Immunoassay Screening of Lysergic Acid Diethylamide (LSD) and its Confirmation by HPLC and Fluorescence Detection Following LSD ImmunElute Extraction
Journal of Analytical Toxicology – April 01, 2002
Source: OpenAlex
Summary
Only 27% of the 48 urine samples initially flagged as positive for lysergic acid diethylamide (LSD) were confirmed through high-performance liquid chromatography (HPLC-FLD). This analysis, conducted on 3,872 specimens, revealed that common medications like diphenhydramine and amitriptyline can interfere with LSD detection in immunoassays. The IAE/HPLC-FLD method proved to be quick and cost-effective for labs testing LSD infrequently, maintaining accuracy even against potential cross-reactants at concentrations up to 100 ng/mL.
Abstract
In all, 3872 urine specimens were screened for lysergic acid diethylamide (LSD) using the CEDIA DAU LSD assay. Forty-eight samples, mainly from psychiatric patients or drug abusers, were found to be LSD positive, but only 13 (27%) of these could be confirmed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD) following immunoaffinity extraction (IAE). Additional analysis for LSD using the DPC Coat-a-Count RIA was performed to compare the two immunoassay screening methods. Complete agreement between the DPC RIA assay and HPLC-FLD results was observed at concentrations below a cutoff concentration of 500 pg/mL. Samples that were LSD positive in the CEDIA DAU assay but not confirmed by HPLC-FLD were also investigated for interfering compounds using REMEDI HS drug-profiling system. REMEDI HS analysis identified 15 compounds (parent drugs and metabolites) that are believed to cross-react in the CEDIA DAU LSD assay: ambroxol, prilocaine, pipamperone, diphenhydramine, metoclopramide, amitriptyline, doxepine, atracurium, bupivacaine, doxylamine, lidocaine, mepivacaine, promethazine, ranitidine, and tramadole. The IAE/HPLC-FLD combination is rapid, easy to perform and reliable. It can reduce costs when standard, rather than more advanced, HPLC equipment is used, especially for labs that perform analyses for LSD infrequently. The chromatographic analysis of LSD, nor-LSD, and iso-LSD is not influenced by any of the tested cross-reacting compounds even at a concentration of 100 ng/mL.