A procedure for the determination of HCN in cigarette smoke is described which enables relatively large numbers of cigarettes to be smoked per sample. A multiple-port smoking machine is utilized and the HCN is trapped from whole smoke by Ascarite contained in a small glass tube mounted immediately behind the cigarette. This method of trapping was found to circumvent losses of HCN on Cambridge pads normally used for separation of particulate and gas phases of smoke. Five cigarettes are smoked through each trap. After smoking, the Ascarite is extracted with water and the extract analyzed for cyanide by a colorimetric pyridine-pyrazolone procedure which has been automated through use of a Technicon AutoAnalyzer. This procedure employs the reaction of cyanide with Chloramine-T in a buffered solution to form cyanogen chloride which in turn reacts with pyridine and pyrazolone to form a colored product. The method has been applied to various types of cigarettes with typical values in micrograms of HCN per puff for unfiltered smoke of 28 to 39; for cellulose acetate filtered smoke, 24 to 30; and for carbon + cellulose acetate filtered smoke, 14. The standard deviation for a pot of 5 cigarettes usually ranges from 1 to 3 micrograms of HCN per puff with a sample obtained from a single carton. The colorimetric procedure as described detects HCN free or combined as cyanohydrin.

(Full article published with kind permission from "Tobacco International")