Mass Spectrometry Analysis Of Endocrine Disruptors Based On Stable Isotope Labeling Techniques

Endocrine disrupting compounds（EDCs）are a kind of exogenous chemicals that can disturb the organism’s endocrine system.A variety of chemical raw materials,products and by-products used in industrial processes,such as polychlorinated biphenyls（PCBs）,polybrominated biphenyls（PBBs）,dioxins,alkylphenols,perfluorocarboxylic acids are listed as EDCs.EDCs usually exist in trace levels in complex matrices and are difficult to detect.Mass spectrometry（MS）can provide not only retention time information,but also mass-to-charge ratio,and thus plays an increasing important role in EDCs analysis.However,the accuracy of MS was affected by matrix effect.The ionization efficiency of the same compound varies from samples to standard solutions because of the different matrices between them.Stable isotope labeling（SIL）technique is an effective tool to overcome matrix effect.In SIL analysis,there is a pair of labeling reagents which have identical functional groups and differ only in isotopic composition.The light one was used for the labeling of standard,while the heavy version was used for the labeling of sample.After that,sample and standard were mixed and analyzed.Because of the similar chemical property of the labeling reagent pair,sample and standard have identical retention time,but can be distinguished by MS because of the different molecular weight.This property allows samples and standards to undergo exactly the same ionization process with the same ionization efficiency,overcoming matrix effects due to competing ionization and improving the accuracy of analytical results.In this thesis,SIL-labelled reagents for phenols,aldehydes and carboxylic acids were designed and prepared to improve the accuracy of mass spectrometry analysis of EDCs during High performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）,and were applied for the analysis of real samples.Details of the work are as follows:Chapter one:An overview of EDCs and their analytical techniques is briefly described.The application of high performance liquid chromatography-mass spectrometry and stable isotope labeling techniques in the analysis of EDCs is summarized,and the idea of the selected topic and the main work of this thesis are described.Chapter two:A positively charged stable isotope labelling pair,d₀/d₃-succinimidyl p-trimethylaminobenzoate（d₀-DPTBA/d₃-DPTBA）,was designed and synthesised and structurally confirmed.The isotopically labelled reagents were used for the analysis of alkylphenols and all lightly labelled standards had fragment ions with an m/z of 148.1 and all heavily labelled samples had fragment ions with an m/z of 151.1.All labelled products had the same fragmentor（140 V）and collision energy（40 V）.It was used in the HPLC-MS/MS analysis of alkylphenols in edible oils with detection limits between 1.5–1.8 ng/L,recoveries between 88.6–95.3%and matrix effects between 96.2–99.6%.Chapter three:A stable isotope labelling reagents deuterated dansulfonyl hydrazide（d₆-DNSH）,was synthesized from deuterated dansulfonyl chloride and combined with commercially dansulfonyl hydrazide（d₀-DNSH）for stable isotope labeling analysis of aldehydes.The lightly labelled standards all had fragment ions with an m/z of 171.1 and the heavily labelled samples all had fragment ions with an m/z of 177.1.All labelled products had the same all labelled products had the same fragmentor（140 V）and collision energy（35 V）.A multiple reaction monitoring（MRM）analytical method for aldehydes was developed using formaldehyde to decanal aliphatic aldehydes and applied to the proposed target analysis of unknown aldehydes,and 21 aliphatic aldehydes were detected in food samples.Based on the results of the proposed targeting analysis,MRM analytical methods were developed for 21 fatty aldehydes with detection limits between 8.9–14.4 ng/L,recoveries between 84.7–96.4%and matrix effects between 81.9–102.6%.Chapter four:COF Tp Pa was synthesized from 1,3,5-triformylresorcinol and p-phenylenediamine and then further reacted with 3-chloropropyltriethoxysilane to introduce chlorine atoms into COF Tp Pa.T The chlorinated COF reacted with1-methylimidazole to synthesize ionic liquid modified covalent organic polymer（COF Tp Pa-Ct@Mm）.This retains the high specific surface area and large conjugated structure of COF,and also introduces the abundant charge of ionic liquids,which can interact with perfluorocarboxylic acids through electrostatic and hydrophobic forces to achieve selective enrichment.It was used for the stable isotope labelling analysis of perfluorinated carboxylic acids in cod liver oil with detection limits between 7.5–21.8ng/L,recoveries between 86.3–95.8%and matrix effects between 88.1–101.8%.