Extraction induced by emulsion breaking for trace multi-element determination in edible vegetable oils by ICP-MS

In this study, a simple, fast and reliable method for the simultaneous ICP-MS determination of Mg, Mn, Fe, Zn, Ag, Ba, Pb and Cr in edible vegetable oils using extraction induced by emulsion breaking is proposed. In the method, each sample of oil was emulsified with a Triton X-114 solution containing HNO3 and the emulsion was broken by centrifugation for 12 min at 6800 rcf, and then the acid aqueous phase deposited in the bottom of the centrifuge tube was collected for the determination of the metals of interest. The optimization of the method was performed by studying the effect of several parameters that could affect the extraction efficiency such as the concentrations of HNO3 and the emulsifying agents (Triton X-114 and Triton X-100) in the extractant solution, the centrifugal speed and the extraction time. The limits of detection and quantification for Mg, Mn, Fe, Zn, Ag, Ba, Pb and Cr were in the range of 0.004-0.271 mu g L-1 and 0.013-0.903 mg L-1, respectively. The proposed method was applied in the determination of metals in eighty edible vegetable oil samples produced with different plants. The accuracy of the method was performed by spiking the samples with known amounts of the metals in the form of organometallic standards and the recoveries were in the range of 87-108%.