Amperometric biosensor precision improvement: application to organophosphorus pesticide determination

An approach for precision improvement in organophosphorus pesticide determination was developed, applied and characterized. The enzyme organophosphorus hydrolase was employed as a specific agent for electrode surface modification, and the pulsed amperometric detection for 66.6 ms was applied for the hydrolysis product detection. Pulsed electrochemical cleaning, i.e. oxidation at a very positive potential (+1.4 V vs. Ag, AgCl) was applied every 233 ms for 166.6 ms for elimination of the fouling effect, which degrades the determination precision. By this way a RSD of 0.41% at 40 μmol L−1p-nitrophenol determination was achieved after 10 determinations, instead of 43.93% without the pulsed cleaning application.