Abstract:The ultrasonic-assisted extraction conditions of mineral oil in the chocolate was optimized by the response surface method in order to detect the mineral oil content in chocolate.The optimized parameters were obtained as follows：extraction time was 26 min，extraction temperature was 35℃，ratio of material to liquid was 1∶3.2 （g/mL），ultrasonic power was 120 W，respectively.Under these conditions，the extraction amount of mineral oil could reach（3.127±0.194）mg/kg，which was in agreement with the predicted value.The qualitative and quantitative analysis of mineral oil was carried out by standard curve and internal standard combination method when detected mineral oil by gas chromatography，and the linear relationship of C9-C40n-alkane standard working liquid was good in the range of 0.32 mg/L-200 mg/L.The detection limit of this method was 0.26 mg/kg and the limit of quantification was 0.78 mg/kg，respectively.The recovery rate was 85.2%～97.4% and the relative standard deviation（RSD）was between 0.37% and 1.33%，respectively.The results showed that the average content of mineral oil content in 10 kinds of chocolate sold in the market was between 1.047 mg/kg and 7.073 mg/kg.The method had accurate quantity and was simple to operate.It could be used to analyze the mineral oil content in chocolate.