NCJ Number
159717
Journal
Canadian Society of Forensic Science Journal Volume: 28 Issue: 4 Dated: (December 1995) Pages: 261-269
Date Published
1995
Length
9 pages
Annotation
The Elisha immunoassay technique was tested on whole blood samples for potential application in forensic toxicology blood screening programs.
Abstract
Kits tested included cocaine and metabolites, cannabinoids, phencyclidine (PCP), amphetamines, and opiates. The Elisha process is an enzyme linked immuno sorbent assay system for the analysis of drugs in various tissues. Antibodies are bound to a 96 well plate where there is competition between the free drug from the sample and the drug bound to the enzyme for a fixed antibody. The sample is added to a well, followed by enzyme conjugate, and allowed to incubate at room temperature. The cells are washed with distilled water. A substrate reagent is then added, followed by another incubation period. After the second waiting period, a stopping reagent is added, and the plate read at 450 nm. The plate reader measures absorbance for each cell as a one-step process that requires no further sample manipulation. Positive or negative decisions for unknowns are made by absorbance shift comparison to standard sample readings. Detection limits were found to be lower using the Elisha technique compared to standard enzyme multiplied immunoassay (EMIT) procedures used in Royal Canadian Mounted Police Toxicology sections. In addition to an improvement in sensitivity, it was noted that the procedure itself saved analysts time, since the extraction steps required for EMIT analysis were eliminated. The technique was found to be inherently flexible, in that the choice of matrix or tissue for analysis could be easily adapted to a simple standard procedure. 7 tables and 14 references