Determination of pentazocine in human whole blood and urine by gas chromatography/surface ionization organic mass spectrometry.

Pentazocine has been found to be measurable with much higher sensitivity by gas chromatography (GC)/surface ionization (SI) organic mass spectrometry (OMS) than by the conventional GC/electron ionization (EI) mass spectrometry. The compound was extracted from human whole blood and urine with Sep-Pak C(18) cartridges before analysis by GC/SIOMS; recoveries were > 96.6% for both samples. The calibration curves were linear in the range 6.25-100 ng ml(-1) and the detection limits were 500 pg ml(-1) of a sample by selected ion monitoring (SIM) with GC/SIOMS. The intra- and inter-day relative standard deviations for the determination of pentazocine in whole blood and urine were not greater than 9.6%. The sensitivity for pentazocine obtained by SI-SIM was about 60 times higher than that obtained by EI-SIM. To validate the present GC/SIOMS method for pentazocine, whole blood and urine samples collected from two volunteers 1-6 h after intramuscular injection of 15 mg of pentazocine were analyzed. The concentrations were 13.5-59.3 ng ml(-1) for whole blood and 0.39-4.00 microg ml(-1) for urine.