|SOFT - TIAFT 1998||Poster Session 4||Friday October 9, 1998|
EVALUATION OF AN LC/MS SYSTEM FOR THE DETERMINATION OF LSD, ISO-LSD, AND 2-OXO-3-HYDROXY-LSD IN URINE FROM LSD USERS|
Matthew H. Slawson, Carol L. O'Neal, Thomas C. Kupiec, Rodger L. Foltz and John M. Hughes*
Center for Human Toxicology, University of Utah, Salt Lake City, UT 84112, USA
|Lysergic acid diethylamide (LSD) is one of the most difficult drugs of abuse to detect by urinalysis because of the very low concentrations of the parent drug excreted in the urine. Several methods for confirmation of LSD in urine have employed GC/MS or GC/MS/MS. Instrumentation which utilizes tandem mass spectrometry (MS/MS) often produces an improvement in specificity and signal-to-noise ratio which can be important in measuring trace concentrations of drugs in biological tissues. However, the cost of MS/MS instrumentation is prohibitive for many toxicology laboratories. We report a relatively rapid and sensitive analytical method for the quantitation of LSD, iso-LSD and 2-oxo-3-hydroxy-LSD in urine using liquid chromatography and single-stage mass spectrometry (LC/MS). 2-Oxo-3-hydroxy-LSD is a recently identified metabolite of LSD that is generally present in urine from LSD users at higher concentrations than LSD. Iso-LSD is not a metabolite of LSD, but is often detected in the urine from an LSD user because of its presence as a contaminant in LSD sold on the street.
Internal standards (LSD-d3 and 2-oxo-3-hydroxy-LAMPA) were added to urine samples which were then subjected to solid-phase extraction and analyzed by electrospray LC/MS using a Hewlett-Packard series 1100 LC-MSD. Calibration curves for each analyte were linear from 50 pg/mL to 5000 pg/mL with correlation coefficients (r2) greater than 0.99. Quality control samples fortified with 250 pg/mL LSD quantitated within 20% of the target concentration with a coefficient of variation of 2.3%. Urine samples (n = 8) previously confirmed positive for LSD by GC/MS/MS have been analyzed using the above method. LSD concentrations for positive samples ranged from 102 - 844 pg/mL. Iso-LSD concentrations for positive samples ranged from 52 - 574 pg/mL. 2-Oxo-3-hydroxy-LSD concentrations for positive samples ranged from 203 - 4288 pg/mL.