A bipotentiostat based 4-electrode detection system for HPLC analysis

With the assist of a microcomputer interfacing, a bipotentiostat incorporat ed 4-electrode detection system was developed as a versatile electrochemica l detector for HPLC. An amperometric chromatogram and two three-dimensional chromatovoltammograms characterizing the electrochemical characteristics o f analytes can be obtained in a single chromatographic run. By following th e three operation modes developed, both the oxidizable and reducible analyt es contained in sample solutions can be determined. The analytical capabili ty of the 4-electrode detection system was demonstrated by the analysis of solutions containing hydroquinone, catechol and ascorbic acid. From the cal ibration graphs obtained, linear coefficients better than 0.9992 were found for hydroquinone and catechol in a concentration range of 1.0 x 10(-4) to 1.0 x 10(-7) M, and a linear coefficient of 0.9929 was found for ascorbic a cid in a concentration range of 1.0 x 10(-4) to 1.0 x 10(-6) M. The detecti on limits (based on S/N = 3) found were about 1.0 x 10(-7) M for hydroquino ne and catechol and was 1.0 x 10(-6) M for ascorbic acid.