Verstraete A.G., Steyaert S.

Laboratory of Clinical Biology - Toxicology, University Hospital, De Pintelaan 185, B-9000 Gent, Belgium.

We evaluated the precision and the diagnostic performance of the Boehringer Mannheim CEDIA^® DAU LSD assay. The assay was performed in the semi-quantitative mode on a Hitachi 917 analyzer. It uses three reagents: antibody reagent (R1), enzyme donor reagent (R2) and enzyme acceptor reagent. Sample, R1, R2 and R3 volume were 18, 100, 100 and 140 µL respectively. The assay was calibrated semi-quantitatively using four calibrators with concentrations of 0, 0.5, 1.5 and 3.0 ng/mL of LSD. Within-run (n = 7) and day-to-day (n = 9) CV's of the semiquantitative values for the cutoff calibrator (0.5 ng/mL) were 3.7 and 3.8 % respectively. We analyzed 143 urine samples for LSD by CEDIA^®, DPC^® Coat-A-Count^® RIA and Behring EMIT^® II. Confirmation was performed by GC-MS, after extraction on Bond Elut Certify^® columns (detection limit 25 pg/mL). Ninety-four samples were negative by all methods. Twenty samples were positive by all immunoassays, 14 of which were confirmed by GC-MS. Three samples were positive by EMIT and CEDIA, but negative by RIA and GC-MS. Twenty-six samples were positive by EMIT alone, but not confirmed by GC-MS. The LSD CEDIA assay seems less specific than LSD RIA, but more specific than the EMIT LSD assay