Determination of Hydrogen Cyanide by Gas Chromatography With Post‐Column Reaction and Flame Ionization Detection

A straightforward and practical 15-min gas chromatographic method utilizing flame ionization detection has been developed to measure hydrogen cyanide in various matrices. This new approach features a catalyzed two-stage post-column reaction that significantly enhances the detection and quantification of hydrogen cyanide. Selecting the right separation column is crucial for accurate analysis. Initial tests with porous layer open tubular columns resulted in significant peak tailing, rendering them unsuitable for trace-level analysis. Modified polyethylene glycol stationary phases also exhibited strong peak tailing in addition to producing artifact peaks. In contrast, a polydimethylsiloxane-based column with a very low phase ratio (β = 10) demonstrated excellent analytical performance, including peak symmetry and inertness. The analytical approach achieved a minimum detection limit of 50 parts per billion (ppb, v/v) without preconcentration and a linear range from 0.05 to 200 parts per million (ppm, v/v). At a concentration level of 20 ppm (v/v), the RSD at the 95% confidence level was less than 1% (n = 10), and at a concentration level of 1 ppm (v/v), the RSD at the 95% confidence level was less than 3% (n = 10) under the established conditions. The method's effectiveness has been validated through real-life applications, including analyzing hydrogen cyanide in fruit seeds and the headspace of untreated water samples.