A rapid analytical method for the determination of 45 elements in extra-virgin olive oils

The accurate determination of trace elements in edible olive oils is still an analytical challenge due to their low concentration levels and the complex matrix of vegetable oils. However, the study of possible chemical contaminants and their levels in edible olive oils is a research priority for preserving the high nutritional value and the high organoleptic quality of these products [1]. Furthermore, the analysis of trace elements plays an important role as a basis for oil adulteration detection and oil quality control. This study evaluates a new method to miniaturize the sample digestion for extra virgin olive oils by inductively coupled mass spectrometry (ICP-MS) in order to achieve accurate and reproducible results with low detection limits for the analyzed trace elements. This method has been designed to carry out the sample preparation and instrumental analysis from a single tube to prevent sample loss, minimize contamination and reduce volumes of acid and the required final dilution. To evaluate the best and fastest sample preparation procedure, ultrasonic extraction and wet digestion methods were compared using oil certified reference material with different reagent mixtures, reagent volumes, and times for sample extraction or digestion. The use of 5 mL reagent mixture consisting of 10% (v/v) HNO3 and H2O2, 2:1 (v/v) for sample digestion in a water bath (95 °C, 40 min) was found to produce satisfactory results in all cases as validated from sample recovery experiments over three different extra virgin olive oil samples [2]. This method can be used for applications such as routine analysis with high sample throughput and geographical traceability.