冷冻结晶-高效液相色谱法定量分析 食用油中4种生育酚Quantitative analysis of four tocopherols in edible oils by freezing crystallization-high performance liquid chromatography method

为提高生育酚的检测效率，建立了一种冷冻结晶-高效液相色谱（HPLC）法对食用油中4种生育酚(α-、β-、γ-、δ-生育酚)进行定量分析的方法，并将该方法用于玉米油、花生油和特级初榨橄榄油等食用油中生育酚的定量测定。结果表明：优化的方法为将1.0 g油样充分溶解于40 mL甲醇-乙酸乙酯-乙醇（体积比5∶ 3∶ 2）混合溶剂中，然后在-18 ℃下低温冷冻24 h，抽滤、减压蒸干、复溶后上机检测，HPLC采用C30色谱柱，以乙醇-异丙醇（体积比8∶ 1）和水为流动相进行等度洗脱，采用外标法定量；4种生育酚在2~100 μg/mL质量浓度范围内线性关系良好，检出限最低为0.179 μg/mL，定量限最低为0.59 μg/mL，方法的日内和日间精密度相对标准偏差（RSD）分别为0.57%~4.98%和1.67%~4.34%，加标回收率为96.57%~109.14%。综上，冷冻结晶-高效液相色谱法具有操作简便、提取效率高、结果准确性好等特点，适用于食用油中生育酚的定量检测。 In order to improve the detection efficiency of tocopherols, a method of freezing crystallization-high performance liquid chromatography (HPLC) for the quantitative analysis of four tocopherols, α-, β-, γ- and δ-tocopherols in edible oils was developed, and the method was applied to the quantitative determination of tocopherols in edible oils such as corn oil, peanut oil, and extra virgin olive oil. The results showed that the optimal method was that 1.0 g oils were fully dissolved in 40 mL solvent mixture of methanol-ethyl acetate-ethanol (volume ratio of 5∶ 3∶ 2), and then frozen at -18 ℃ for 24 h. The samples were extracted, filtered, evaporated under vacuum and re-dissolved and then detected. The HPLC was carried out on a C30 column, with the mobile phases of ethanol-isopropanol (volume ratio of 8∶ 1) and water for isocratic elution. The samples were quantified by the external standard method. The linearity of the four tocopherols was good in the mass concentration range of 2-100 μg/mL, the lowest limit of detection was 0.179 μg/mL, and the lowest quantitative limit was 0.59 μg/mL. The relative standard deviations (RSD) of the intra-day and inter-day precision of the method ranged from 0.57% to 4.98% and 1.67% to 4.34%, and the spiked recoveries ranged from 96.57% to 109.14%, respectively. In conclusion, the freezing crystallization-HPLC method is suitable for the quantitative determination of tocopherols in edible oils because of its easy operation, high extraction efficiency and good accuracy.