Electromembrane surrounded solid-phase microextraction using a stainless-steel wire coated with a nanocomposite composed of polypyrrole and manganese dioxide

Abstract

A nanocomposite was electrochemically synthesized from polypyrrole and manganese dioxide (PPy/MnO2) and deposited on a stainless-steel wire for use in electromembrane surrounded solid-phase microextraction (SPME). In order to evaluate the performance of the method, the antihistamines cyproheptadine (CYP) and ketotifen (KET) were selected as model analytes. To increase the selectivity of the method and to improve sample cleanup, an organic solvent was immobilized in the pores of the wall of a hollow fiber. The SPME fiber was placed in its lumen which was initially filled with the aqueous acceptor phase. The basic analytes (CYP, KET) were migrated, by applying an electrical field, from the aqueous sample solution through the liquid membrane into the aqueous acceptor phase. As a result, they are adsorbed by the solid sorbent which acts as the cathode. The composition of the organic liquid membrane, the pH values of the donor and acceptor phases, the applied voltages and the extraction times were optimized. Under optimal conditions, extraction recoveries are in the range of 26.8 to 46.9%, and detection limits of less than 1.1 and 0.7 ng mL−1 in water, urine and plasma samples were obtained by using GC with FID detection for KET and CYP, respectively. Response is linear in the range of 0.3 to 200 ng mL−1 in water, 1.2 to 200 ng mL−1 in urine and 1.0 to 200 ng mL−1 in plasma samples for CYP, and from 0.7 to 200 ng mL−1 in water, 1.4 to 200 ng mL−1 in urine and 1.2 to 200 ng mL−1 in plasma samples for KET. The method was applied to the analysis of CYP and KET in human urine and plasma samples, and satisfactory results were obtained.