Abstract:Sodium thiocyanate (NaSCN), a chemical raw material with preservative effect, was often used in dairy products to extend the shelf life, which increased the safety risk. The rapid detection methods for sodium thiocyanate that had been reported had several drawbacks such as serious background interference and low sensitivity. A NaSCN semi-quantitative rapid detection method was established in this study with the principle of sanguineous complex reaction induced by SCN- and Fe3+ by selecting the chromogenic agent, optimizing chromogenic reaction conditions, simulating milk matrix, pretreating samples and the chromogenic reaction. The rapid determination kit for sodium thiocyanate residues in liquid milk samples was developed. The optimum conditions were as follows: the chromogenic agent, 2 mol/L iron nitrate (2 mol/L nitric acid as the solvent); reaction time, 2 min. The reaction was complete in room temperature under the optimum conditions. The detection limit of the kit for sodium thiocyanate residues in liquid milk was 5 mg/kg, and the color gradient was well distinguished in the NaSCN concentration of 5~100 mg/kg. The proposed kit was accurate, sensitive, rapid (5 min), stable and not in need of instrument assistance, and wad suitable for on-site screening a large quantities of liquid milk samples for small and medium-sized enterprises and basic units.
