The number of new psychoactive substances (NPS) available is constantly increasing, making it difficult for toxicology laboratories to keep screening methods up to date. Full scan high-resolution mass spectrometry (HRMS) is a versatile technique which allows for progressive updating of spectral databases to increase the scope of screening. It also allows for retrospective screening of data-specifically, reprocessing of data files using an updated spectral database without the need for re-extraction or reanalysis.The coronial case reported here illustrates the application of retrospective processing of HRMS data in the detection of emerging NPS. A 28-year-old male with a history of illicit drug use was found deceased at home. Initial routine screening of the post-mortem peripheral blood identified only methylamphetamine, amphetamine and trace amounts of lorazepam. A compound with an accurate mass and isotope ratio consistent with the opioid AH-7921 was also detected in the liquid chromatography (LC)-HRMS screen; however; the retention time and mass spectrum did not match the library. Further investigation confirmed the compound to be U-47700, another opioid and structural isomer of AH-7921. Several months later, after additional NPS had been added to the in-house HRMS database, retrospective screening of the HRMS data was performed, revealing the presence of designer benzodiazepines, diclazepam and flubromazepam as well as the psychedelic drug 2,5-dimethoxy-4-chloroamphetamine (DOC). Quantitative analysis gave the following results in peripheral post-mortem blood: U-47700 (330 μg/L), diclazepam (70 μg/L), flubromazepam (10 μg/L), methylamphetamine (290 μg/L) and amphetamine (150 μg/L) (DOC not quantitated). These substances, along with lorazepam and etizolam, were also confirmed in the post-mortem urine and an investigation into blood and urinary metabolites was carried out. All analyses were performed using the same LC-quadrupole-time of flight method. The cause of death was aspiration (of gastric content into airways and lungs) due to mixed drug toxicity.

Tapentadol is a centrally acting synthetic analgesic which is prescribed for the treatment of a range of chronic pain conditions. Its use in treating various pain conditions is increasing and, as with other opioids, it has the potential to be abused. We describe a three-stage incorporation of tapentadol into validated screening and quantitative methods through: (i) addition of retention time/mass spectral data to a database, (ii) qualitative validation and (iii) quantitative validation. This represents an efficient and flexible approach to the incorporation of new compounds of interest to existing screening methods. Tapentadol was analyzed in blood and serum samples using alkaline liquid-liquid extraction with identification and quantitation by liquid chromatography/time-of-flight mass spectrometry. In a series of six post-mortem cases where tapentadol was detected but was not a primary causative factor in death, blood concentrations ranged from 0.01 to 1.0 mg/L. In two cases where tapentadol was a significant contributor to death, post-mortem blood concentrations were 1.7 and 3.9 mg/L. In one of these fatal cases, ante-mortem blood and serum were also analyzed. The tapentadol concentration in the post-mortem blood was 30% higher than in the ante-mortem blood after a post-mortem interval of 13 days, indicating some potential for post-mortem redistribution. The measured ante-mortem blood:serum ratio was 1.7, and is the first such ratio to be reported. Other drugs were detected in almost all cases, with the majority being prescription analgesics, sedatives and antidepressants. The number of cases in which tapentadol has been detected has increased in recent years, highlighting the importance of screening for this drug in forensic toxicological laboratories.

Biochemical analysis of the vitreous humor from the eye is an accepted accessory test for post-mortem investigation of cause of death. Modern biochemical analyzers allow testing of a range of analytes from a sample. However, it is not clear which analytes should be requested in order to prevent unnecessary testing (and expense). The means and standard deviation of the values obtained from analysis of the vitreous humor for sodium, potassium, chloride, osmolality, glucose, ketones (β-hydroxybutyrate), creatinine, urea, calcium, lactate, and ammonia were calculated from which the contribution of each analyte was reviewed in the context of post-mortem findings and final cause of death. For sodium 32 cases were regarded as high (more than one standard deviation above the mean), from which 9 contributed to post-mortem diagnosis [drowning (4), heat related death (2), diabetic hyperglycemia (2), and dehydration (1)], but 25 low values (greater than one standard deviation below the mean) made no contribution. For chloride 29 high values contributed to 4 cases--3 drowning and 1 heat-related, but these were all previously identified by a high sodium level. There were 29 high and 35 low potassium values, none of which contributed to determining the final cause of death. Of 22 high values of creatinine, 12 contributed to a diagnosis of renal failure. From 32 high values of urea, 18 contributed to 16 cases of renal failure (2 associated with diabetic hyperglycemia), 1 heat-related death, and one case with dehydration. Osmolarity contributed to 12 cases (5 heat-related, 4 diabetes, 2 renal failure, and 1 dehydration) from 36 high values. There was no contribution from 32 high values and 19 low values of calcium and there was no contribution from 4 high and 2 low values of ammonia. There were 11 high values of glucose, which contributed to the diagnosis of 6 cases of diabetic hyperglycemia and 21 high ketone levels contributed to 8 cases: 4 diabetic ketosis, 3 hypothermia, 3 ketosis of unknown cause, and 2 alcohol related deaths. A high lactate was identified in 25 cases, which contributed to 1 case with a diagnosis of metformin toxicity (1), but none of the 22 low lactate values contributed. The results of this audit have been used to reduce vitreous biochemistry test requests for sodium, osmolality, glucose, ketones, urea, and creatinine in most cases. Critical appraisal of each part of the post-mortem process should be undertaken to provide evidence to justify any investigative methods used in an autopsy.

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