Application of a Validated UPLC–MS-MS Method for the Determination of Diphenidol in Biological Samples in 15 Authentic Lethal Cases

Abstract

Abstract Diphenidol (DPN) is a nonphenothiazinic antivertigo and antiemetic drug that has been widely used in clinical practice in China because of its good antivertigo curative effect, minimal side effects and high safety. In recent years, there have been some cases of sporadic suicide and accidental poisoning related to DPN. Hence, a validated method for the determination of DPN in biological samples by ultra-high-performance liquid chromatography–tandem mass spectrometry (UPLC–MS-MS) was developed. The method is characterized by the use of a simple, fast and inexpensive liquid–liquid extraction (LLE) for sample preparation, a rapid run time (5 min) and a low required sample volume (0.1 mL or 0.1 g). The lower limits of quantitation (LLOQs) were 0.05 ng/mL and 0.3 ng/g for blood and liver tissue, respectively. The method was shown to be linear over a concentration range of 0.05–200 ng/mL (blood) and 0.3–400 ng/g (liver). The accuracy was in the range of 92.77–112.75%. The relative standard deviations of the intraday and interday imprecisions were in the range of 3.22% to 12.17%, and the recoveries were in the range of 58.75–95.27%. Furthermore, the method was successfully applied to the detection and quantification of DPN in 15 real forensic cases. The postmortem concentration range of heart blood was 0.87–99 μg/mL.