The operation details of the first internal standard method of GB 5009.168-2016"Determination of Fatty Acids in Food under the National Standard for Food Safety"were improved,and the analytical method for the detection of docosa-hexaenoicacid(DHA)in dairy products was established.The improved method is to hydrolyze and extract the fat in the Maurer bottle,which reduces the use of traditional heating reflux device and liquid separation funnel.In addition,the flow rate of nitrogen,hydrogen and air in the instrument conditions is adjusted to 25,30 and 400 mL/min,the initial temperature is adjusted to 100℃ in the heating program,and the heating rate is adjusted.The results showed that DHA standard solu-tion showed a good linear relationship in the concentration of 10-2 000 μg/mL,the correlation coefficient R2 was 0.999 4,the detection limit of the method was 0.03 mg/100 g,and the quantification was 1.3 mg/100 g.The samples were added with low,medium and high concentrations of DHA.The recoveries were in the range of 87.3％-105.9％,and the relative standard deviations(RSD)were in the range of 3.65％-4.80％.DHA in the quality control sample of infant formula milk powder was determined,and the results were all within the labeled range.The improved method is simple,rapid and accurate,and is suitable for the detection of DHA in dairy products in large quantities.
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