Mass Spectra Study On Micro Unknown Constituents And Degradation Products In Bulk Drugs

It is important to undertake qualitative analysis and quantitative analysis of drug impurities.High-performance liquid chromatography,when combined with electrospray ion trap mass spectrometry,possesses high separation efficiency and great qualitative capability.As it holds the advantages of high sensitivity,relatively short analysis time,low sample amount,and the ability to obtain structural information,HPLC/ESI-MS~n has been widely used as a powerful tool in various online drugs analysis.In this dissertation,the liquid chromatograpy/electospray tandem mass spectrometry(HPLC/ESI-MS) method was developed to identify the degradation products of crude drugs:Imipenem and Meropenem,also used to identify the impurities of Eprosartan and Levofloxacin carboxylic acid.The details are listed in the following:Partâ… A method based on HPLC/ESI-MS~n and nuclear magnetic resonance (NMR) has been established to analyze the degradation products of Imipenem and Meropenem in an acid solution,as well as the generation procedures involved.Offline Fourier transform ion cyclotron resonance mass spectrometry(FTICR-MS) was also performed to assign the accurate elemental compositions.The proposed structures by were confirmed by NMR technology.After conducting the tracing detection experiments,the structures of intermediate products in the acid degradation procedure were then identified.Partâ…¡Three competitive fragmentation methods of Eprosartan in the positive mode were summarized by electrospray mass spectrum multistage fragmentation experiments(ESI-MS~n).In this phase,HPLC/ESI-MS~n and NMR technologies were employed to identify the chemical structure of a microimpurity by comparing the spectral data of Eprosartan and its impurity.Partâ…¢The chemical structure of the microimpurity in Levofloxacin carboxylic acid was identified by analyzing minor differences between Levofloxacin and the impurity in the NMR spectrometry.Furthermore,two competitive mass fragmentation methods in the positive mode were summed up by multistage mass fragmentation experiments.In addition,the recent progress of the LC/MS~n technique in pharmaceutical analysis was reviewed in brief.