Ion-Pair RP-HPLC Determination of Thiocyanate in Liquid Milk

The content of thiocyanate in liquid milk was determined by ion-pair RP-HPLC.The sample was extracted by acetonitrile,and the sample solution obtained was separated on Zorbax Extend C18 column(150 mm×4.6 mm,5 μm) with a mixture of phosphate buffer solution(containing 3 mmol·L-1 tetrabutylammonium bromide) and methanol in the ratio 70 to 30 by volume as mobile phase,and detected at 231nm by UV-detector.Linear relationship between values of peak area and mass concentration of thiocyanate was kept in the range of 0.4-50.0 mg·L-1,with detection limit(3S/N) of 0.055 mg·L-1 and lower limit of determination(10S/N) of 0.18 mg·L-1.The proposed method was applied to the analysis of liquid milk.Tests for recovery and precision were made by standard addition method,giving values of recovery and RSD′s(n=6) in the ranges of 92.0%-102% and 2.53%-4.86% respectively.