Evaluation of solid-phase microextraction in combination with gas chromatography (SPME-GC) as a tool for quantitative bioanalysis

Solid-phase microextraction in combination with capillary gas chromatograph y and a nitrogen-phosphorus detector as a bioanalysis tool was investigated . Lidocaine and three of its metabolites were used as model compounds, and human plasma and urine samples were used in this evaluation. Carbowax-divin ylbenzene, polyacrylate, and polydimethylsiloxane fibers were tested. Absor ption times were studied for all analytes separately. Carbowax- divinylbenz ene fiber gave highest recovery in plasma samples compared to other fibers. Effects of temperature, addition of salt and agitation of the sample were studied. Recovery from plasma was improved by 2-4 times at pH 9 compared to pH 3. This is due to analytes not: charged at high pH. Recovery from water was 2-4 times higher than from plasma using Carbowax-divinylbenzene coated fiber. This is due to protein binding of analytes in plasma. Chromatograph ic selectivity was high and all metabolites were well separated. Calibratio n curves were linear for all metabolites in human plasma and urine in the r ange 0.035-7.7 mu M for lidocaine and 2,6-xylidine while 0.1-3.5 mu M for g lycinexylidide (GX) and monoethylglycinexylidide (MEGX). Precision, measure s as relative standard deviation, was less than 15% and accuracy was in the range 80-115%. Limits of quantitation using plasma were 0.035 mu M (8 ng/m L), 0.035 mu M (4 ng/mL), 0.100 mu M (18 ng/mL), and 0.100 mu M (21 ng/mL) for lidocaine, 2,6-xylidine, GX, and MEGX, respectively. (C) 2000 John Wile y & Sons, Inc.