Modified congener analysis: Quantification of cyanide in whole blood, other body fluids, and diverse beverages

The congener analysis is routinely used for the determination of volatile compounds in body fluids and beverages for forensic investigations. Although intoxications with cyanide via smoke inhalation or ingestion of cyanide salts are frequently encountered in forensic medicine, the inclusion of hydrogen cyanide in this analysis was never studied in detail. In this work, a very simple, fast, and sensitive quantification method with headspace gas chromatography and flame ionization detection for the analysis of cyanide in whole blood-was developed and validated. In contrast to the standard sample preparation of the congener analysis, an acidification step with tartaric acid was added. A limit of detection of 50 ng/ml, good linearity (coefficient of correlation > 0.9997), high accuracy (101.5%-106.4%), and precision (relative standard deviation 1.8%-3.7%) were achieved. Authentic blood samples of 10 forensic cases were investigated with the new method. Furthermore, the method was used for the quantification of cyanide in other body fluids (serum and urine) and diverse beverages. Interferences were investigated, and the addition of aldehydes produced a clear concentration-dependent decrease of the cyanide signal. Besides, the method offers an economical use of limited sample material by the simultaneous determination of cyanide, ethanol, and congener alcohols.