A new platform for sensing urinary morphine based on carrier assisted electromembrane extraction followed by adsorptive stripping voltammetric detection on screen-printed electrode

Abstract

Electromembrane extraction (EME) coupled with electrochemical detection on screen-printed carbon electrode has been developed for the quantification of morphine in urine samples. Charged morphine molecules were extracted from an aqueous sample by applying an electrical potential through a thin supported liquid membrane (SLM) into an acidic aqueous acceptor solution (20µL) placed inside the lumen of a hollow fiber. Then, the acceptor solution was mixed with 20µL of NaOH solution (0.1M) and analyzed using screen printed electrochemical strip. Differential pulse voltammetry (DPV) peak current at 0.18V was selected as the signal and the influences of experimental parameters were investigated and optimized using Box–behnken design and also one-variable-at-a-time methodology as follows: adsorptive accumulation time, 40s; SLM, 2-nitrophenyl octyl ether+10% tris-(2-ethylhexyl) phosphate+10% di-(2-ethylhexyl) phosphate; pH of the sample solution, 6.0; pH of the acceptor solution, 1.0; EME time, 24min; EME potential, 90V and stirring rate, 1000rpm. The calibration curve which was plotted by the variation of DPV currents as a function of morphine concentration was linear within the range of 0.005–2.0µgmL−1. The limit of detection and the limit of quantification were 0.0015 (S/N=3) and 0.005µgmL−1, respectively. Finally, the proposed method was able to determine morphine simply and effectively at concentration levels encountered in toxicology and doping.