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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。
Objective To establish a new detection method based on gas chromatography-mass spectrometry (GC-MS) to determine the residual constituents of 25 kinds of mineral oil in milk powder and chocolate. Methods The sample was extracted with n-hexane, and the extract was purified by silica gel SPE column. After the sample was concentrated and fixed, the sample was reconstituted for analysis. The Agilent DB-5MS capillary column (30 μm × 0.25 mm, 1 μm) (selective ion mode, SIM) model, external standard quantitative analysis. Results The results showed that the response of 25 kinds of index components was inconsistent on the mass spectrometry. However, the correlation coefficients were all above 0.990 in the range of their concentration. The detection limit of milk powder (0.025-1.5 mg / kg) was higher than that of chocolate Detection limit (0.005 ~ 1 mg / kg). The spiked recoveries ranged from 25% to 56%, and the relative standard deviations (RSDs) ranged from 2.2% to 9.4%. The tests of mineral oil in 40 batches of milk powder and 25 batches of chocolate products at home and abroad showed that the detection rate of milk powder was 12.5% and the detection rate of chocolate was 100%. Conclusion The method pretreatment is simple, the analysis time is short and the 25 kinds of contaminants can be well separated, which can be used as a rapid detection method of mineral oil.