A method was established for the determination of total selenium in milk powder by microwave digestion-hydride atomic fluorescence spectrometry.Using 6 mol/L hydrochloric acid for treatment,the reaction temperature was set at 80 ℃ and the reaction time was 20 minutes,with 3％(V/V)hydrochloric acid and 1.0 g/100 mL potassium borohydride as the reducing agent and carrier,the total selenium content in the milk powder containing selenium acid,selenious acid,selenocysteine,selenomethionine,and methylselenocysteine in five different forms was deter-mined.The experimental results showed that under the optimal experimental conditions,the selenium content showed good linear relationship in the range of 0-10 μg/L with the linear correlation coefficient(was)greater than 0.9998,the detection limit was 0.001 mg/kg.The selenium con-tent in milk powder of the national standard substance was determined,and the detection results were within the range of reference values.and the standard recoveries were in the range of 98.2％-109.0％at low,medium and high levels,and RSD values were in the range of 1.49％-5.29％.This method is applicable to the detection of total selenium content in milk powder containing different selenium forms.
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