Optimization of generic conditions for electromembrane extraction of basic substances of moderate or low polarity

Generic electromembrane extraction (EME) methods were developed and optimized for basic analytes of moderate or low polarity, employing prototype conductive vial EME equipment. Two generic methods, B1 and B2, were devised for mono- and dibasic compounds with distinct polarity windows: 2.0 < log P < 6.0 for B1 and 1.0 < log P < 4.5 for B2. In B1, 10 μL of 2-nitrophenyl octyl ether served as the liquid membrane, while B2 utilized 10 μL of 2-undecanone. Both methods involved the acidification of 125 μL of human plasma samples with 125 μL of sample diluent (0.5 M HCOOH for B1 and 1.0 M HCOOH for B2). The acceptor phase consisted of 250 μL of 100 mM HCOOH. Extraction was conducted for 30 min with agitation at 800 rpm, employing an extraction potential of 100 V for B1 and 50 V for B2. A set of 90 pharmaceutical compounds was employed as model analytes. Both B1 and B2 demonstrated high recoveries (40%-100%) for the majority of model analytes within their respective polarity windows. Intra-day precision was within 2.2% and 9.7% relative standard deviation. Both extraction systems exhibited stability in terms of current, matrix effect values were between 90% and 109%.