水性介质中植物油氧化诱导时间的测定

Determination of oxidation induction time of vegetable oils in aqueous medium

开发了一种绿色环保的测定植物油氧化诱导时间的体系。对流动体系的油水体积比、流量、加入铜丝长度等条件进行了优化,以不同氧化程度的橄榄油与p H 7的磷酸缓冲溶液(PBS)混合分离的水相为测量对象,以还原氧化石墨烯修饰的玻碳电极(r GO/GCE)为工作电极,利用交流阻抗法对其阻抗进行测定。结果表明:最佳油水体积比为1∶1,最适流量为1.68 m L/min,铜丝长度40cm;交流阻抗法能够灵敏地测量橄榄油自动氧化过程中产生的易溶于水的物质所引起的水相溶液阻抗的变化;交流阻抗法与国标法得到的氧化诱导时间的相对偏差小于5%,且两种方法的测定结果无显著性差异。因此,通过建立的水相体系可以准确地对植物油的氧化诱导时间进行测定。

A green and environment-friendly system for determining the oxidation induction time of vegetable oil was developed. The volume ratio of oil to water, flow rate and added copper wire length in flow system were optimized. The reduced graphene oxide modified glassy carbon electrode （rGO/GCE）was used as the working electrode, and the impedance of the aqueous phase mixed with olive oil of different oxidation degree and PBS at pH 7 was measured by AC impedance method. The results indicated that the optimal determination conditions of flow system were obtained as follows： volume ratio of oil to water 1∶1, flow rate 1.68 mL/min and added copper wire length 40 cm. The impedance changes caused by water-soluble substance of olive oil in oxidation process could be measured sensitively and rapidly by AC impedance method. The relative deviation of the oxidation induction time between AC impedance method and national standard method was less than 5%. Moreover, there was no significant difference in determination results obtained by the AC impedance method and national standard method. Therefore, the aqueous system could accurately determine the oxidation induction time of vegetable oil.