Rapid determination of benzodiazepines, zolpidem and their metabolites in urine using direct injection liquid chromatography-tandem mass spectrometry.
Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully verified with human urine samples from drug users (n=21). Direct urine sample injection and optimized mobile phases were introduced for simple sample preparation and high-sensitivity with the desired separation.
Department of Chemistry, Yonsei University, Republic of Korea.
Yu-Dong
YD
Jeong
Forensic Science Division, Supreme Prosecutors' Office, Republic of Korea.
Min Kyung
MK
Kim
Forensic Science Division, Supreme Prosecutors' Office, Republic of Korea.
Sung Ill
SI
Suh
Forensic Science Division, Supreme Prosecutors' Office, Republic of Korea.
Moon Kyo
MK
In
Forensic Science Division, Supreme Prosecutors' Office, Republic of Korea. Electronic address: paxus@spo.go.kr.
Jin Young
JY
Kim
Department of Chemistry, Yonsei University, Republic of Korea. Electronic address: paengk@yonsei.ac.kr.
Ki-Jung
KJ
Paeng
D000525:Alprazolam / Q000031:analogs & derivatives / Q000652:urine; D001569:Benzodiazepines / Q000652:urine*; D002853:Chromatography, Liquid / Q000379:methods*; D005479:Flurazepam / Q000031:analogs & derivatives / Q000652:urine; D053593:Forensic Toxicology / Q000379:methods; D006801:Humans; D006993:Hypnotics and Sedatives / Q000652:urine*; D057230:Limit of Detection; D011725:Pyridines / Q000652:urine*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D014229:Triazolam / Q000031:analogs & derivatives / Q000652:urine; D000077334:Zolpidem
D006993:Hypnotics and Sedatives; D011725:Pyridines; D001569:Benzodiazepines; D014229:Triazolam; C032318:alpha-hydroxyalprazolam; C028638:alpha-hydroxytriazolam; D000077334:Zolpidem; C033473:didesethylflurazepam; D005479:Flurazepam; D000525:Alprazolam
Benzodiazepines; Direct injection; LC–MS/MS; Metabolite; Urine; Zolpidem