|SOFT - TIAFT 1998||Scientific Session 7||Friday October 9, 1998|
|DETECTION OF UNDERIVATIZED LYSERGIC ACID DIETHYLAMIDE (LSD) IN URINE USING GAS CHROMATOGRAPHY/ION TRAP TANDEM MASS SPECTROMETRY|
|Jason H. Sklerov, Thomas Z. Bosy, Kathryn S. Kalasinsky and Cheryl A. Ehorn*|
Office of the Armed Forces Medical Examiner, Division of Forensic Toxicology, Armed Forces Institute of Pathology, Washington, D.C., USA
|In the Department of Defense (DoD) urinalysis drug-testing program, 190,000 urine specimens are tested monthly for lysergic acid diethylamide (LSD). Although LSD usage is known to be popular in some branches of the armed forces, less than 0.01% of the urine samples are determined to be positive for LSD as compared to 7% for the other drugs tested. The ability to routinely detect the low levels of LSD in a cost-effective manner would greatly assist the drug deterrence program for this illicit substance.
To that end, a gas chromatography/tandem mass spectrometry (GC/MS/MS) method was developed using an internal ionization ion trap MS for the detection of underivatized LSD. Following solid phase extraction of 5mL of urine, extracts are injected into a temperature-programmable injector with a 0.5mm I.D. direct-injection insert. The injection port is optimized to reduce analyte loss by injecting at low temperatures followed by rapid heating. Collision-induced dissociation (CID) of the isolated 323 m/z parent ions of LSD and lysergic acid methylpropylamide (LAMPA, internal standard) is achieved by resonant dissociation for 30msec at 0.61v. The product ions 280, 222, and 196 m/z are monitored for both LSD and LAMPA with 222 m/z as the quantifying ion.
The method was linear over the concentration range 20-2000 pg/mL with a correlation coefficient of 0.999. The observed limit of detection was 20 pg/mL with an 80 pg/mL limit of quantitation. Intra-day stability assessed over 12 injections gave a %CV=5.0. The method was successfully applied to both DoD Quality Control Laboratory samples and previously confirmed LSD positive samples.
Ion trap MS/MS has been demonstrated as a favorable tool for low level drug confirmation in biological samples. It provides the necessary sensitivity with lower complexity of operation over alternate instrumental methods.