Bioanalytics of mycotoxins and development of dedicated analyte-selective molecularly imprinted materials for solid-phase extraction

Mycotoxins are secondary metabolites produced by several fungal species, growing on agricultural products during cultivation, harvest, transport or storage. Ochratoxin A (OTA) is a mycotoxin of great natural abundance and can be found in various plant products. Due to its frequent occurrence and toxic properties many countries have set up tolerance levels for OTA. Thus, the need for sensitive analytical and in particular selective sample preparation methods for analyte enrichment and removal of interfering matrix compounds is obvious. Molecular imprinting generates polymeric matrices that can selectively recognize and bind target molecules. It was previously demonstrated that molecularly imprinted polymers (MIPs) can be employed in sample preparation. MIPs capable of recognizing OTA have been prepared using an analyte mimic approach. Crucial to the success was the introduction of a novel class of quinuclidine-derived functional monomers which utilize ionic binding increments and hydrophobic interactions for selective recognition of the target analyte and its mimics. Since optimization of SPE procedures demonstrated the convenient use of several solvent systems, the developed MIPs represents an enrichment for the field of mycotoxin analysis. Zeranol has been widely adopted as a growth stimulant for cattle and other animals due to its anabolic and estrogenic properties. Application of zeranol has been banned in the European Union since 1985. Researchers, however, found that the illegal administration of this anabolic agent may not be the only source of zeranol residues in biologically relevant matrices. Previously, it was demonstrated that zeranol was also formed in vivo from the mycotoxins zearalenone (ZON) and α-zearalenol that are carried over from mycotoxin contaminated feed into the animal body. A fast, robust and sensitive LC-MS method for the determination for these compounds in urine and tissue samples has been developed. Crucial for the achievement of low detection limits was the careful selection of suitable fragment ions and the chromatographic separation of all analytes prior to mass spectrometric analysis. Simple sample pre-treatment and unambiguous analyte identification were the basis to monitor these analytes during a feeding study with pigs enabling a detailed investigation of ZON and its metabolites in this animal species. (author)