Immunochemical extraction and detection of LSD in whole blood

Abstract

Polyclonal antibodies raised against the hallucinogenic drug, lysergic acid diethylamide (LSD), were used to detect and extract drug from whole blood samples. An indirect ELISA was used to detect as little as 1 pg of total drug in 25 μl blood. The limit of detection of the immunoassay, calculated from the mean−3 SD was 39 pg/ml. The analytical recovery of LSD (2.5–0.2 ng/ml) from whole blood was 102–113%. Within-run CVs for LSD spiked in blood at 1.25, 0.16 and 0.04 ng/ml were 5.6, 3.1, and 8.9%, respectively ( n=4). There was an overall decrease in precision when whole blood was used in place of urine, due to the increased complexity of the matrix. However, using this technique LSD was calibrated in blood in the sub-ng/ml region of forensic interest. Immunoaffinity extraction was used to isolate LSD from blood and urine samples. The affinity support was prepared by covalently attaching anti-LSD antibodies to Protein A-coated agarose beads. No pre-treatment of the sample was required other than the addition of neutral buffer. Sub-ng/ml concentrations of LSD were routinely extracted from blood and urine samples with greater than 80% recovery of drug. This technique, which could be used to extract LSD from blood and urine samples prior to confirmatory drug analysis, could be completed in about 10 min.