|SOFT - TIAFT 1998||Scientific Session 7||Friday October 9, 1998|
|ANALYSIS OF LSD AND METABOLITES IN BIOLOGICAL SAMPLES BY IMMUNOAFFINITY PURIFICATION FOLLOWED BY GC/MS/MS COMBINED WITH NICI|
|Asbjørg S. Christophersen, Dag Helge Strand and Unni Johansen|
National Institute of Forensic Toxicology, P.B. 495 Sentrum N-0105 Oslo, Norway
|A sensitive and highly specific method for the analysis of LSD in urine has been developed. In order to obtain clean extracts satisfactory for the chromatographic analyses, monoclonal LSD-antibody (CEDIA LSD Assay®)-resin was mixed with urine samples directly into the extraction columns. After incubation at room temperature for 30 minutes, the urine matrix was washed out with phosphate buffer and water. LSD was released from the antibodies by methanol elution. After evaporation, LSD and the internal standard (IS) LSD-d3 were derivatized with heptafluorobutyrylimidazole (HFBI), followed by GC/MS/MS detection combined with NICI. Methane and argon were use as ionization and collision gases, respectively. Based on multiple reaction monitoring of several ions, e.g. m/e 499 (LSD), 502 (IS) as parent ions, producing 456 as daughter ions (both from LSD and IS), LSD down to 0.1 pmol/ml could be detected from 2 ml urine sample.
The metabolite nor-LSD could also be isolated using the same immunoaffinity reagent followed by derivatization and GC/MS/MS-detection and NICI, while iso-LSD and iso-nor-LSD had both very low antibody affinity.
The same procedure was tested for the analysis of LSD in whole blood at similar concentration levels. After precipitation of red cells with cold ethanol followed by centrifugation, the supernatant was incubated with LSD-antibody-resin. The cleaner sample extracts obtained both for urine and blood samples after immunoaffinity purification, both improved sensitivity and simplified the instrument maintenance procedures.