Measurement of benzodiazepines in urine by liquid chromatography-tandem mass spectrometry:confirmation of samples screened by immunoassay

摘要

Background: Liquid chromatography linked to tandem mass spectrometry (LC/MS/MS) provides the ability to identify a rangenof benzodiazepines in accordance with European Union criteria and is an attractive method for the confirmation ofnbenzodiazepines following immunoassay screening.nMethods: An LC/MS/MS method to detect and quantitate the six most common benzodiazepines/metabolites (diazepam,nnitrazepam, nordiazepam, oxazepam, temazepam and 7-aminonitrazepam) was developed together with a qualitativenscreening method for a further 11 benzodiazepines/metabolites. These methods were used for confirmation of 250 urinensamples submitted for routine drug screening by immunoassay for benzodiazepines (100 samples positive for anbenzodiazepine, assay cut-off .200 msg/L).nResults: The lower limits of detection and quantitation were less than 2.5 and 5 mg/L for the six most commonnbenzodiazepines. Recoveries ranged between 97% and 102% and calibration curves were linear to at least 4000 mg/Ln(r ¼ 0.99). Intra and inter-assay imprecision were ,10% (n ¼ 10) and ,20% (n ¼ 15), respectively. Confirmation ofnbenzodiazepines using LC/MS/MS was achieved for 89% of the immunoassay-positive urine samples. Of the immunoassay-nnegative urine samples, 31% of these demonstrated a benzodiazepine using LC/MS/MS.nConclusion: The validated LC/MS/MS method developed is effective for the confirmation of immunoassay screening resultsnfor benzodiazepines. The lower limit of detection and assay specificity offers a longer window of detection and more detailednclinical information compared with immunoassay screening.