Determination of Cyanide in Blood by Isotope-Dilution Gas Chromatography-Mass Spectrometry

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 52; no. 3; pp. 458 - 467
• Main Authors: Murphy, Karen E, Schantz, Michele M, Butler, Therese A, Benner, Bruce A., Jr, Wood, Laura J, Turk, Gregory C
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.03.2006; American Association for Clinical Chemistry; Oxford University Press
• Subjects: Analytical, structural and metabolic biochemistry; Ascorbic Acid; Biological and medical sciences; Blood; Carbon Radioisotopes; Cyanides - blood; Fundamental and applied biological sciences. Psychology; Gas chromatography; Gas Chromatography-Mass Spectrometry; Humans; Hydrogen Cyanide - blood; Indicator Dilution Techniques; Indicators and Reagents; Investigative techniques, diagnostic techniques (general aspects); Mass spectrometry; Medical sciences; Nitrogen Isotopes; Temperature; Toxins; Uncertainty; Gas chromatography; Blood gas; Clinical biology; Isotope dilution; Biochemistry; Cyanides; Molecular biology; Mass spectrometry
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1373/clinchem.2005.061002

Cyanide (CN) is a lethal toxin. Quantification in blood is necessary to indicate exposure from many sources, including food, combustion byproducts, and terrorist activity. We describe an automated procedure based on isotope-dilution gas chromatography-mass spectrometry (ID GC/MS) for the accurate and rapid determination of CN in whole blood. A known amount of isotopically labeled potassium cyanide (K13C15N) was added to 0.5 g of whole blood in a headspace vial. Hydrogen cyanide was generated through the addition of phosphoric acid, and after a 5-min incubation, 0.5 mL of the headspace was injected into the GC/MS at an oven temperature of -15 degrees C. The peak areas from the sample, 1H12C14N+, at m/z 27, and the internal standard, 1H13C15N+, at m/z 29, were measured, and the CN concentration was quantified by ID. The analysis time was 15 min for a single injection. We demonstrated method accuracy by measuring the CN content of unfrozen whole blood samples fortified with a known amount of CN. Intermediate precision was demonstrated by periodic analyses over a 14-month span. Relative expanded uncertainties based on a 95% level of confidence with a coverage factor of 2 at CN concentrations of 0.06, 0.6, and 1.5 microg/g were 8.3%, 5.4%, and 5.3%, respectively. The mean deviation from the known value for all concentrations was <4%. The automated ID GC/MS method can accurately and rapidly quantify nanogram per gram to microgram per gram concentrations of CN in blood.