液相色谱/四极杆-飞行时间质谱法筛查奶酪中29种禁用和限用合成色素

Screening method for 29 forbidden or limited synthetic pigmentsin cheese by liquid chromatography/quadrupole time-of-flight mass spectrometry

建立了奶酪样品中29种禁用和限用合成色素的液相色谱/四极杆-飞行时间质谱（LC/Q-TOF MS）筛查方法。样品经正己烷-水（3∶1,v/v）振荡提取,得到正己烷层、水层和残渣3部分。正己烷层经旋转蒸发浓缩后,用乙酸乙酯-环己烷（1∶1,v/v）溶解,经过凝胶渗透色谱（GPC）净化去除油脂。水层经乙腈振荡提取,得到乙腈-水提取液。残渣经氨水-甲醇（1∶99,v/v）溶液振荡提取,得到氨水-甲醇提取液。乙腈-水提取液和氨水-甲醇提取液不需净化直接分析。结果表明：29种不同极性范围的合成色素化合物分别得到了有效的提取,提取回收率为70%~95%。而Q-TOF MS提供的精确质量数定性功能可以将不同种类的合成色素化合物筛查出来,各化合物与精确质量质谱库中化合物的匹配度为59.66~99.47。通过Target MS/MS扫描方式进行定量,得到8种苏丹类化合物的方法检出限为0.4~2.5μg/kg,21种水溶性合成色素及染料化合物的检出限为20~80μg/kg。该方法对禁用和限用合成色素的筛查范围广泛,对含有蛋白质、脂肪等基质的食品具有较好的适用性。

A screening method for 29 forbidden or limited synthetic pigments in cheese samples was established by liquid chromatography/quadrupole time-of-flight mass spectrometry（LC/Q-TOF MS）.The pigments were extracted by n-hexane/water（3∶1,v/v）.After extraction,the n-hexane extract,water extract and residue,were obtained.The n-hexane extract was then cleaned-up by gel permeation chromatography（GPC）.The water extract was extracted by acetonitrile,and the residue by ammonia water/methanol（1∶99,v/v）.The results showed that the 29 synthetic pigments with a wide range of polarities were extracted effectively with the recoveries between 70% and 95%,and matched well by Q-TOF MS precision mass searching to the mass spectral library with matching scores between 59.66 and 99.47.The quantitative analysis of the 29 pigments was carried out by Target MS/MS.The limits of detection（LODs） for 8 Sudan dyes were 0.4-2.5 μg/kg while for 21 water-soluble synthetic pigments were 20-80 μg/kg.The screening method is suitable for a wide range of synthetic pigments,and can be applied to food samples with proteins and fat in matrix.