Simultaneous analysis of zolpidem and its metabolite in whole blood and oral fluid samples by SPE-LC/MS for clinical and forensic purposes

PurposeThe new analytical method of qualitative and quantitative determination of zolpidem and qualitative analysis of its main metabolite in blood and oral fluid samples was developed.Materials and methodsSample preparation was carried out using a polymeric ion-exchange sorbent in solid phase extraction (SPE). Analysis was realized using liquid chromatography with mass spectrometry detection (LC/MS). The method was validated in terms of few parameters. LOD, LOQ, linearity, precision, selectivity, ion suppression and stability were estimated.ResultsObtained method showed good linearity with determination coefficient (R2) of 0.9989 and 0.9998 for blood and oral fluid samples, respectively. LOD and LOQ of zolpidem were 0.2 ng/mL and 1.0 ng/mL, respectively, for both blood and oral fluid samples. SPE method recovery varies from 79.9 ± 12.6 to 104.1 ± 1.77 for blood sample and 80.2 ± 0.48 to 103.8 ± 1.51 for oral fluid sample. Samples collected from patients taking zolpidem with a prescription were analyzed. Detection of zolpidem was possible after 15 h from ingestion of 10 mg zolpidem tartrate in both types of samples.ConclusionThe developed method allows quantitation of zolpidem in therapeutic and subtherapeutic range as well as qualitative analysis of its main metabolite in blood and oral fluid samples. This method meets criteria required for bioanalytical applications and can be used for clinical and forensic purposes.