The influence of nitrogen dioxide on the determination of hydrogen cyanide in mainstream and sidestream cigarette smoke and the improvement of the determination method by continuous flow analyzer

Abstract

Hydrogen cyanide is a well-known toxic component in cigarette smoke. Accurate determination of hydrogen cyanide is of great significance to assess the risk of cigarettes to public health. In the conventional method for determination of hydrogen cyanide in cigarette smoke, an alkaline solution is used to collect hydrogen cyanide. In our study, nitrogen oxides in the smoke were found to dissolve in the alkaline solution, and they could react with the alkaline solution to produce nitrates and nitrites which could further react with cyanide to result in underestimating the yield of hydrogen cyanide. An improved method for the determination of hydrogen cyanide was developed in our laboratory to solve the problem, in which the hydrogen cyanide from mainstream cigarette smoke was collected using a Cambridge filter pad (CFP) treated with an ethanol–water solution of sodium hydroxide and detected by a continuous flow analyzer based on a coloring system with isonicotinic acid and 1,3-dimethylbarbituric acid. The collection efficiency of hydrogen cyanide for this method was significantly improved compared with conventional methods of trapping hydrogen cyanide using an alkaline solution. Furthermore, the collection and sample preparation process was simpler, with higher stability of the collected hydrogen cyanide. The limit of detection (LOD) and limit of quantification (LOQ) for the determination of hydrogen cyanide were less than 1.08 × 10⁻² mg L⁻¹ and 3.74 × 10⁻² mg L⁻¹, respectively. The improved method achieved excellent recoveries in the range 99.13–100.37% for mainstream smoke detection and 96.41–101.96% for sidestream smoke detection. Excellent precision for hydrogen cyanide determination was obtained, with the intra-assay and inter-assay relative standard deviation (RSD%) for mainstream smoke detection being 3.58% and 4.44%, respectively, and the intra-assay and inter-assay RSD% for sidestream smoke detection being 1.48% and 2.28%, respectively. The method developed is reliable and suitable for routine analysis of hydrogen cyanide in both mainstream and sidestream cigarette smoke.