The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour

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dc.contributor.advisorMader, Jade
dc.contributor.advisorKhotseng, Mmitsane
dc.contributor.authorVan Vuuren, Andrew
dc.date.accessioned2026-02-02T06:50:45Z
dc.date.available2026-02-02T06:50:45Z
dc.date.issued2025
dc.date.updated2026-02-02T06:39:06Z
dc.description.abstractPost-mortem biochemistry provides valuable insights into the biochemical status of an individual at the time of death. Vitreous humour (VH) has an anatomically isolated location within the body, making it less prone to the effects of putrefaction and autolysis after death. As such, VH has frequently been described as the specimen of choice in biochemical forensic investigations to identify potential ante-mortem conditions and to estimate the post-mortem interval. The lack of a validated method for post-mortem biochemistry analysis using VH as part of routine toxicology testing within the Western Cape province of South Africa motivated the primary aim of this study, which was to develop and validate a method for the analysis of glucose, lactate, and electrolytes (potassium (K+), sodium (Na+), chloride (Cl-) and calcium (Ca2+)) using an ABL835 FLEX blood gas analyser. Method development included instrument verification and sample preparation optimisation, which assessed the effect of centrifugation and dilution. Validation included tests for accuracy, precision, sample stability, drug interferences and between-eye differences. Sample preparation experiments determined that untreated VH may be analysed directly or diluted in a 1:1 ratio with ultrapure water, when required. All analytes demonstrated acceptable bias, within-run and between-run precision at concentrations above 1.6 mmol/L. Results indicated suitable stability for K+, Na+, Cl-, glucose and lactate across all storage conditions over 31 days, while Ca2+ values decreased over time when frozen at -20°C. Drug interference was minimal for most analytes, with effects remaining within acceptable ranges (%error < ± 20%), with the exception of Ca2+. No statistically significant between-eye differences (p > 0.05) were observed for any analytes in both undiluted and diluted (1:1) samples. Overall, the method performed satisfactorily and was deemed fit for purpose for routine analysis. While important limitations regarding sample stability and potential interferences must be considered, this method provides a valuable resource for post-mortem biochemical analysis in cases of unnatural deaths in the Western Cape to support both individual case resolutions and broader public health insights.
dc.identifier.apacitationVan Vuuren, A. (2025). <i>The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour</i>. (). University of Cape Town ,Faculty of Health Sciences ,Department of Pathology. Retrieved from http://hdl.handle.net/11427/42803en_ZA
dc.identifier.chicagocitationVan Vuuren, Andrew. <i>"The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour."</i> ., University of Cape Town ,Faculty of Health Sciences ,Department of Pathology, 2025. http://hdl.handle.net/11427/42803en_ZA
dc.identifier.citationVan Vuuren, A. 2025. The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour. . University of Cape Town ,Faculty of Health Sciences ,Department of Pathology. http://hdl.handle.net/11427/42803en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Van Vuuren, Andrew AB - Post-mortem biochemistry provides valuable insights into the biochemical status of an individual at the time of death. Vitreous humour (VH) has an anatomically isolated location within the body, making it less prone to the effects of putrefaction and autolysis after death. As such, VH has frequently been described as the specimen of choice in biochemical forensic investigations to identify potential ante-mortem conditions and to estimate the post-mortem interval. The lack of a validated method for post-mortem biochemistry analysis using VH as part of routine toxicology testing within the Western Cape province of South Africa motivated the primary aim of this study, which was to develop and validate a method for the analysis of glucose, lactate, and electrolytes (potassium (K+), sodium (Na+), chloride (Cl-) and calcium (Ca2+)) using an ABL835 FLEX blood gas analyser. Method development included instrument verification and sample preparation optimisation, which assessed the effect of centrifugation and dilution. Validation included tests for accuracy, precision, sample stability, drug interferences and between-eye differences. Sample preparation experiments determined that untreated VH may be analysed directly or diluted in a 1:1 ratio with ultrapure water, when required. All analytes demonstrated acceptable bias, within-run and between-run precision at concentrations above 1.6 mmol/L. Results indicated suitable stability for K+, Na+, Cl-, glucose and lactate across all storage conditions over 31 days, while Ca2+ values decreased over time when frozen at -20°C. Drug interference was minimal for most analytes, with effects remaining within acceptable ranges (%error < ± 20%), with the exception of Ca2+. No statistically significant between-eye differences (p > 0.05) were observed for any analytes in both undiluted and diluted (1:1) samples. Overall, the method performed satisfactorily and was deemed fit for purpose for routine analysis. While important limitations regarding sample stability and potential interferences must be considered, this method provides a valuable resource for post-mortem biochemical analysis in cases of unnatural deaths in the Western Cape to support both individual case resolutions and broader public health insights. DA - 2025 DB - OpenUCT DP - University of Cape Town KW - Blood Gas Analyser KW - glucose KW - lactate KW - electrolytes LK - https://open.uct.ac.za PB - University of Cape Town PY - 2025 T1 - The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour TI - The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour UR - http://hdl.handle.net/11427/42803 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/42803
dc.identifier.vancouvercitationVan Vuuren A. The development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour. []. University of Cape Town ,Faculty of Health Sciences ,Department of Pathology, 2025 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/42803en_ZA
dc.language.isoen
dc.language.rfc3066eng
dc.publisher.departmentDepartment of Pathology
dc.publisher.facultyFaculty of Health Sciences
dc.publisher.institutionUniversity of Cape Town
dc.subjectBlood Gas Analyser
dc.subjectglucose
dc.subjectlactate
dc.subjectelectrolytes
dc.titleThe development and validation of an ABL835 FLEX Blood Gas Analyser method for the quantitation of glucose, lactate, and electrolytes in post-mortem vitreous humour
dc.typeThesis / Dissertation
dc.type.qualificationlevelMasters
dc.type.qualificationlevelMasters
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