Methamphetamine in antemortem blood and urine by radioimmunoassay and GC/MS.
Methamphetamine abuse is increasing and methamphetamine is second only to alcohol as a positive finding in cases submitted to the San Diego Sheriff's Crime Laboratory. In general, whole blood specimens are submitted more often than urine. A modified version of a commercially available radioimmunoassay, Coat-A-Count (CAC) Methamphetamine, was investigated as a screen for methamphetamine in whole blood and urine. The assay was modified by using 100 microL of sample, making up standards in whole beef blood, extending the incubation time to 2 h or overnight, and using a cutoff reference of 50 ng/mL methamphetamine. The detection limit for the CAC Methamphetamine kit was 20 ng/mL methamphetamine in whole blood. The CAC Methamphetamine results were compared to Abuscreen Amphetamine High Specificity results and to gas chromatography/mass spectrometry (GC/MS) quantitation of amphetamine and methamphetamine for 157 positive and 48 negative blood specimens. With the CAC Methamphetamine assay there were 2 false negatives detected, both less than the 50 ng/mL cutoff level. There were 12 (6%) false positives with the CAC Methamphetamine assay and 29 (14%) false positives with the Abuscreen Amphetamine assay. Of the positive samples, 95% contained only methamphetamine, with an average concentration of 308 ng/mL, range 25-2030 ng/mL.
Rasmussen
S
S
San Diego Sheriff's Crime Laboratory, California 92110.
Cole
R
R
Spiehler
V
V
D005069:Evaluation Studies as Topic; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008694:Methamphetamine / Q000097:blood / Q000378:metabolism* / Q000652:urine; D011863:Radioimmunoassay / Q000379:methods / Q000592:standards; D012015:Reference Standards; D013997:Time Factors
D008694:Methamphetamine