PREPARATION OF A SIMPLE SYSTEM FOR THE AN ALYSIS OF CYANIDE USING A HYDROCYANIDE GAS SENSOR AND APPLICATION TO THE ANALYSIS OF BLOOD-SAMPLES

A simple system for the potentiometric measurement of cyanide in blood samples has been developed for forensic poisoning in fire accidents b ased on a HCN gas sensor with a gaspermeable PTFE diaphragm. HCN gas p roduced from a sample (1 ml) containing cyanide was measured by adding 1 ml of 50% phosphoric acid in a 25 mi sealed Teflon vessel. Although the presence of sulfide in the sample interfered significantly with t he measurements, no influence was observed by CO in the present system . The analytical results for blood samples obtained by the present mea suring system were in excellent agreement (r=0.998) with those obtaine d by gas chromatography, which has been the conventional method used s o far. The proposed method is very much advantageous and useful for ra pid field analyses of cyanide in blood samples, for example to clarify the cause of death at the location of a fire due to the following rea sons. No contamination by the blood sample takes place, because the se nsor is placed in the gas phase and the blood sample does not touch th e sensor at all; thus, many repetitive measurements are possible with high reliability and reproducibility; the system is simple enough to b e portable to any place; it is safe in operation for measurement; it p rovides a rapid analysis etc.