Enhancing gel electromembrane extraction using glycine-doped agarose to mitigate electroendosmosis flow: application to tramadol extraction from biological specimens.

This study involves incorporating glycine into agarose to effectively eliminate electroendosmosis (EEO) effects in gel electromembrane extraction (G-EME) of tramadol (TMD) from biological samples. The development of a glycine-modified agarose membrane for EEO-free tramadol extraction represents a significant advancement in analytical chemistry with far-reaching societal implications. By eliminating the confounding effects of electroendosmosis and eschewing the use of harmful organic solvents typically employed in electromembrane procedures, this environmentally friendly method enhances the accuracy and precision of tramadol quantification in biological matrices. The operational procedure consists of the extraction tramadol, from 10 mL aqueous sample solution (pH 6.0), as the donor phase (DP), transferring it into membrane (pH 5.0); as the final step, it enters into an acceptor phase (AP, 700 μL, pH 4.0). The optimization of critical parameters, including the (w/v) percentage of agarose and glycine, the gel thickness, and the pH levels of the acceptor phase, gel, and donor phase, was conducted utilizing the one-factor-at-a-time methodology, while voltage, time, and stirring rate were optimized employing the design of experiment approach. Remarkably, under the optimized conditions, a satisfactory linear relationship was established within the range of 0.05-6 μg mL-1 (R2 = 0.9925), accompanied by a commendable limit of detection (LOD) amounting to 0.015 μg mL-1, with an extraction recovery rate of 94%. Finally, the proposed method was successfully applied to the determination of TMD in urine, plasma, and tablet samples.