ELECTROCHEMICAL DETECTION OF PYRROLOQUINOLINE QUINONE COUPLED WITH ITS CATALYTIC FUNCTION BY LIQUID-CHROMATOGRAPHY

Coenzyme pyrroloquinoline quinone (PQQ) was electrochemically detected with high sensitivity and high selectivity by employing its redox catalytic function in reversed-phase high-performance liquid chromatography. This catalytic reaction involves oxidative decarboxylation of glycine by PQQ and the reoxidation of the reduced PQQ by Fe(CN)63- to accumulate Fe(CN)64-, of which the electrochemical detection allows amplified detection of PQQ. Increase by two orders of magnitude of the current was achieved as compared with a direct reductive detection, at a reaction time of 3 min and a reaction temperature of 25-degrees-C. The detection limit was 0.2 pmol (10(-8) M, 20 mul). The present method was applied to quantification of PQQ in table vinegar, milk, and swine serum.