Browsing by Author "Davies Bronwen"

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    Open Access
    Development of a GC-MS method to determine toxic alcohols and their metabolites in postmortem blood
    (2024) Grevel, Carl; Vuko, Loyiso; Davies Bronwen
    The intentional and accidental ingestion of toxic alcohols represents a health care and potential public health concern within South Africa. Household and industrial antifreezes and brake fluids contain ethylene glycol (ETG) and diethylene glycol (DEG), which cause toxicity within humans. Other toxic alcohols such as 1,4-butanediol (1,4-BD) and propylene glycol (PGL) also show toxicity within the human body. Some of these analytes have previously been implicated in cases of fatal poisoning. However, the extent to which toxic alcohols contribute to death in South Africa is yet to be determined, as these are not routinely investigated in forensic toxicological analysis of biological samples. The purpose of this study was to modify and characterise a gas chromatography-mass spectroscopy (GC-MS) method for the quantitative determination of ETG, DEG, 1,4-BD, PGL, and the toxic metabolite of ETG, glycolic acid (GCA), in postmortem whole blood samples at the Forensic Toxicology Unit (FTU) in the Western Cape, South Africa. We describe the alteration of an existing method that examines most of these target analytes among others by Meyer, Weber and Maurer (2011), utilising a lower quantity of N,O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA) and post-mortem whole blood rather than plasma. The method was characterised according to parameters of calibration model, limit of detection, limit of quantification, bias, precision, processed sample stability, and carryover. Linearity was observed for all analytes between 25– 100 µg/mL with preliminary limits of detection at 25 µg/mL. Preliminary limits of quantification were 25 µg/mL for 1,4-BD, and 50 µg/mL for ETG, PGL, GCA and DEG. Recovery was calculated at ~40% for all analytes, and processed sample stability was calculated to be acceptable for up to 72 hours. The developed method was applied to several post-mortem cases of toxic alcohol ingestion at the Observatory Forensic Pathology Institute (OFPI). In conclusion, the method for the determination of toxic alcohols in post-mortem samples was successfully developed and characterised for a government forensic toxicology laboratory in the Western Cape. Future work will include the validation of this method to streamline analytical determination of the morbidity and mortality related to toxic glycols in the Western Cape
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    Open Access
    Investigating the role of routine drug analyses in survivors of sexual offences admitted to the clinical forensic unit at Victoria Hospital
    (2024) Peters, Casey; Mader, Jade; Davies Bronwen
    Introduction: Toxicological analysis is an important component of drug-facilitated sexual assault (DFSA) investigations, as it allows for identification and interpretation of substances involved. Currently, forensic toxicological analyses are not routinely provided to DFSA survivors in South Africa. The aim of this study was to investigate the utilisation and applicability of a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for common drugs of abuse in cases of suspected drug facilitated sexual offences. Methods: Blood and urine samples from 17 consenting adult survivors, who reported to the Clinical Forensic Unit at Victoria Hospital (August 2022 – December 2022) in Cape Town, South Africa, were analysed using a validated LC-MS/MS method targeting 31 common drugs of abuse. Samples were prepared for analysis using a Waters Ostro® pass-through plate extraction for blood and simple dilution extraction for urine. Case histories were obtained from participants by the attending medical practitioner using a standardised data collection sheet. Results: Majority of the participants reported to the clinic within 24 hours after the alleged offence (64.7%). Several participants reported consuming alcohol (64.7%), medicinal drugs (23.5%), or recreational drugs (35.3%) prior to, or at the time of the offence. A psychoactive drug was detected in 58.8% of cases. Methamphetamine (and its metabolite amphetamine) were the most frequently detected analytes (41.2% and 35.3% of cases, respectively). Conclusion: Accurate and reliable toxicological analysis is vital in processing DFSO cases. This study determined that the analytical method is useful in DFSO cases as over half of the participants tested positive for at least one drug, and most self-reported recreational drugs were included in the panel. Recommendations include expanding the panel to include additional pharmaceutical drugs and incorporating ethanol analysis into the routine workflow to provide comprehensive testing to survivors of DFSO and support the criminal justice system in South Africa.