顶空-气质联用法鉴别压榨植物油和浸出植物油Identification of pressed vegetable oil and extracted vegetable oil by headspace-gas chromatography-mass spectrometry

旨在为探明植物油出油方式提供技术支持，建立了一种鉴别压榨植物油和浸出植物油的方法。采用顶空-气质联用法测定植物油的残留溶剂，对顶空进样器平衡温度进行了优化，并探究植物油残留溶剂的特征性成分，通过对压榨植物油和浸出植物油样品中特征性成分的分析确定植物油出油方式的鉴别方法。结果表明：六号溶剂主要成分的出峰面积均随着平衡温度的升高而增加，优化的平衡温度为150 ℃；六号溶剂中5种主要成分在0~1.00 mg/kg范围内线性关系良好，相关系数均可达0.999以上，检出限为0.001 0~0.014 4 mg/kg；六号溶剂中不仅含有烷烃、环烷烃，还含有烯烃、芳香烃（包括多环芳烃）等，成分较为复杂，浸出植物油中溶剂残留物主要为2-甲基戊烷、3-甲基戊烷 、正己烷、甲基环戊烷和环己烷，占比达97.5%，与六号溶剂中这5种物质含量（占比达96.6%）相似，因此确定这5种物质为植物油残留溶剂的特征性成分；实际样品测定表明压榨植物油中没有溶剂残留或残留量较低，浸出植物油中均有溶剂残留且残留量较高；总结出鉴别压榨植物油和浸出植物油的方法为若同时检出4种及以上六号溶剂特征性成分或特征性成分总含量大于或等于0.50 mg/kg的样品可判定为浸出植物油，若同时检出小于或等于3种六号溶剂特征性成分且特征性成分总含量小于 0.50 mg/kg的样品可判定为压榨植物油。综上，采用顶空-气质联用法对植物油中六号溶剂的特征性成分进行分析，以特征性成分有无和含量可以鉴别压榨植物油和浸出植物油。In order to provide technical support for the exploration of vegetable oil production mode, a method for identifying pressed vegetable oil and extracted vegetable oil was established. The residual solvent in vegetable oil was determined by headspace-gas chromatography-mass spectrometry. The equilibrium temperature of headspace injection was optimized, and the characteristic components of residual solvent in vegetable oil was identified. By analyzing the characteristic components in pressed and extracted vegetable oil samples, the extraction method of vegetable oil was identified. The results showed that the peak areas of main components of No. 6 solvent increased with the increase of equilibrium temperature, and the optimal equilibrium temperature was 150 ℃. The linearity of five main components was good in the range of 0-1.00 mg/kg, the correlation coefficient was more than 0.999, and the detection limits was 0.001 0-0.014 4 mg/kg. The components of No.6 solvent were relatively complex, including not only alkane and cycloalkanes, but also olefins, aromatic hydrocarbons (including polycyclic aromatic hydrocarbons). The solvent residues in the extracted vegetable oil were mainly 2-methylpentane, 3-methylpentane, n-hexane, methylcyclopentane and cyclohexane, accounting for 97.5%, which were similar to the contents of these five substances in No. 6 solvent(accouting for 96.6%). Therefore, it was determined that these five substances were characteristic components of residual solvents in vegetable oil. The determination of practical samples showed that there was no or low solvent residue in pressed vegetable oil, while there was solvent residue in the extracted vegetable oil and the residue amount was relative high. The methods for identifying pressed vegetable oil and extracted vegetable oil were summarized as follows: if four or mor