Direct determination of diazepam and its glucuronide metabolites in human whole blood by μElution solid-phase extraction and liquid chromatography–tandem mass spectrometry

Development of a simple and sensitive HPLC-MS/MS method for determination of diazepam in human plasma and its application to a bioequivalence study

“…In previous studies to develop a bioanalytical method to quantitate diazepam in human plasma, samples were prepared using the protein precipitation (PP) method or solid-phase extraction (SPE) method. [5][6][7][8] However, due to insufficient removal of impurities from the sample when using the PP method, the analytical method with samples prepared using the PP method may not be appropriate for the routine analysis of a large number of samples. [5,6] The SPE method is a complicating and timeconsuming sample preparation procedure.…”

“…[5,6] The SPE method is a complicating and timeconsuming sample preparation procedure. [7,8] Therefore, in this study, a liquid-liquid extraction (LLE) method was used to effectively remove endogenous substances and thus, improve the efficiency of analyzing a large number of samples for human pharmacokinetic research. Our developed method satisfied all of the MFDS and USFDA guidelines for validating a bioanalytical assay.…”

“…Although protein precipitation (PP) and solid phase extraction (SPE) methods have been previously used to extract the analyte, these methods are laborious and thus, may not be the best for routine analysis when processing a large number of plasma samples. [6][7][8] The extraction recoveries and matrix effects of diazepam following extraction at three QC concentrations were 81.92-86.63% and 88.15-93.54% (n = 6), respectively ( Table 3). The extraction recovery and absolute matrix effect of IS were 87.61% and 89.71%, respectively, at 200 ng/mL (Table 3).…”

“…[2] Previous studies have proposed several analytical methods using high-performance liquid chromatography (HPLC) with an ultraviolet (UV) [3,4] or mass spectrometry (MS) [5][6][7][8][9] detection to determine the concentrations of diazepam administered by various routes including nasal spray, rectal gel, intramuscular injection, and oral formulations. [10][11][12][13][14][15] However, these previously developed analytical methods have been associated with several limitations including inadequate sample preparation due to difficulty in removing impurities, [5] inadequate sensitivity (a lower limit of quantitation [LLOQ] up to 50 ng/mL), [6] labor-intensive sample preparation process, [7] the need for a relatively large volume of plasma (≥ 100 μL) for analysis, [8] and long retention times (≥ 8 min). [9] Therefore, a new bioanalytical method to quantitate diazepam has been needed to improve those limitations.…”

Current trends in environmental analysis of human metabolite conjugates of pharmaceuticals

“…In fact, most studies used some form of analyte pre-concentration (e.g., SPE cartridge or micro-elution well plate), with few exceptions: estrogen glucuronide analysis in soil [20], resveratrol conjugates isolated from heart, liver, and brain tissues [21,22]; and alcohol glucuronides assayed from urine by serial dilution for immunoassay [23]. Both cartridges and well plates used HLB stationary phase to isolate and concentrate conjugates.…”