Voltammetric determination of urinary 1-hydroxypyrene using molecularly imprinted polymer-modified screen-printed carbon electrodes

A two step non-competitive affinity method for the trace determination of 1-hydroxypyrene (1-OHP) using a disposable molecularly imprinted polymer (MIP) modified screen-printed carbon electrode (MIP-SPCE) has been developed. The MIP was synthesized according to a novel strategy, which is described, and is capable of rebinding the phenolic analyte, 1-hydroxypyrene (1-OHP), from high pH aqueous organic media, via ionic interactions. In the first step of our method 1-OHP was accumulated at the MIP-SPCE from 35% aqueous methanol containing 0.014 M NaOH and 0.14 M NaCl, at open circuit. In the second step, the resulting SPCE with accumulated 1-OHP was then transferred to fresh, clean phosphate buffered aqueous methanol, and subjected to cyclic voltammetry (CV) or differential pulse voltammetry (DPV). The latter technique proved to be more sensitive at detecting 1-OHP, with a limit of detection of 182 nM and a linear range to 125 mu M on unmodified electrodes. The possible effects of interference by related phenolic compounds in the MIP-SPCE of I-OHP were investigated. Finally the method was evaluated by carrying out 1-OHP determinations on spiked human urine samples; the recovery of 1-OHP was 79.4% and the coefficient of variation was found to be 7.7% (n=4) using a separate MIP-SPCE for each determination. Therefore, the performance data suggests that the method is reliable at the concentrations examined in this study. The method was found to be superior to the direct determination of 1-OHP in human urine by DPV alone, which was greatly affected by interference from uric acid.