Determination of eight anions in liquid milk

Abstract

Objective： A rapid method was established for the simultaneous determination of variety anions in liquid milk. Methods： The macromolecular protein in liquid milk was precipitated by acetonitrile, and a variety of anions were extracted. After purification by C18 column, the material was separated by Dionex IonPac AS19-HC ion column with gradient elution of potassium hydroxide and conductivity detection. Finally, a method for the determination of bromate, thiocyanate, nitrite, nitrate, chlorate, perchlorate, phosphate and iodine ion in liquid milk was established using ion chromatograph. Results： The results showed that the correlation coefficients （R2）of eight kinds of anion range from 0.999 0 to 0.999 8 in the linear range, and the limits of detection were between 0.065 mg/kg and 0.417 mg/kg. The recoveries were in the range 81.8%~102.0% with the relative standard deviations in the range 1.1%~6.7%（n=6）. Conclusion： The method has the advantages of simple operation, high accuracy and sensitivity, and can be used for simultaneous determination of various anion residues in liquid milk.

Keywords

• liquid milk
• ion chromatography
• conductivity detection
• anionic