Trace Determination of Cyanide in Chinese Liquor by Coupling Automatic Distillation with the Flow Analysis Method

Cyanide, a highly toxic compound, may exist in trace amounts in distilled Chinese liquor, a traditional spirit consumed by over a billion people. To enhance the efficiency and reliability of cyanide detection, we propose a rapid, fully automated method integrating steam distillation with a continuous flow analyzer. This system combines sample pretreatment, fast distillation, and colorimetric detection using the isonicotinic-barbituric acid chromogenic system based on Lambert-Beer law (measuring at 600 nm). The standard curve exhibits an excellent linear relationship and a correlation coefficient r = 0.99959. The detection limit (0.2519 µg/L) was derived from 11 replicate blank measurements. When applied to three types of Chinese liquor, the method yields spike recovery rates ranging from 91.530% to 98.485%, and precision values between 1.177% and 1.525%. A paired t-test confirms no significant difference between this method and the national standard spectrophotometric method (t = 0.535, p = 0.615). Overall, this method offers outstanding repeatability, high accuracy, rapid analysis, and minimal manual intervention, establishing it as a reliable tool for cyanide determination and contributing to the assurance of food safety in alcoholic beverages.