The identification and quantification of toxic contaminants in essential oils is of primary concern especially when they are used in food, pharmaceutical and cosmetic products. Among the toxicant to be assessed, pesticides are of primary importance, due to their wide use on the crops and their high chemical affinity with the essential oils constituents.
From the analytical standpoint, Essential Oils are complex matrices and pesticides determination can be challenging. For this reason a previous extraction and clean up are usually required to separate pesticides from the Essential Oil components before the analysis. However, due to the chemical affinity of pesticides and Essential Oils constituents, the purification is not often satisfactory and pesticides are most likely co-extracted with essential oils components having similar polarities and volatility. A direct injection of the sample would be therefore desirable, with the additional benefit to avoid time consuming and costly sample clean-up procedures.
When direct injection is considered, the complexity of the matrix can be much better handled by exploiting the separation capability of the GCxGC-TOF-MS approach, with enhanced separation of the target compounds from the matrix, reduced matrix effect for lower LOD and cleaner MS spectra for reliable identification.