Objective To establish a new method for determination of 25 kinds of marker substances of mineral oil in milk powder and chocolate by gas chromatography-mass spectrometry (GC-MS).Methods Samples were fully extracted by hexane,extracting solution was cleaned up by silica solid phase extraction (SPE) column,and then concentrated to certain volume by hexane.The analysis was performed on an Agilent DB-5MS capillary column (30 m×0.25 mm,1 μm),and the selective ion mode (SIM) mode and the external standard method were used for quantitative analysis.Results The responses of 25 kinds of indicators were inconsistent on the MS,but it was all well within its linear range,and the correlation coefficients (r) were above 0.990.The limit of detection of milk powder was commonly higher than chocolate,which were 0.025～1.5 mg/kg and 0.005～1 mg/kg,respectively.The recoveries of spiked samples ranged from 25％～55％,with RSD of 2.2％～9.4％.This method was verified with 40 milk powder products and 25 chocolate products,the inspection rates were 12.5％ and 100％,respectively.Conclusions This method is simple and has a short analysis time and good separation of 25 kinds of pollutants,which can be used as a quick detection method for mineral oil.%目的 建立基于普通气相色谱串联质谱(gas chromatography-mass spectrometry,GC-MS)的新检测方法确定乳粉和巧克力中25种矿物油残留成分.方法 样品经正己烷提取,提取液经过硅胶固相萃取柱净化,浓缩定容后复溶待测,选取安捷伦DB-5MS毛细管柱(30 m×0.25 mm,1μm)为分析住,采用选择离子扫描(selective ion mode,SIM)模式,外标法定量分析.结果 25种指标成分在质谱上响应程度不一致,但在各自的浓度范围内线性关系良好,相关系数r均在0.990以上,乳粉的检出限(0.025～1.5 mg/kg)均高于巧克力的检出限(0.005～1 mg/kg).加标回收率在25％～56％之间,相对标准偏差(relative standard deviation,RSD)在2.2％～9.4％之间.对国内外40批乳粉和25批巧克力产品中的矿物油进行检测,结果发现乳粉的检出率为12.5％,巧克力的检出率为100％.结论 该方法前处理操作简单,分析时间短且能良好的分离25种污染成分,可作为矿物油快速检测方法.
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