, 105, 106, 109, 112 mechanism 64, 66, 63, 87, 88ff, 107 probability 125 Jrntzsch 57 ketones 78, 143, 165, 179 methyl 44 light, emitted, measurcment of 114 linearity 31, 32, 56, 77, 94, 115, 139, 153, 154, 171, 185 lindane 77 Maggs 80 mechanism, detector 59, 68, 72, 79, 80, 87, 90ff, 94, 95, 105, l06ff, 109, 113-115, 123, 145 melting point 115 metals, heavy 148, 159, 162 methane 40, 75, 78, 79, 88, 93, 110 methyl radical 89, 102 multi-regression 94 neon 68, 75 nickel 61, 65-67, 80, 81 191 nitrogen 23, , 40, 45-47, 56, 60, 61 63, 67, 70, 71, 73, 75, 78, 79 88 91, 96 97, :02, 105, 108, 115-117, 119, I81 containing substances 176, I73 oxides 40, 56, 60, 103, 108 113, 177 nitrile 94 noise 34-36, 43, 45, 50, 92, 97, IGO, 11 I , 119 142, 152, 156 170 olefins SO, 56, Otte 57 oxygen 40, 56, 70, 73, 74- 76, 79, j i i 94,97, 101, 103 ~ 89, I pair, ion 69 peak, elution, area of 28, 94, 95 elution, height or 21, 28 elution, inversion 45 -47 76 114, I IS elution, \ i ; l t I i of IS, 21, 24, 27, 28, 47 Penning efl’ect 134, 138 pesticides , 84, 101, 116, 120, 121, 150, 151 159, 160, 175, 179, 187 chlorinated 78, 187 phenols 84, 179 phosphorus 105, 108, 1 , 113-117, 119 containing substances 146 photomultiplier I58 photon flur 130 picolines 89 I’iringer 18 I plastic, fluorinmxi 54 platinum 89 plutoniurn 66, 80 polarography 169 pulse 169 Possanzini I62 potcntial, ionization 60 75, 79, 87 106, 107, 109 111, 113 excitation 133 pressure 29, 87, 90, 52 partial 115, 117, 118 vapour 114, I 15 pronietheuni 66, 67, 80 p d s c frequency , 81 quenching of radiation 149 range, linear dynamic ? I , 33, 45, , 76, 77 79, 80, 82, 85, 94, 115, 116, 128, 139, I S ? 153,171, 185 rccombination 69R, 72, 80, 89, 90, 106, 107, 119, 125, 142, 153 response, relative molar f , 91 Rijnders 145 Rossi 159 scandium 65, 80 sensitivity 31,43, 45, 46, 49, 56, 67, 77, 80 81, 95, 107, 116, 119 140, 155, 171 selectivity 36, 77, 95, 107, 116-1 18, 128, 140, 155, 171, 186 si!ylaied samples 98, 101, 119 Smith 83 source, ionization 6.5, 66ff photon 67, 130 radioactive 65, 80, 82 o! 65 /I 65 66, 74, 80, 133, 142 y 65 spectrometry, mass 89 spectruni, emission, of heteroatonis 147 state, nietastahle 64, 69, 71, 79, 133, 134 steroids 83, 101 strontium 65 styrene 101 sulphur 73, 89 91, 101, 105, 108, 1 , 115, 168,181 dioxklc 57, 108, 145, 159, 168 oxides 111 containing substances 146, 159, 160, 175, 178 sulphides 84, 112 I tempernture 34, 39, 42, 43-501l’, 65, 67, 76, 80, 83, 91, 95, 101, 105, 108, 109, 111, 114, 115, 118, 156, 175, 186 flame 110ff, 117-119, 154 thermistor 41, 48, 50, 55 theoretical plate 28 height equivalent to 17, 20 number of 17, 21, 22 t j i w , elulion 17, 21, 26, 28, 34, 43 retentioli 17, 21, 22 trmsparence optical 129, 130 transistor 41, 48, 54 t r:i ns mod ti la t o I 57 tritium 65, 65, 79, 80 urine 83, I20 192 Versino 159 volume, effective detector 22, 25-28, 31, 47, 51, 69, 72,79,80-83, 106, 108, 111, 172 dead 107 retention 17 water 74, 79, 83, 84, 89, 102, 120 xenon 64 yttrium 65