Determination of fentanyl in human plasma by head-space solid-phase microextraction and gas chromatography-mass spectrometry.

A head-space solid-phase microextraction (HS-SPME) method coupled to GC-MS was developed to extract fentanyl from human plasma. The protein binding was reduced by acidification and, eventually, the sample was deproteinized with trichloroacetic acid. The parameters influencing adsorption (extraction time, temperature, pH and salt addition) and desorption (desorption time and temperature) of the analyte on the fibre were investigated and validated for method development. The developed method proved to be rapid, simple, easy and inexpensive and offers high sensitivity and reproducibility. Linear range was obtained from 0.1 ng/ml to 2 microg/ml. The limit of detection was 0.03 ng/ml while an inter-day precision of less than 5% (n=15) could be achieved. The method has been applied for the determination of fentanyl in plasma samples after application of 50 microg/h Duragesic fentanyl patch.