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Abstract :
[en] Since their discovery in the 1960s, aflatoxins have become a significant public health concern, presenting a formidable obstacle to ensuring food quality. Due to the carcinogenic nature of these substances and their widespread presence in various food types, regulatory authorities have established maximum allowable levels for these contaminants in such products. Traditional official methods have traditionally employed substantial quantities of methanol/water or acetonitrile/water solutions for extraction, given the slightly polar characteristics of aflatoxins. Food matrices high in lipid content, such as pistachios (constituting approximately 40% of the total lipid fraction), typically require multiple sample preparation steps before analysis. Specifically, a de-fatting step using hexane is commonly used to reduce the presence of lipid-based interferents from the matrix.
A novel approach has been developed, utilizing choline chloride–urea (molar ration 1:2) deep eutectic solvent (DES) + 20% H2O (w/w) as the extraction medium. Given the complex nature of extracts obtained from aflatoxin-contaminated pistachios, a subsequent purification and concentration step becomes crucial. The DES extracts are diluted with water and passed through a C18 solid-phase extraction cartridge. A minimal amount of methanol is used to elute the trapped aflatoxins, which are then injected into a UHPLC system coupled with a fluorescence detector. A 2-μm partially porous C18 column was employed to effectively separate aflatoxins. The mobile phase consisted of a gradient elution system using methanol and water, ranging from 30% to 60% MeOH over a period of 7.5 minutes.
The developed methodology demonstrated robustness and reliability for each analyte (CV% lower than 6.03%), with limits of quantification (LOQs) below 0.41 ng/g, without using MS detectors and/or derivatization agents.
The environmental friendliness of the developed procedure was assessed through two relevant metrics, namely, AgreePrep and WhiteChemistry – RGB, indicating superior performance compared to official methods.