Determination of 3-mercaptopyruvate in Plasma by High Performance Liquid Chromatography Tandem Mass Spectrometry

Accidental or intentional cyanide poisoning is a serious health risk. The current suite of FDA approved antidotes, including hydroxocobalamin, sodium nitrite, and sodium thiosulfate is effective, but each antidote has specific major limitations, such as large effective dosage or delayed onset of action. Therefore, next generation cyanide antidotes are being investigated to mitigate these limitations. One such antidote, 3-mercaptopyruvate (3-MP), detoxifies cyanide by acting as a sulfur donor to convert cyanide into thiocyanate, a relatively nontoxic cyanide metabolite. An analytical method capable of detecting 3-MP in biological fluids is essential for the development of 3-MP as a potential antidote. Therefore, a high performance liquid chromatography tandem mass spectrometry (HPLC-MS-MS) method was established to analyze 3-MP from rabbit plasma. Sample preparation consisted of spiking the plasma with an internal standard (13C3-3-MP), precipitation of plasma proteins, and reaction with monobromobimane to inhibit the characteristic dimerization of 3-MP. The method produced a limit of detection of 0.1 μM, a linear dynamic range of 0.5–100 μM, along with excellent linearity (R2 ≥ 0.999), accuracy (±9% of the nominal concentration) and precision (\u3c7% relative standard deviation). The optimized HPLC-MS-MS method was capable of detecting 3-MP in rabbits that were administered sulfanegen, a prodrug of 3-MP, following cyanide exposure. Considering the excellent performance of this method, it will be utilized for further investigations of this promising cyanide antidote

Comparison of Cyanide Exposure Markers in the Biofluids of Smokers and Non-smokers

Cyanide is highly toxic and is present in many foods, combustion products (e.g. cigarette smoke), industrial processes, and has been used as a terrorist weapon. In this study, cyanide and its major metabolites, thiocyanate and 2-amino-2-thiazoline-4-carboxylic acid (ATCA), were analyzed from various human biofluids of smokers (low-level chronic cyanide exposure group) and non-smokers to gain insight into the relationship of these biomarkers to cyanide exposure. The concentrations of each biomarker tested were elevated for smokers in each biofluid. Significant differences (p \u3c 0.05) were found for thiocyanate in plasma and urine, and ATCA showed significant differences in plasma and saliva. Additionally, biomarker concentration ratios, correlations between markers of cyanide exposure, and other statistical methods were performed to better understand the relationship between cyanide and its metabolites. Of the markers studied, the results indicate plasma ATCA, in particular, showed excellent promise as a biomarker for chronic low-level cyanide exposure