Ideal chromatography separation and detection for determination of various anions in biological samples for forensic toxicology

The nitrogen and sulfur cycles are of growing significance in the scientific fields due to their biological processes. Both cycles have positive metabolic outcomes when in normal concentrations and conditions, however excessive intake of the inorganic anions each have fatal consequences. Concentrations of either nitrate and/or nitrite or sulfide beyond normal levels in results in toxicity, and which may result in death. Therefore, a simple, time sensitive and accurate method for the determination and quantitation of nitrite and/or nitrate and sulfide is required in the field of post-mortem toxicology, to aid in cause of death investigations. Unfortunately, several suicide cases are related to the excessive intake of nitrate and nitrite by overdose of the anions by medicine or curing salts and deaths involving car exhaust fumes also have high nitrite/nitrate levels in the deceased’s system. Due to the short half-life of nitrate in blood samples, nitrate is often required to be detected and quantitated after being converted to nitrite. With sulfide poisonings, sulfide is difficult to isolate and quantitate, so detection methods look for the metabolite thiosulfate in blood and urine samples. To the best of the authors knowledge, no recent papers have been published reviewing and comparing the methods applicable to human biological fluids since 2005. This review provides background on nitrate/nitrite and sulfide roles in biological systems, consequences of excess intake, and the current methodologies available for detection and quantitation of these anions. It was found that chromatographic methods, specifically gas chromatography mass-spectrometry and liquid chromatography mass-spectrometry, were most commonly used in forensic labs for the detection and quantitation of each anion