Determination of spices in food samples by ionic liquid aqueous solution extraction and ion chromatography

In the present work, a novel method to extract three kinds of spices, namely vanillin, ethyl vanillin and ethyl maltol from food products such as biscuit, chocolate and milk powder was developed. 1-Octyl-3-methylimidazolium chloride (Omim]Cl) aqueous solution was selected as the extracting medium. A 0.5 g powder of food product was extracted by 5.0 mL of Omim]Cl aqueous solution (0.3 mol/L, pH 6.0) under ultrasonication at 50 ℃, and then the extract was centrifuged for 10 min at 4000 rpm. The extract was filtered through a syringe filter and injected into ion chromatography system for analysis. The separation of the three spices was carried out on an anion exchange column. The detection wavelength was set at 280 nm. Compared with traditional extraction solvents, Omim]Cl aqueous solution displayed particular advantages. The applicability of the proposed method to real sample was confirmed. Under the optimal conditions, good reproducibility of extraction performance was obtained, with the relative standard deviation (RSD) values ranging from 1.9% to 6.3%. The recoveries of spiked samples were between 79.8% and 95.8%. The detection limits (LOD, S/N = 3) of vanillin, ethyl vanillin and ethyl maltol were in the range of 20-45 μg/kg. The use of ionic liquid aqueous solution as extraction solvent was operationally easy and environmental-friendly.