Electromembrane surrounded solid phase microextraction: A novel approach for efficient extraction from complicated matrices

In the present work, electromembrane surrounded solid phase microextraction (EM-SPME) is introduced for the first time. The organic liquid membrane, which consists of 2-nitrophenyl octyl ether (NPOE), was immobilized in the pores of a hollow fiber (HF) and the basic analytes migrated in an electrical field from aqueous sample solution through the liquid membrane and into aqueous acceptor phase and then they were adsorbed on the solid sorbent, which acts as the cathode. Effective parameters such as composition of organic liquid membrane, pH of donor and acceptor phases, applied voltage and extraction time were optimized for extraction of amitriptyline (AMI) and doxepin (DOX) as model analytes and figures of merit of the method were investigated in pure water, human plasma, and urine samples. To extract the model analytes from 24 mL neutral sample solution across organic liquid membrane and into aqueous acceptor phase, 120 V electrical potential was applied for 20 min and finally the drugs were adsorbed on a carbonaceous cathode. Regardless of high sample cleanup, which make the proposed method suitable for the analysis of drugs from complicated matrices, extraction efficiencies in the range of 3.1–11.5% and good detection limits (less than 5 ng mL−1) with admissible repeatability and reproducibility (intra- and inter-assay precisions ranged between 4.0–8.5% and 7.5–12.2%, respectively) were obtained from different extraction media. Linearity of the method was studied in the range of 2.0–500.0 ng mL−1 and 5.0–500.0 ng mL−1 for AMI and DOX, respectively and coefficient of determination higher than 0.9947 were achieved. Finally, the proposed method was applied for the analysis of AMI and DOX in real samples.