A Screening Method for Cyanide in Blood by Dimethoxytriazinyl Derivatization-GC/MS

A simple screening analysis of cyanide in blood has been developed, using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM). DMTMM, a convenient reagent for dehydrocondensation, converted cyanide to 2-cyano-4,6-dimethoxy-1,3,5-triazine, the dimethoxytriazinyl derivative of cyanide. This reaction proceeded in whole blood samples after treatment with trichloroacetic acid, and in basic aqueous solution samples. Sufficient sensitivity was observed by the method using gas chromatography/mass spectrometry. Intra- and inter-day repeated analyses (0.05, 0.1, 0.25, 1 and 5 μg/mL, n = 5) were performed and the accuracy and precision were within 20% for the lower limit of quantification (LLOQ) and within 15% for other concentrations. LLOQs for the aqueous solution and blood were 0.05 and 0.1 μg/mL, respectively, which are suitable for detecting cyanide poisoning. The limits of detection (signal-to-noise ratio ≥ 3) for aqueous solution and blood were 0.01 and 0.05 μg/mL, respectively. Interference from 13 other anions was tested and no false positive response was obtained, even in the case of thiocyanate, nitrite and nitrate, which are known to yield cyanide by acid treatment of blood. This method is practical because it uses readily available reagents and equipment and is sensitive enough for the rapid screening of cyanide poisoning in forensic and clinical toxicology.