Highly Selective Ambient Mass Spectrometry Analysis Of Carbohydrates

As one of the most important biological macromolecules involved in the essence of life activities,carbohydrates participate in almost all life processes and have many functions.For example,carbohydrates,as an important bioinformatic molecule,participate in intracellular/intercellular recognition,and have a variety of physiological and pathological activities.In recent years,with the deepening of the relationship between structure and function of carbohydrates,the research of carbohydrates become an important hotspot in the field of life science.However,due to the complexity and diversity of structure,its analysis and detection has always been a great challenge.At present,soft ionization mass spectrometry and liquid chromatography-mass spectrometry are one of the most effectively methods of analyzing carbohydrates.When mass spectrometry analyzes carbohydrates,there are three key issues:1.The ionization efficiency of carbohydrates compounds is not high,which directly affects the sensitivity of mass spectrometry.2.The polymorphic ions([M+H]~+、[M+Na]~+、[M+K]~+,etc.)generated during ionization make the mass spectrum more complex and affecting the selectivity and specificity of the analysis.which is not conducive to quantitative analysis.3.Because of the low salt tolerance of traditional ion sources(such as ESI),high salt background samples cannot be analyzed.If the addition characteristics of carbohydrates and alkali metal ions can be utilized,which is ionized in a high salt background,it will be beneficial to the high sensitivity and selectivity mass spectrometry analysis of carbohydrates compounds.Paper spray ionization is the simplest ambient ionization mass spectrometric(AMS)ion source developed in recent years.It has the characteristics of strong anti-interference,small matrix effect and easy operation.In this paper,a high-selectivity ionization method for carbohydrates on paper substrate containing high alkali metal salts has been established,and high selectivity and sensitivity mass spectrometry analysis of glycans and glycoconjugates have been realized,the main research contents are as follows:The first chapter is introduction.This paper reviews the research status of carbohydrates,including their classification structure,biological significance and analytical methods,as well as their ionization behavior in mass spectrometry ion source.At the same time,the principle,application status and paper-based modification of PS-MS are introduced.In the second chapter,a highly sensitive ionization method for carbohydrates on salt-based paper was established.The structural units of carbohydrate were used as model compounds,and the paper was spray ionized by a variety of salt based metal ion loaded paper groups.It was found that the carbohydrates and alkali metal ions formed a specific additive ion during the ionization process,and the background ionization signal could be effectively reduced.A series of monosaccharides,oligosaccharides and glycosides were taken as objects to further confirm the applicability of the method.The third chapter explores the mechanism of highly selective ionization of carbohydrates on high-salt paper substrate from the perspective of structural characteristics.Polyhydroxy compounds and glycan-rings containing heteroatoms were selected as the structural model.to investigate the distance,cis-trans position and specific stereostructure of hydroxyl groups.The influence of heteroatoms on the electron distribution on the sugar ring was determined,which affected the affinity of carbohydrates molecule with alkali metal ions.In the fourth chapter,the paper spray ionization method based on high-salt paper substrate is successfully applied to the analysis of carbohydrates in the complex matrices of traditional Chinese medicine,food and biological samples.Successfully analyzed the carbohydrates in Codonopsis pilosula,the ginsenosides in Panax ginseng,the adulteration of sucrose in honey,the glucose in blood and urine of biological samples and realized the rapid semi-quantitative analysis of glucose in urine.The results show that the proposed method is highly selective for the analysis carbohydrates in complex matrices with high structural selectivity and high anti-interference ability.