To a greener way in aflatoxins determination: a deep eutectic solvent–based approach

Since their discovery in the 60’ aflatoxins have posed a serious issue on public health and a challenging target for food quality control. Indeed, their carcinogenic potential and their presence in different food matrices such as nuts, maize, rice and dairy products, lead authorities to set maximum levels of these contaminants in the aforementioned goods. Due to the slightly polar nature of these compounds, official methods are based on the use of methanol/water or acetonitrile/water solutions as extraction media. Also, since the contamination is inhomogeneous among the batch the analysis needs a substantial quantity of sample and extraction solvent, resulting in process waste. Here, a new method is proposed based on deep eutectic solvents (DES) as extraction media. DES are a new class of green solvents based on coupling a hydrogen bonding donor and a hydrogen bonding acceptor in an appropriate molar ratio, resulting in a clear solution with a melting point far lower than the constituents themselves. Most DESs already showed not toxic and biodegradable properties with good extraction power for several target compounds. Due to the complex nature of the extract, obtained by aflatoxin-contaminated pistachios, a further clean-up and concentration step was mandatory. DES extracts were diluted with water and passed throughout an SPE C18 cartridge, the trapped aflatoxins were then eluted with a minimum quantity of methanol and injected on HPLD-FLD for chromatographic separation, detection and quantification. This approach showed the feasibility of DES as extraction media for such a complex matrix, reducing the use of typical solvents and process waste.