Amperometric electrochemical detection of pyrroloquinoline quinone in high-performance liquid chromatography

The electrochemistry of pyrroloquinoline quinone (PQQ) enables its reduction and oxidation at a variety of electrode surfaces. Two methods of PQQ quantitation are described using amperometric electrochemical detection after HPLC separation. In one method a single electrode is used to reduce PQQ in the eluant stream and is sensitive to as little as 10 pmol of material. The second method is a dual electrode method that takes advantage of the reversible nature of the PQQ redox cycle and though only half as sensitive as the single electrode method, it is more specific. The advantages of the method lie in its simplicity, sensitivity, and low cost.