A simple extraction method with no lipid removal for the determination of aflatoxins in almonds by liquid chromatography tandem-mass spectrometry (LC-MS/MS)

The present study describes a simple and rapid method for the determination of aflatoxins in almonds using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Aflatoxins were extracted using a modified QuEChERS method with little sample preparation, excluding the use of laborious purification procedures. Extracts were frozen overnight to separate the majority of lipids. The method was successfully validated for almonds. Linearity was demonstrated in the range 0.125-20 µg/kg. Limits of quantification (LOQ) ranged from 0.34 to 0.5 μg/kg. Matrix effect was not significant for the aflatoxins. Satisfactory recoveries were obtained at spike levels below 1 μg/kg and between 1 and 10 μg/kg. Relative standard deviations (RSDs) of repeatability and reproducibility were below 15%. The method was successfully tested with two proficiency tests in almond powder and peanut paste, with acceptable z-scores (-2 ≤ z ≤ 2). Only one of 11 local almond samples contained detectable aflatoxins, at concentrations below the maximum permitted level.