Abstract:

A high performance ion chromatographic (HPIC) method was developed for determining thiocyanate in fresh milk. Samples were added with 3.0% acetic acid aqueous solution to precipitate protein and filtrated. The filtrate obtained was cleaned up using Dionex OnGuard RP cartridge for the removal of lipids prior to chromatographic separation. The elutant was adjusted to contain 60 mmol/L hydroxyl ions. The external standard method was used for thiocyanate quantification. Stability experiments gave an average retention time and an average peak area of 5 injection replicates of thiocyanate of 15.445 min and 0.1839 μS·min, with RSDs of 0.12% and 0.26%, respectively. Spike recoveries of thiocyanate in milk power and fresh milk at two levels ranged from 96.0% to 98.0%, with RSDs of less than 1.06%. The method exhibited a limit of detection of 0.2 mg/kg and a linear range of 0.5 to 6 mg/L.

Key words: fresh milk, thiocyanate, high performance ion chromatography (HPIC)