Published: Journal of Analytical Toxicology, ISSN 0146-4760, Volume 26, Number 4, May/June, pp. 226-232

Screening for Basic Drugs in 2-mL Urine Samples by Dual-Plate Overpressured Layer Chromatography and Comparison with Gas Chromatography-Mass Spectrometry
Anna Pelander*, Ilkka Ojanperä, Johanna Sistonen, Ilpo Rasanen, and Erkki Vuori
Department of Forensic Medicine, P.O. Box 40, FIN-00014 University of Helsinki, Finland

A dual-plate overpressured layer chromatography (OPLC) method was evaluated for broad-scale screening of basic drugs in 2-mL autopsy urine samples. Extraction was carried out by mixed-mode solid-phase extraction, and identification was based on automated comparison of corrected Rf values (hRfc) and in situ UV spectra with library values by dedicated software. The day-to-day precision of hRfc values was good in both OPLC1 and OPLC2 systems with median relative standard deviations of 2.4% and 3.4%, respectively. Both Rf and hRfc values were independent of the amount of analyte (0.5–10 µg) applied to the plate. Detection limits were determined for 47 drug substances in 2-mL urine samples, and they varied between 0.05 and 3.5 mg/L with a median of 1.0 mg/L. The performance of OPLC was evaluated by analyzing 30 autopsy urine samples by both OPLC and gas chromatography–mass spectrometry (GC–MS). The majority of findings by OPLC were in agreement with GC–MS. Some substances with low concentrations were not detected by OPLC, whereas GC–MS failed to detect a few polar substances. The OPLC method thus provides an alternative for current planar and column liquid chromatographic drug screening methods with the possibility of lowering detection limits by using a larger sample size.

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