On-chip pulsed electromembrane extraction as a new concept for analysis of biological fluids in a small device

In the present work, an on-chip pulsed electromembrane extraction technique followed by HPLC-UV was developed for the analysis of codeine, naloxone and naltrexone as model analytes in biological fluids. The chip consisted of two channels for the introduction of the donor and acceptor phases. The channels were carved in two poly (methyl methacrylate) plates and a porous polypropylene membrane, which is impregnated by an organic solvent separating the two channels. Two platinum electrodes were mounted on the bottom of these channels and a pulsed electrical voltage was applied as an electrical driving force for the migration of ionized analytes from the sample solution through the porous sheet membrane into the acceptor phase. Using the pulsed voltage provided effective and reproducible extractions and could successfully overcome the disadvantages of applying constant voltages. Effective parameters of on-chip pulsed electromembrane extraction such as chemical composition of the organic solvent, applied voltage, pH of the donor and acceptor phases, flow rate and pulse duration were optimized using one-variable-at-a-time method. Under the optimized conditions, the model analytes were effectively extracted from different matrices and good linearity in the range of 10.0-500.0 μg L−1 was achieved for calibration curves with coefficients of determinations (R2) higher than 0.997. Extraction recoveries and%RSDs were obtained in the ranges of 28.6-32.9% and 2.15-3.8, respectively. Also, limits of detection were obtained in the ranges of 5-10 μg L−1 and 2-5 μg L−1 in plasma and urine samples, respectively.