Differential Pulse Stripping Voltammetric Determination of Hydroquinone and Catechol with Moylbdovanadophosphoric Heteropolyacid-Poly-1,2-Diaminobenzene Modified Carbon Paste Electrode

Moylbdovanadophosphoric heteropolyacid-poly-1,2-diaminobenzene modified carbon paste electrode was prepared by electrochemical polymerization with scanning rate of 0.100 V·s-1 in an electrolyte containing moylbdovanadophosphoric heteropolyacid and 1,2-diaminobenzene for 20 cycles in the potential range from 0.800 to -0.800 V. As shown by the result of CV study on the electrochemical behaviors of CC and HQ at the modified electrode, a pair of oxidation and reduction peaks was found for each of the 2 compounds. It was shown by DPSV study that sensitive 2nd derivative stripping peaks was observed at the potential of 0.140 V for HQ and 0.288 V for CC, giving a potential difference of 0.148 V. Linearity range for HQ and CC were same to be 1.50×10-7-7.50×10-4mol·L-1, with detection limits (3S/N) of 6.80×10-8mol·L-1. Based on these facts, DPSV method was used in the determination of HQ and CC in simulated water sample, giving values of recovery in the range of 94.0%-106.0%.