Determination of mycotoxins in nuts by ultra high-performance liquid chromatography-tandem mass spectrometry: Looking for a representative matrix

Abstract

A method was developed for the determination of 6 mycotoxins (α-zearalenol and zearalenone, and aflatoxins B1, B2, G1 and G2) in nuts. For that purpose, a QuEChERS based method (quick, easy, cheap, effective, rugged and safe) procedure has been used as well as ultra-high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS). Peanuts was selected as representative matrix after checking several matrices (almonds, hazelnuts, peanuts, pistachios and walnuts). Thus, a quantification strategy of mycotoxins in nuts has been stablished using only one matrix.The method was also fully validated and the quantification limit was set at 0.5 μg kg−1 for the four aflatoxins and 1 μg kg−1 for α-zearalenol and zearalenone. Appropriate recoveries were obtained at low concentration levels (0.5, 10 and 25 μg kg−1), ranging from 80 to 120%. Intra and inter-day precision values, expressed as relative standard deviation, were lower than 20%. Expanded uncertainty was also estimated and it was below 42%.To check the applicability of the method, it has been applied to 36 samples of different types of nuts, such as almonds, hazelnuts, peanuts, pistachios and walnuts. Aflatoxin G2 was detected in 40% of the analysed samples at concentrations up to 6.3 μg kg−1.