Validation d'une méthode de routine pour le dosage des cyanures sanguins par HS-GC/MS : application à un décès après exposition à du fumier

Cyanide is a rapid acting poison, chemically represented by 1 atom of carbon bound to 3 atoms of nitrogen CN−. Salts of cyanide are highly toxic, as it is the case for its acid, cyanhydric acid. Cyanides belong to the mandatory poisons that are requested by the French justice in case of a complete toxicological expertise. We have developed a rapid and sensitive procedure using headspace gas chromatography coupled to mass spectrometry (HS-GC/MS). After acid release in presence of acetonitrile used as internal standard, cyanides are separated on a non-polar standard capillary column HP Wax (30 m × 0.25 mm ID, 0.25 μm), then detected and quantified by mass spectrometry (m/z 27, 26). The limit of quantitation of the procedure is 75 ng/mL, which is enough for routine testing. The method was validated using the ISO17025 standards. The case of a victim deceased after manure exposure is presented. The blood cyanide concentration was 1398 ng/mL, which can be interpreted as potentially fatal. Factors that can interfere with the interpretation of post-mortem cyanide interpretation are discussed.