Assessing Diazinon Exposure: A GC-MS/MS Validation Study of BChE Measurement by Point-of-Care Testing and Enzyme Multiplied Immunoassay Technique

This study addresses the challenge of accurately assessing diazinon exposure in suspected self-poisoning cases. We evaluated butyrylcholinesterase (BChE) levels using a point-of-care (POCT) whole blood assay (adapted Ellman method) and compared it with the standard plasma Enzyme Multiplied Immunoassay Technique (EMIT). Diazinon exposure in four patients was confirmed using a validated gas chromatography-tandem mass spectrometry (GC-MS/MS) method with multiple reaction monitoring (MRM). A strong positive correlation was observed between POCT and EMIT BChE activity (r = 0.9638, <i>p</i> < 0.0001), indicating general agreement in BChE trends. However, Bland-Altman analysis revealed discrepancies in absolute BChE values. Notably, admission diazinon concentrations (GC-MS/MS) were significantly negatively correlated with BChE activity measured by both POCT (r = -0.9333, <i>p</i> = 0.0205) and EMIT (r = -0.9302, <i>p</i> = 0.0219). The POCT assay offers rapid, preliminary BChE assessments in suspected diazinon intoxication, useful in emergency settings. However, due to observed discrepancies, confirmatory testing with EMIT or GC-MS/MS is recommended for accurate quantification. This research highlights the critical need for robust confirmatory methods, such as GC-MS/MS, to validate rapid assays and improve the accuracy of diazinon intoxication detection.