Simultaneous Screening and Quantitation of Drugs and Their Metabolites in Postmortem Samples by Liquid Chromatography-High-Resolution Mass Spectrometry: Does It Provide Any Benefits?

Abstract

Screening of postmortem blood and urine samples is used to identify compounds that may have contributed to an individual's death. Toxicologically significant compounds detected by the screen are then quantitated in blood to determine their likely effect upon death. In most laboratories, this is a two-step process. This study compares an established two-step screening and quantitative processes, utilizing a gas chromatography-mass spectrometry (GC-MS) screen followed by quantitation by GC-MS or high-performance liquid chromatography with diode array detection (HPLC-DAD), with a novel method utilizing liquid chromatography-high-resolution mass spectrometry (LC-HRMS). The LC-HRMS assay is able to screen postmortem blood and urine samples and simultaneously measure the concentration of toxicologically significant compounds in postmortem blood. Screening results of 200 postmortem blood samples and 103 postmortem urine samples by LC-HRMS and GC-MS showed that LC-HRMS detected key compounds in 125% more instances and there was a 60% increase in the number of compounds detected. Quantitative values generated using the LC-HRMS assay were within ±10% of values obtained using the established methods by GC-MS or HPLC-DAD. A retrospective analysis of turnaround times pre- and post-adoption of LC-HRMS showed a decrease for all of the compounds in the analysis, including a 43% reduction for free morphine and codeine, a 50% reduction for amphetamine and a 37% reduction for cocaine. Combining screening and quantitation reduced staffing requirements by 2 days for opiate quantitation and 1 day for most other analytes. The adoption of LC-HRMS also significantly reduced sample volume requirements. These results demonstrate that the adoption of LC-HRMS for simultaneous screening and quantitation delivered significant benefits in comparison to the two-step procedure.