An overdose of insulin will produce a hypoglycaemic effect in the body, which may prove to be fatal.1 Insulin, used clinically in the treatment of diabetes, includes synthetic analogues such as Apidra®, Humalog®, Lantus®, Levemir®, Novorapid®. The ability to effectively identify and differentiate the various types of insulin can be very important to an investigation e.g. the presence of synthetic or exogenous insulin in a non-diabetic may be indicative of a poisoning attempt, while abnormally high levels of insulin (exogenous/synthetic or endogenous) in a victim could point to homicide or suicide.2 Commonly, clinical laboratories analyse insulin in blood by radioimmunoassay. In a forensic context, limited information is obtained via this technique thus highlighting the need for methodology that can provide greater sensitivity, specificity and robustness, and which is also capable of the unequivocal identification of the various insulin analogues at pmol levels — paramount for coronial investigations. The QE Plus Orbitrap can deliver these requirements and therefore provide invaluable information to forensic pathologists and Coroners to assist in their inquiries into insulin-related death investigations.
Forensic toxicology laboratories do not routinely conduct protein analyses for the likes of insulin. Therefore, this project is aimed at bridging those gaps with the development of mass-spectrometry-based proteomics for the extension of ChemCentre’s analytical capability into the analysis of ‘large’ molecules of forensic interest. An extraction method, QE Orbitrap screening and LCMS-QQQ confirmation method was developed to analyse blood and urine of insulin-related WA coronial cases. In circumstances where routine exhibits (blood/urine) are not available an alternative method for the analysis of insulin in vitreous humour was developed and validated. This study highlights an advancement in forensic technology and the promising ability of the QE Plus Orbitrap as an excellent screening tool for insulin-related forensic toxicology and proteomic investigations.