Determination of amitraz in canine plasma by solid-phase microextraction–gas chromatography with thermionic specific detection

A simple and rapid analytical method is presented for the determination of amitraz in canine plasma samples using solid-phase microextraction (SPME) and gas chromatography with thermionic specific detection (GC-TSD). The best conditions for the SPME procedure were: direct extraction on a polydimethlysiloxane (PDMS) fiber with 100-μm film thickness; 400 μl of sample plasma matrix modified with 4 ml sodium borate solution (0.01 mol l−1, pH 6.5); extraction temperature 70 °C, with stirring at 2500 rpm for 45 min. The method was linear between 20 and 400 ng ml−1 with regression coefficients corresponding to 0.998 and coefficient of the variation of the points of the calibration curve lower than 15%. The lowest limit of quantification (LOQ) for amitraz in plasma was 20 ng ml−1. This LOQ was determined as the lowest concentration on the calibration curve in which the coefficient of variation was lower than 15%. The proposed method was applied to determine amitraz concentrations in canine plasma to look for toxicity after treatment with amitraz in a dipping bath.