Potentiometric detection of carboxylic acids, phosphate esters, and nucleotides in liquid chromatography using anion-selective coated-wire electrodes.
An all-solid-state ion-selective membrane electrode incorporating a lipophilic anion exchanger was used in a flow-through potentiometric detector for the LC determination of organic anions of biological interest. Different metabolic intermediates (mono-, di-. and tricarboxylic acids, sugar phosphates, and nucleotides) were detected sensitively after separation on a pellicular anion-exchange chromatographic column. The electrode was coated by directly casting the electroactive mixture on a glassy carbon support of 3 mm diameter and used in a wall-jet-type flow cell. The analysis conditions were optimized to obtain both efficient separation and sensitive detection. Calibration curves showed a logarithmic dependence on the injected concentration for concentrations higher than 5.0 x 10(-5) M and a linear dependence for injected concentrations below this value. Under isocratic conditions, detection limits of 5.0 x 10(-7) M (25 pmol) were attained when a sodium hydroxide solution was used as an eluent. No suppressor system was needed in this case. The relative standard deviation for consecutive injections was 0.3% (n = 15), and the electrode lifetime was at least 2 months. The utility of potentiometric detection is further demonstrated in a gradient elution separation for single-run analysis of a synthetic mixture of biochemical compounds containing carboxylic acids, phosphate esters, and nucleotides.
Picioreanu
S
S
Kluyver Laboratory for Biotechnology, Delft University of Technology, The Netherlands.
Poels
I
I
Frank
J
J
van Dam
J C
JC
van Dedem
G W
GW
Nagels
L J
LJ
D000465:Algorithms; D002264:Carboxylic Acids / Q000737:chemistry*; D002853:Chromatography, Liquid; D004566:Electrodes; D009711:Nucleotides / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D011199:Potentiometry; D015203:Reproducibility of Results
D002264:Carboxylic Acids; D009711:Nucleotides; D010710:Phosphates