Source discrimination of colchicine based on carbon stable isotope analysis

Colchicine, a highly toxic alkaloid, has been frequently employed as a poisoning agent in criminal cases. Toxicant source tracing represents a critical research direction in forensic science, where the discrimination of colchicine origins holds particular significance for chemical fingerprint identification in poisoning incidents. The stable isotopic signature of colchicine serves as a crucial indicator for source comparison and traceability. However, its complexity of structure and high molecular weight present substantial challenges for precise stable isotope analysis. To enhance traceability capabilities, a method for the analysis of carbon stable isotope of colchicine was established using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Through systematic optimization of experimental conditions, we resolved incomplete oxidation issues in the combustion reactor caused by inherent chemical properties of colchicine, achieving precise measurements with a standard deviation below 0.3‰. Method validation confirmed that storage conditions and matrix effects exerted no significant impact on carbon stable isotope ratio determinations. Applied to colchicine from three distinct sources, this method demonstrated effective source discrimination through δ¹³C values. The established analytical protocol proves reliable and robust for colchicine stable carbon isotope analysis, thereby significantly increasing its traceability potential in forensic science.