The Development Of Milk Powder Reference Material For Food Safety Analysis

In order to alleviate the situation in urgent need of dairy product reference materials in China, combined with the limited content of contaminants in national food safety standards, especiallyAl, Cr, Cu, Se, Ni, Cd, Hg, Pb, nitrite, nitrate and other contaminants in milk powder, I developed a series of milk powder reference materials, which will be used for food safety analysis.We used infant formula milk powder, skim milk powder, whole milk powder as matrix. A series of reference materials were made from some special process, which contains adding target elements, spray drying and vacuum freeze drying. After that, the products were packed in a clean, dry environment. The method of deterring value for series of reference materials was taking into account several labs with different principles.(1) The main content as followed:The infant milk powder reference materials contain 9 kinds of heavy metals were prepared by spray drying. The optimized parameters affecting product quality are as follows inlet temperature:160℃, high pressure gas flow rate:25m3/h, concentration: 20%. The water content is about 1.3%, and the nutrition index content have not changed.Milk powder reference materials contain Nitrite and nitrate are prepared by vacuum freeze drying. When the concentration on more than 30%, the thickness of the sample is 15 mm, the water production is less than 3.5%, and have good uniformity.(2)The heavy metals content were determined by microwave digestion -ICP-MS and IDMS. Evaluate the homogeneity and stability of reference material. Determining the Al、Cr、Cu、Se、Ni、Cd、Hg、Pb value in reference material, we took into account several labs’ date with different principles.The milk powder was measured for nitrate and nitrite contents in the samples by using acetic acid protein precipitation-solid extraction-ion chromatography method. Another method is Dialysis-Ion Chromatography with ultra violet detector. Evaluate the homogeneity and stability of reference material which contain nitrate and nitrite.In this work, we developed a series of milk powder reference material, verified detection methods, eventually determined the characteristic value in reference material.