Combined microporous membrane-based liquid-liquid-liquid microextraction and in situ differential pulse voltammetry for highly sensitive detection of trimipramine

In this paper, a microporous membrane-based liquid-liquid-liquid microextraction and electrochemical analysis are used to purify, preconcentrate and detect ultra-trace amounts of trimipramine in biological fluids such as plasma and urine. For the microextraction of trimipramine, a porous polyethylene membrane was saturated with isoamyl benzoate. A phosphoric acid solution and an alkaline solution were used as the acceptor and source phase, respectively. The influence of effective parameters on both extraction efficiency and peak current of trimipramine on a multiwall carbon nanotube-modified carbon paste electrode was studied. The best results were obtained in a sample solution of 0.06 mol L-1 NaOH and an acceptor phase of 0.06 mol L-1 phosphoric acid at a rotation rate of 1200 rpm and a temperature of 65 degrees C over an extraction time of 20 min. The analyte was extracted from the source phase quantitatively with an enrichment factor of 16.3. Because of the memory effect, a new membrane was used for each extraction. The detection limit was 2.0 nmol L-1 trimipramine with an RSD of 4.3%. The method was found to be highly selective and sensitive for detecting trimipramine in biological fluids.