Abstract: Objective:To establish the reversed-phase ultra performance liquid chromatography(UPLC) with internal standard method for detecting the serum vitamin A level of children,in order to understand the school-age children vitamin A nutritional status,and provide reference in formulating the dietary nutrition plan.Methods:The 100 μl standard was added to the 100 ml serum of school aged children in Fuyang city Yingshang county,which was oscillated,mixed,extracted using 1.0 ml of hexane extraction and centrifugated.The supernatant was dried with N₂,redissoluting using 200 μl of anhydrous ethanol,and which was determined by UPLC.The chromatographic column was the chromatographic conditions,which included Waters C18 column(2.1 mm×100 mm,1.7 μm),secondary array detector;mobile phase,acetonitrile:water(96:4) prodegassing before using.The detection wavelength was 325 nm,the column temperature was 40 ℃,the flow rate was 0.3 ml/min and the adding sample was 2 μl.Results:The serum vitamin A concentration in 360 school-age children was 0.072 8 to 0.728 μg/ml,the range of which showed a good linear relationship(r>0.999).The mean value of vitamin A was 39.6 μg/dl,CV was less than 5%.The lowest detection limit of vitamin A was 0.020 μg/ml,which could be detected within 4.0 min.Among 360 school aged children,the children with vitamin A level equal to or less than 20 μg/dl,equal to 30 μg/dl and more than or equal to 30 μg/dl were accounted for 1.11%,19.17% and 79.72%,respectively.Conclusions:The overall survey results meet the requirements of dietary nutrition plan.The reversed-phase ultra performance liquid chromatography with internal standard method in detecting the serum vitamin A level of children is fast,sensitive,accurate and reproducible.