On-fiber derivatization for direct immersion solid-phase microextraction Part I: Acylation of amphetamine with pentafluorobenzoyl chloride

On-fiber derivatization has been used for solid-phase microextraction (SPME ) with gas chromatography in order to increase the extractability and detec tability. Amphetamine, which has been used as a model compound, was derivat ized with pentafluorobenzoyl chloride that was loaded on the fiber prior to the direct immersion of the fiber into the sample. The extraction performa nce of amphetamine with and without on-fiber derivatization has been compar ed. As the derivative possesses properties other than its parent compound, its partitioning between the polydimethylsiloxane coated fiber and sample m atrix is different, i.e., with on-fiber derivatization a yield of 55% could be obtained in 55 min while without derivatization a yield of 40% has been obtained after a 105 min extraction. As the derivatization reagent is very suitable for electron capture detection, this detection system gave a fact or of about 1000 better response for the derivative compared to flame ioniz ation detection. Optimization of the method is presented for buffer solutio ns to show its benefits. Good linearity (r = 0.9991) for a 50 pg/mL to 5 ng /mL range has been obtained. The applicability for urine analysis has short ly been demonstrated.