| Abstract
| - An all-solid-state ion-selective membrane electrode incorporating a lipophilic anion exchanger was used in aflow-through potentiometric detector for the LC determination of organic anions of biological interest. Differentmetabolic intermediates (mono-, di-. and tricarboxylicacids, sugar phosphates, and nucleotides) were detectedsensitively after separation on a pellicular anion-exchangechromatographic column. The electrode was coated bydirectly casting the electroactive mixture on a glassycarbon support of 3 mm diameter and used in a wall-jet-type flow cell. The analysis conditions were optimized toobtain both efficient separation and sensitive detection.Calibration curves showed a logarithmic dependence onthe injected concentration for concentrations higher than5.0 × 10-5 M and a linear dependence for injectedconcentrations below this value. Under isocratic conditions, detection limits of 5.0 × 10-7 M (25 pmol) wereattained when a sodium hydroxide solution was used asan eluent. No suppressor system was needed in this case.The relative standard deviation for consecutive injectionswas 0.3% (n = 15), and the electrode lifetime was at least2 months. The utility of potentiometric detection is furtherdemonstrated in a gradient elution separation for single-run analysis of a synthetic mixture of biochemical compounds containing carboxylic acids, phosphate esters, andnucleotides.
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