Abstract: A method for the determination of thiocyanate in dairy products by headspace gas chromatography was established. At first, the thiocyanate in dairy products was extracted by water. Then, the zinc acetate solution was added to the crude product for protein precipitation. The extract obtained above was centrifuged and the supernatant was added with chloramine T, which derivatized the thiocyanate ions to cyanogen chloride. The head-space vapor of the final extract was injected into a BP10 (14% cyanopropyl phenyl polysiloxane) gas chromatographic column, and detected by an electron capture detector (ECD). The target compound was quantified by external standard. The results showed that there was a good linearity between 0.005 mg/L and 0.1 mg/L with the correlation coefficient (r) of 0.997, and the limit of detection (signal-to-noise ratio(S/N) ≥10)was 0.1 mg/kg. The recoveries were 90.0%~110.0% with the relative standard deviations (RSDs) (n=10) of 4.98%~7.89% at the three spiked levels of 1.0, 2.0, 10.0 mg/kg. In conclusion, this method is simple, rapid and accurate. It can be applied in the determination of thiocyanate in dairy products, and meets the requirements of the daily testing. The method has been successfully used to test 18 kinds of commercially available dairy products and it was found that all the dairy products tested contained thiocyanate about 0.5~10 mg/kg.

Key words: dairy products, thiocyanate, headspace gas chromatography