Evaluation of full-scanning GC/ion trap MS analysis of NIDA drugs-of-abuse urine testing in urine.

Abstract

Analytical methods developed for the Finnigan MAT ITS40 gas chromatograph-ion trap mass spectrometer (GC/MS) were evaluated for the confirmation of drugs-of-abuse in urine. The specific drugs evaluated are those listed by the National Institute on Drug Abuse (NIDA): 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (9-carboxy-THC), benzoylecgonine (BE), codeine and morphine, phencyclidine (PCP), amphetamine, and methamphetamine. Drugs were extracted from urine using solid-phase columns, separated by capillary gas chromatography, and analyzed by ion trap mass spectrometry following electron impact ionization. All drugs except PCP were derivatized prior to analysis. The full scan limits of detection (LOD), quantitation (LOQ), and linearity were 2.5, 5.0, and 1000 ng/mL, respectively, for 9-carboxy-THC; 37, 75, and 5000 ng/mL for BE; 50, 100, and 2500 ng/mL for the opiates; 0.25, 0.50, and 500 ng/mL for PCP; and 50, 100, and 5000 ng/mL for the amphetamines. The limits of detection (LOD) and limits of quantitation (LOQ) met the minimum criteria for the signal-to-noise (S/N) ratio and spectral match criteria for drug identification. Absolute LODs and LOQs (in ng/mL) for the ITS40 based on single ion monitoring of blank urines were: 0.8 and 2.0 for 9-carboxy-THC; 8.9 and 25 for BE; 3.3 and 9.6 for codeine; 6.2 and 16.7 for morphine; 0.25 and 0.32 for PCP; 0.7 and 2.0 for amphetamine; and 2.4 and 5.7, for methamphetamine, respectively. The coefficient of variation ranged from 5 to 10%, and analytical recoveries were in the range of 90-114%. The ion trap mass spectrometer permits full scan identification of drugs while maintaining analytical LOQ that are below NIDA guidelines, and has equivalent or better detection limits to quadrupole analyzers for high sensitivity applications.