Vesicular aggregate-based solventless microextraction of Ochratoxin A in dried vine fruits prior to liquid chromatography and fluorescence detection

A solventless microextraction was proposed for the development of a simple, fast, low-cost and environmental friendly sample treatment for the determination of Ochratoxin A (OTA) in dried vine fruits. The objective was to offer an alternative to conventional sample treatments, which invariably involve extractions with large solvent volumes followed by clean-up with expensive, not recyclable and limited storage stability immunoaffinity sorbents. The method involved the stirring of 300 mg of dried vine fruit subsamples with 400 μL of a supramolecular solvent (SUPRAS) made up of decanoico acid/tetrabutylammonium decanoate vesicles. Then, the sample was centrifuged for 15 min and OTA was quantified in the extract by liquid chromatography/fluorescence detection against solvent-based calibration curves. Neither dilution nor further clean-up steps of extracts were needed. Quantitation of OTA was interference-free and recoveries ranged between 95% and 101%. The precision of the method, expressed as relative standard deviation (RSD), was about 3%. The limit of quantification (5.3 μg kg−1) was below the threshold limit established for OTA in dried vine fruits by EU directives (10 μg kg−1). Representativity of subsamples was proven. The method was successfully applied to the analysis of several dried vine fruits (sultanas and muscatels) purchased in local supermarkets in Córdoba (South of Spain). OTA was not detected in any of the analyzed samples. This solventless sample treatment allows quick and simple microextraction of OTA, while delivering accurate and precise data, and extends the range of eco-friendly methods in labs.