Determination of cyanide, in urine and gastric content, by electrospray ionization tandem mass spectrometry after direct flow injection of dicyanogold

A rapid and sensitive electrospray ionization tandem mass spectrometric (ESI–MS–MS) procedure was developed for the determination of cyanide (CN−). CN− in biological fluids was reacted with NaAuCl4 to produce dicyanogold, Au(CN)2−, which was extracted with methyl isobutyl ketone (MIBK). One microliter of the extract was injected directly into an ESI–MS–MS instrument. Quantification of CN− was performed by selected reaction monitoring of the product ion CN− at m/z 26 that derived from precursor ion Au(CN)2− at m/z 249. CN− could be measured in the quantification range of 10−7 to 5 × 10−5 M with the limit of detection at 4 × 10−8 M using 10 μL of urine within 10 min. A victim's urine and gastric content were diluted with water to 4-fold and 500-fold and measured, respectively.