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

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 mu L of water, then 5 mu L 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 NaAuCl(4) to produce dicyanogold, Au(CN) (2) (-) , that was extracted with 75 mu L 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 mu g/L with the limit of detection at 0.56 mu g/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 mu g/L for six healthy non-smokers, 3.08 +/- 1.12 mu g/L for six CO gas victims, 730 +/- 867 mu g for 21 house fire victims, and 3,030 +/- 97 mu g/L for a victim who ingested NaCN. The increase of CN(-) in the blood of a victim who ingested NaN(3) 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 mu g/L, respectively.