Introduction to Modern Liquid Chromatography, Third Edition part 84 ppsx

... as acetonitrile or acetone to a homogenized portion of a vegetable sample allows the extraction of pesticides into the solvent (step 2 of Fig. 16.7). Subsequent addition of salt (step 3) leads to ... extractors and thimbles are available for mg-size samples. The analyte concentration, the necessary mass to obtain a representative sample, and the chromatographic detector sensitivity, tog...

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... 651 13.10.3 Liquid- Chromatography Modes for Polymer Analysis, 653 13.10.3.1 Size-Exclusion Chromatography, 653 13.10.3.2 Interactive Liquid Chromatography, 653 13.10.3.3 Liquid Chromatography under Critical ... RPC- 5 Chromatography, 623 13.5.3 Hydrophobic Interaction Chromatography, 624 13.6 Separation of Carbohydrates, 625 13.6.1 Hydrophilic Interaction Chromatography, 625 1...

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... Snyder and J. J. Kirkland, Introduction to Modern Liquid Chromatography, 2nd ed., Wiley-Interscience, New York, 1979, pp. 34–36. 46. Reviewer Guidance. Validation of Chromatographic Methods, Center ... Chromatogr. A, 1119 (2006) 140. 22. J. C. Giddings, Dynamics of Chromatography, Part 1, Principles and Theory, Dekker, New York, 1965. 23. G. Guiochon, in High-Performance Liquid...

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... in flow rate from 2.0 to 1.0 mL/min (not shown) results in an insignificant increase in resolution (to R s = 1.2), while run time is doubled to 10 min. Alternatively, the particle size can be reduced, ... (called ‘‘phase-optimized liquid chromatography’’ or POPLC ® from Bischoff). Experiments with individual columns define sample retention for each column type, and it is then possible t...

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... Section 9.2.2.5: (1) to clean the column between sample injections, (2) to shorten run time, or (3) to improve separation by adjusting selectivity for different parts of the chromatogram. Because ... that the sample may be too nonpolar for separation with the usual RPC conditions. In such cases an acetonitrile/buffer gradient can be replaced by a gradient from acetonitrile to a less-p...

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... proportional to the accessible surface area of the packing (Section 5.2.1). For smaller molecules (<1000 Da), particles with pore-diameters of 8 to 12 nm permit free access of solutes into the pore ... surface of the particle (which represents < 1% of the total surface and column capacity within the pores). In order to achieve adequate column capacity, retention, and column efficie...

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... elution strategy is to bind proteins at pH values between 7 and 8, followed by elution with a step or gradient to pH values between 4 and 5, in order to convert histidine residues to the ionized form. An ... silanols. Poly(2-hydroxyethyl aspartamide) is a stationary phase that was designed expressly for HILIC [77]; it is prepared by incorporating ethanolamine into a coating of polysuc...

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... found to be powerful chiral selectors with complementary enantioselectivity (different enantioselectivities and elution orders), leading to CSPs based on vancomycin [111], teicoplanin [112], ristocetin ... antibiotic columns, exemplified by enantiomer separations of Z-Ala (top) and 5-methyl-5-phenylhydantoin (bottom). Experimental conditions: Ristocetin A, 20:80 methanol/0.1% triethylammon...

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... screwdriver or other metal tool, to avoid damaging the pump head. Do not use the piston to pry out the seal because the piston is likely to break. As you remove the seal, be sure to note how the seal ... sapphire piston. • Inspect the piston for any scratches or defects. A simple way to highlight any problems is to hold a laser pointer up to the end of the piston, which will cau...

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... (arrow). counter to automatically record the number of injection cycles, so as to allow the remaining rotor seal life to be estimated. When viewed in cross section, the grooves of the rotor shown in ... split and distorted peaks in Section 17.4.5.3); otherwise, it may be necessary to replace the column. Before putting the system back into service, consider if steps need to be taken...

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