Sharp Glass Electrospray Ionization For Mass Spectrometry And MALDI-MS Imaging Of Berberine In Coptidis Rhizoma

Mass spectrometry ionization method and mass spectrometry imaging(MSI)technology has been rapid development.Traditional mass spectrometric ionization methods include electrospray ionization(ESI),atmospheric pressure chemical ionization(APCI),matrix-assisted laser desorption ionization(MALDI)and so on.In recent years,many new methods of electrospray mass spectrometry have been developed,which include paper spray,leaf spray,wood spray and blade spray that are simple in structure,without spray gas,easy to build,and can be more convenient for mass spectrometry analysis.In addition,mass spectrometry imaging technology has become an important method for studying drug metabolism,peptide and protein distribution,small molecule substances distribution and so on.Matrix selection and different matrix coating methods are the key technologies and important research contents in MALDI-MSI.Research in mass spectrometry ionization and mass spectrometry imaging is beneficial to mass spectrometry technology in both research depth and more application fields.The thesis includes sharp glass tip electrospray mass spectrometry ionization and MALDI-MSI.In terms of the sharp glass tip electrospray mass spectrometry ionization,3 kinds of sharp glass tip electrospray ionization devices were built for direct mass spectrometry analysis using sharpened slide glass,slender capillary and sharp dropper.Through the simulation experiment and mass spectrometry experimental investigation,the influence of various experimental conditions on the mass spectrometry peak response(ionization effect)was studied.When the diameter of electrospray glass tip is less than 0.24 mm,the MS peak can be well obtained at the distance between the electrospray glass tip and the MS sample inlet as 10 mm,and the electrospray voltage as 4.5kV,the electrospray glass tip angle as about 5°-7.5°(upper at back)and the left and right angle as 0°,and the sample solution concentration 0.1 mg/ml(containing1% formic acid for positive ion detection,or ammonium hydroxide for negative detection).Using both positive and negative ion modes,the quinine,mandelic acid,benzoin,phenylalanine and other different types sample solution were MS analyzed.The result shows that quinine,mandelic acid,benzoin,phenylalanine,tartaric acid,2,5-dihydroxybenzoic acid(DHB)and tangeretin could be detected in positive ion mode using sharp glass tip electrospray.DHB,phenylalanine,tartaric acid andmandelic acid were detected in negative ion mode.Sharp slide glass electrospray is suitable for measuring the stable sample in the air,slender capillary electrospray and sharp dropper electrospray is suitable for detecting samples solution with low viscosity and even instable sample.Using the method,the extraction solution of propranolol hydrochloride tablet and berberine hydrochloride tablet were directly MS analyzed.The results show that the sharp glass electrospray method the advantages as without carrier gas used,simple structure,easy to build and operate,rapid,anti-cross pollution,and can be conveniently used for MS analysis.In MALDI-MSI,the distribution of berberine in Chinese herbal medicine Coptidis rhizoma was studied,and 4 kinds of matrix coating methods were investigated: dry drop method,spray gun method,sublimation method and ultrasonic spray method.According to the results,the characteristics of four kinds of matrix coating were compared,and then distinguished the distribution of berberine in Coptidis rhizoma.The results show that the distribution of berberine in Coptidis rhizoma mainly in the interior,and less in the epidermis.For dry drop method,the operation is very simple.However,it is easy to cause uneven coverage of the matrix,which may result in error.Spray gun method can cover the matrix more uniform and its operation is also simple.The sublimation method can uniformly cover the matrix on the sample surface,but requires specific matrix and conditions that include the mass of matrix,the temperature and time of sublimation.Ultrasonic spray method is similar to spray gun method.Compared with spray gun method,the ultrasonic spray method spray velocity and fog droplets is smaller,the matrix coverage more uniform,which is worthy of further study.In the thesis,3 kinds of sharp glass tip electrospray ionization methods are proposed,which provide new and effective techniques for ionization in mass spectrometry.On the other hand,4 kinds of matrix covering methods for MALDI-MSI are compared,which provides an important experimental basis for the further research of mass spectrometry imaging.