Detection Of Mycotoxins By Liquid Chromatography-mass Spectrometry Based On Chemical Coding Labelin

The widespread dissemination and pathogenicity of mycotoxins have posed a major threat for human society which pose significant challenges for human health.New methods for rapid,sensitive and accurate detection of mycotoxins is urgently needed to meet the requirements of food safety and risk assessment in new situation.Mass spectrometry（MS）and tandem mass spectrometry（MS/MS）have been used as commonly techniques for the quantitative analysis and structural characterization of various compounds due to their high sensitivity,excellent selectivity,fast response and high speed.To achieve simultaneous detection and quantification of multiple analytes in complex matrices,it is usually combined with high performance liquid chromatography（HPLC）and gas chromatography（GC）.In recent years,chemically encoded derivatization techniques that attracted widespread attention and recognition from researchers have shown great potential in the aspect of improving detection sensitivity,quantitative accuracy and overcoming matrix effects.In this work,four methods for the simultaneous detection of six mycotoxins,ochratoxin A（OTA）,ochratoxin B（OTB）,fumonisin B1（FB1）,fumonisin B2（FB2）,zearalenone（ZEN）and zearalenone（ZAN）,was established by combining chemical coding derivatization with mass spectrometry,which provides methodological support for food safety and monitoring mycotoxins.This paper focuses on the following work:Chapter 1:The introduction of mycotoxins as a major risk for human health and economic development is first given.Then current status and progress of mycotoxins research,and effective measures to overcome matrix effects are reviewed.Finally,the basis for the selection of the research and main content of this work are briefly expounded.Chapter 2:Three pairs of chemically coded derivatization reagents designed and prepared by our research group were characterized and identified.The six sulfonyl chloride chemical derivatives d₃-10-methyl-acridone-2-sulfonyl chloride（d₃-MASC）,10-methyl-acridone-2-sulfonyl chloride（d₀-MASC）,Dansyl chloride（d₀-Danyl-Cl）,d₄-Dansyl chloride（d₄-Danyl-Cl）,8-quinolinesulfonyl chloride（QSCl）and3-methylquinoline-8-sulfonyl Chloride（MQSCl）were comprehensively compared to evaluate their mass spectrometry sensitization performance and feasibility as coding labeling reagents.Chapter 3:A new method for the simultaneous determination of six mycotoxins has been established by using ultra performance liquid chromatography tandem quadrupole mass spectrometry（UHPLC-QQQ-MS/MS）with d₀-Danyl-Cl and d₄-Danyl-Cl as isotope-coded derivatization reagents,and method validation that including linearity,detection limits（LODs）,quantitative limits（LOQs）,matrix effect,precision and accuracy was performed.The new method was successfully applied to the determination of mycotoxins in three types of cereal samples,corn,wheat and sorghum.Chapter 4:A new method for the simultaneous determination of six mycotoxins was established,which using d₀-MASC and d₃-MASC as isotopically coded derivatization reagents,detecting by ultra performance liquid chromatography/quadrupole time-of-flight tandem mass spectrometry（UHPLC/Q-TOF-MS）.The method was used to analyze flour samples,successfully realizing the accurate quantification of targeting six mycotoxins.In addition,other toxins such as zearalenol were also identified and characterized by retrospective analysis of the data,extraction of light/heavy coding features,and combination with database information.The results indicate that the method has great potential for non-targeted analysis.Chapter 5:A quantitative method for the simultaneous determination of six mycotoxins was developed by high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）using QSCl and MQSCl as homologue-encoding derivatives（twins coding reagents）,which was successfully used for the detection of mycotoxins in a variety of cereal-based feeds.Results indicated that the twins coding strategy was equivalent with previously described iostope-coded derivatization reagents in improving sensitivity and accuracy.The detection limits and quantitative limits were 0.01065-0.01783μg/kg and 0.03195-0.05343μg/kg,respectively,with good linearity and accuracy of 97.6-106.9%.Meanwhile,the twins coding strategies based on QSCl and MQSCl are cheaper and have more promotion value than before.Chapter 6:A high-throughput analytical method for the quantitative detection of three mycotoxins was established using flow injection-tandem mass spectrometry（FIA-MS/MS）with d₀-MASC and d₃-MASC as iostope-coded derivatization reagents.The derivatized samples were desalted by a dispersive liquid-liquid microextraction process to be compatible with FIA-MS/MS analysis.Meanwhile,the analytes were further enriched,which greatly improved the sensitivity of the method.the isotopic internal standard was used to correct for matrix effects to ensure its accuracy.The established method was fully validated for the rapid detection of the three mycotoxins within 2 min and successfully used for bean.The method has short analysis time and high throughput.And it can provide technical support for food safety monitoring and rapid screening of mycotoxins.