The use of immunoaffinity columns connected in tandem for selective and cost-effective mycotoxin clean-up prior to multi-mycotoxin liquid chromatographic–tandem mass spectrometric analysis in food matrices

Abstract

This paper describes the use of two immunoaffinity columns (IACs) coupled in tandem, providing selective clean-up, based on targeted mycotoxins known to co-occur in specific matrices. An IAC for aflatoxins+ochratoxin A+fumonisins (AOF) was combined with an IAC for deoxynivalenol+zearalenone+T-2/HT-2 toxins (DZT); an IAC for ochratoxin A (O) was combined with a DZT column; and an aflatoxin+ochratoxin (AO) column was combined with a DZT column. By combining pairs of columns it was demonstrated that specific clean-up can be achieved as required for different matrices. Samples of rye flour, maize, breakfast cereal and wholemeal bread were analysed for mycotoxins regulated in the EU, by spiking at levels close to EU limits for adult and infant foods. After IAC clean-up extracts were analysed by LC–MS/MS with quantification using multiple reaction monitoring. Recoveries were found to be in range from 60 to 108%, RSDs below 10% depending on the matrix and mycotoxin combination and LOQs ranged from 0.1ng/g for aflatoxin B1 to 13.0ng/g for deoxynivalenol. Surplus cereal proficiency test materials (FAPAS®) were also analysed with found levels of mycotoxins falling within the satisfactory range of concentrations (Z score≤±2), demonstrating the accuracy of the proposed multi-mycotoxin IAC methods.