Forensic laboratory validation of immunochromatography and gas chromatography/mass spectrometry methods for the detection of methamphetamine and amphetamine in postmortem urine specimens

Abstract

Identification of methamphetamine and its metabolite, amphetamine, both in biological and non-biological samples, is important in forensic toxicology practice. One of the key elements in forensic drug testing is the possibility to use inexpensive screening tests to obtain immediate presumptive results. In the present study the reliability of urine ABON® immunochromatography screening device for the detection of methamphetamine and amphetamine in postmortem urine samples was evaluated. The reliability of the test was assessed by comparing ABON® screening results with confirmatory gas chromatography/mass spectrometry (GC/MS). The analysed samples were 600 positive and 600 negative immunochromatographic results that were confirmed using GC/MS. GC/MS results were used as reference to determine sensitivity, specificity, false and true positives and negatives and positive and negative prediction values. Sensitivity of the ABON® device was 99% for methamphetamine in postmortem urine specimens. ABON® test was also specific enough (97%). Negative and positive predictive values were 99% and 97% respectively. In the GC/MS method, good chromatographic separation was obtained in the presence of licit and illicit drugs. The limit of detection and limit of quantification were equal to 5, 10 ng/mL respectively. The method was linear from 15–1500 ng/mL of methamphetamine and the coefficient of determination was 0.9915. Recovery efficiency was 94%. In conclusion, performance of the ABON® test device is adequate for presumptive determination of methamphetamine in forensic urine drug screening.