Research On A New Sample Pretreatment Method And Its Application In The Analysis Of Mycotoxins

Mycotoxins are metabolites produced by the growth of fungi in food or feed.When the grain is not sufficiently dried at harvest or when the temperature or humidity is too high during storage and transportation,the fungi infected with the grain will grow rapidly and produce toxins at the same time.Mycotoxins affect a variety of crops,most of which are major commodities consumed by humans and animals.The growth of fungi depends on appropriate environmental conditions,which can cause mycotoxins to be produced in different geographical areas.However,the globalization of food trade makes mycotoxins a worldwide problem.Therefore,rapid and sensitive detection of mycotoxins is of great significance in the fields of food and health.However,the metabolic process of fungi is complex,and there are numerous modified forms of each type of toxin,which we call hidden forms of mycotoxins.The current standard methods only focus on a few kinds of toxin analytes,but don’t pay attention to the hidden form of toxins.Due to the complexity of sample matrix and the low content of analyte,there are still many problems in the actual detection.The detection of mycotoxins has been a research hotspot in analytical chemistry.Therefore,it is necessary to develop a new method for detecting mycotoxins with high sensitivity and accuracy.As more and more mycotoxins have been discovered,the research on pathological toxicology is getting deeper and deeper,which requires higher sensitivity and accuracy of analysis and detection.At present,the analytical methods of mycotoxin include immunochemical-based techniques and chromatography-based techniques.Immunochemistry-based technology is mainly used in routine control and rapid and on-site detection.And chromatography-based techniques not only identify new or modified compounds by tandem mass spectrometry;but also enable sensitive,accurate,and selective determination of mycotoxins.However,due to the extremely low content of mycotoxins in actual samples,solid phase extraction enrichment and chemical derivative sensitization are often used to improve the sensitivity of the method.In this paper,two kinds of metal organic framework materials(MOFs)were used as absorbents for the sample pretreatment,and three derivatives were used for pre-column derivatization of mycotoxins in food and feed.A new method for the sensitive determination of fumonisin,ochratoxin and zearalenone was established combine with high performance liquid chromatography-fluorescence detection(HPLC-FLD).The specific work is as follows:Chapter one: Briefly introduced the production and distribution of mycotoxins,the main types of mycotoxins,their harmfulness to humans and animals,as well as the current research status of mycotoxins.At the same time,the application of sample pretreatment and pre-column derivatization in the detection of mycotoxins is briefly described.Chapter two: The MOFs material UiO-66 was successfully prepared and characterized.And UiO-66 was used as a dispersed solid phase microextraction to establish a rapid enrichment method for two ochratoxins.The sensitive HPLC-FLD detection was achieved by combine with dansyl-Cl derivatization.The rapid,sensitive qualitative and quantitative analysis of two Ochratoxins in vegetable oils has been successfully realized.Chapter three: The MOFs material MIL-101 was successfully prepared and characterized.A filter-based dispersive solid-phase extraction method was developed with MIL-101 as adsorbent for the enrichment of two fumonisins.Fluorescence detection was carried out by derivatization with a pre-column derivatization reagent 1-methylphenamimidazole-2-benzoic acid succinimide active ester(PBIA-Osu)prepared in the laboratory.The method has been applied to the detection of actual samples.It has been proved that the method can quickly and efficiently determine two kinds of fumonisins in feed.Chapter four: A derivatization reagent butyl-1,8-naphthalene diamide-4-oxime(NBHNA)suitable for carbonyl labeling was prepared and characterized.NBHNA itself has no fluorescent signal,and it combines with a carbonyl compound to produce a turn-on type fluorescence response.NBHNA was successfully used as a pre-column derivatization reagent for the rapid labeling of zearalenone.The fluorescence signal of the derivative was greatly enhanced compared with the intrinsic fluorescence of zearalenone.The detection sensitivity of the method based on NBHNA derivatization has been greatly improved,and the limit of detection can reach 0.1 μmol/L.