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Abstract
A rapid method for the determination of cotinine concentration in plasma is described. Cotinine is extracted from plasma along with 2-phenylimidazole as an internal standard. Extraction is accomplished by solid phase extraction using BondElut C18 silica extraction columns. The extract is evaporated, reconstituted with mobile phase, and injected onto a reversed-phase C18 ion-pair column using an isocratic high performance liquid chromatograph. The mobile phase consists of acetonitrile and methanol in phosphate buffer (0.01M, pH 3.2) 7:13:80 (v/v/v) containing octanesulfonic acid (0.001 M). The flow rate was 1.5 mL/min. Absorbance was monitored at 260 nm. The detection limit is 5 μg/L for cotinine. The standard curve is linear from 0 to 1000 μg/L. The CVs at 40 μg/L and 100 μg/L are 7.4% and 4.8% respectively.