Determination of vitamin E and β-sitosterol in vegetable oil wastes by graphene-based magnetic solid-phase extraction method coupled with GC-MS

The main substances of the unsaponifiable section of vegetable oils are α-tocopherol and β-sitosterol. Although the various effects of these compounds on human nutrition have been confirmed, they are still an interesting topic for research. In this research magnetic graphene oxide was made using a simple procedure and used for extraction. Moreover, it was applied as a pretreatment method before the detection of the α-tocopherol and β-sitosterol in vegetable oil wastes by Gas Chromatography-Mass Spectrometry. Several parameters such as the kind and volume of desorption solvent, the time of desorption, and the quantity of sorbent which can affect the extraction efficiency were examined. The detection limits of α-tocopherol and β-sitosterol were 0.05 mg/g and 0.01 mg/g, respectively and the quantification limits of 0.2 mg/g for both were achieved under the optimized conditions. The average recoveries of α-tocopherol and β-sitosterol were 94.44 %, 97.77 %, respectively, and Intra-day and inter-day accuracies had a relative standard deviation (RSD) of less than 2.3 and 4.8 %, respectively. The results showed that MGO could be used well to extract α-tocopherol and β-sitosterol in vegetable oil samples.