| |
Published:
Journal of Analytical Toxicology,
ISSN 0146-4760,
Volume 26, Number 7, October 2002,
pp. 504-512
Validation of a Microtiter Plate ELISA for Screening of
Postmortem Blood for Opiates and Benzodiazepines
for Cocaine*
Philip Kemp[1], Gary Sneed[1], Tom Kupiec[2], and
Vina Spiehler[3]
[1]Office of the Medical Examiner, Oklahoma City, Oklahoma; [2]Analytical Research
Laboratories, Inc., Oklahoma City,
Oklahoma; and [3]Spiehler & Associates, Newport Beach, California
The object of this study was
to evaluate the suitability of the Neogen Corp. microtiter plate enzyme-linked
immunoassays (ELISA) for opiates and benzodiazepines for screening of postmortem
blood. Ninety postmortem whole blood specimens were obtained from drug-involved
deaths which had been screened and confirmed positive for opiates and/or benzodiazepines.
Forty negative specimens were obtained from non-opiate-involved deaths. Specimens
were tested using the Neogen Opiates Group and Neogen Benzodiazepines Group
microtiter plate ELISA assays. No matrix effects were found for whole blood
in these assays and a dilution of 1:5 was chosen to facilitate pipetting and
to bring the IC50 of the microtiter plate ELISA assay within the range of opiates
and benzodiazepines encountered in medical examiner specimens. True positive,
true negatives, false positives, and false negatives were determined and graphed
for the ELISA results against gas chromatography–mass spectrometry (GC–MS),
gas chromatography–nitrogen-phosphorus detection and case histories. From
these graphs and the ROC curves, the optimal cut-off for the Neogen Opiates
Group ELISA was found to be between 20 and 50 ng/mL morphine equivalents and
the optimum cut-off for the Neogen Benzodiazepines Group ELISA was between 20
and 50 ng/mL temazepam equivalents. The Neogen Opiates Group ELISA had a sensitivity
of 95.2% ± 2.7% and a specificity of 92.2% ± 3.4% versus GC–MS
at a cut-off of 20-ng/mL cut-off and a sensitivity of 88.8% ± 3.9% and
specificity of 96.8% ± 2.1% versus GC–MS at a 50-ng/mL morphine
equivalents cut-off. The Neogen Benzodizepines Group ELISA had a sensitivity
of 100% ± 1.3% and a specificity of 94.6% ± 2.9% versus GC–MS
(20-ng/mL temazepam equivalents cut-off) and a sensitivity of 95.8% ±
2.5% and specificity of 98.2% ± 1.8% versus GC–MS at a 50-ng/mL
cut-off. Reproduction
of editorial content of this journal is prohibited without publisher’s
permission.
This
article is available in its entirety by fax for $40.00 each.
Visa, MasterCard and AMEX accepted.
To
order electronically click here
or call: 847-647-2900 ext. 1323
or fax request to: 847-647-1155.
To order multiple copies click here.
Please indicate JAT
volume and issue along with page numbers. |
|
Home | Subscribe
| Current Issue | Back Issues
| Search | Advertise | Other Publications
| |
