Comparison of nanofibers, microfibers, nano/microfiber graphene doped composites, molecularly imprinted polymers, and restricted access materials for on-line extraction and chromatographic determination of citrinin, zearalenone, and ochratoxin A in plant-based milk beverages

Several advanced sorbents for on-line extraction followed by chromatographic determination of citrinin, zearalenone, and ochratoxin A in a complex matrix of plant-based beverages from oat and rice milk have been compared. Twelve types of the fibrous sorbents, including polyethylene and polypropylene microfibers, polycaprolactone microfibers/polyvinylidene difluoride nanofibers composite, poly(3-hydroxybutyrate) microfibers, poly(3-hydroxybutyrate) microfibers/polypropylene microfibers composite, polycaprolactone nanofibers, polycaprolactone nanofibers doped with 7.7, 20.2, and 30.7% graphene, polyacrylonitrile nanofibers, polyurethane nanofibers, and polyamide 6 nanofibers were compared in terms of extraction recovery and cleanup efficiency with both the commercial restricted access media sorbent RP-18 ADS (RAM) and molecularly imprinted polymers (MIP). The MIP sorbent was a mixture prepared from commercial Affinimip selective for ochratoxin A and zearalenone, and home-made MIP for citrinin (1:1:1). The polymer fibers and the MIP mixture were filled in a cartridge similar in size to the commercial RAM column and the clean-up step as well as the subsequent chromatographic separation were optimized. The HPLC separation of mycotoxins was carried out using Kinetex Biphenyl (150 x 4.6 mm, core-shell particle size 5 & mu;m) analytical column followed by fluorescence detection. The excitation and emission wavelengths were set at 335/497 nm for citrinin and ochratoxin A, and 270/458 nm for zearalenone, respectively. The mobile phase used for the gradient elution of the mycotoxins consisted of 0.5% aqueous formic acid and acetonitrile. The zearalenone contaminations found in plant-based beverages ranged from 9.5 to 14.6 & mu;g L-1 and were within the tolerable limit defined by the European Union.

Automated summary

This study compared several advanced sorbents for the on-line extraction and chromatographic determination of citrinin, zearalenone, and ochratoxin A in plant-based beverages such as oat and rice milk. The extraction recovery and cleanup efficiency of twelve types of fibrous sorbents and two commercial sorbents were compared. The results showed that the zearalenone contaminations in the plant-based beverages were within the tolerable limit defined by the European Union.