Determination of cyanide in blood by electrospray ionization tandem mass spectrometry after direct injection of dicyanogold

摘要

An electrospray ionization tandem mass spectrometric (ESI-MS-MS) method has been developed for the determination of cyanide (CN–) in blood. Five microliters of blood was hemolyzed with 50 μL of water, then 5 μL of 1 M tetramethylammonium hydroxide solution was added to raise the pH of the hemolysate and to liberate CN– from methemoglobin. CN– was then reacted with NaAuCl₄ to produce dicyanogold, Au(CN)₂–, that was extracted with 75 μL of methyl isobutyl ketone. Ten microliters of the extract was injected directly into an ESI-MS-MS instrument and quantification of CN– was performed by selected reaction monitoring of the product ion CN– at m/z 26, derived from the precursor ion Au(CN)₂– at m/z 249. CN– could be measured in the quantification range of 2.60 to 260 μg/L with the limit of detection at 0.56 μg/L in blood. This method was applied to the analysis of clinical samples and the concentrations of CN– in the blood were as follows: 7.13 ± 2.41 μg/L for six healthy non-smokers, 3.08 ± 1.12 μg/L for six CO gas victims, 730 ± 867 μg for 21 house fire victims, and 3,030 ± 97 μg/L for a victim who ingested NaCN. The increase of CN– in the blood of a victim who ingested NaN₃ was confirmed using MS-MS for the first time, and the concentrations of CN– in the blood, gastric content and urine were 78.5 ± 5.5, 11.8 ± 0.5, and 11.4 ± 0.8 μg/L, respectively.