Use of gas chromatography/mass spectrometry with positive chemical ionization for the determination of opiates in human oral fluid

An analytical method for the simultaneous determination of codeine, morphine and 6‐acetylmorphine (6AM) in human oral fluid was developed. The method involves liquid‐liquid extraction in Toxitubes A®, derivatization with 99:1 (v/v) N,O ‐bis(trimethylsilyl)trifluoroacetamide (BSTFA)/trimethylchlorosilane (TMCS), and gas chromatography/mass spectrometry with positive chemical ionization (GC/PCI‐MS) determination. The detector response was linear over the concentration range 30–500 ng/mL with coefficients of correlation higher than 0.99. The precision was acceptable with coefficients of variation less than 7.5%. The limits of detection achieved were 0.7 ng/mL for codeine, 2.0 ng/mL for morphine, and 0.6 ng/mL for 6AM. The method proposed was applied to 80 oral fluid samples from opiates users, 98% of which were positive for the three analytes. Human oral fluid is a suitable biological fluid for the determination of opiates by GC/PCI‐MS. Copyright © 2006 John Wiley & Sons, Ltd.