Design And Performance Of Exploration Of A Linear Ion Trap Mass Spectrometer

Mass spectrometer is the representative of modern analytical instruments with its application field referring to medicine,geology,chemistry,environmental protection and military technique etc.Mass analyzer is the core component of mass spectrometers,and also decides the performance of mass spectrometers.As a kind of mass analyzers,linear ion trap has uniquely great ion capacity and high trapping efficiency.However,the hyperboloid structure of the linear ion trap requires a high precision which cause the difficulty for processing and assembling.So the researches of simplifying the electrode structure become a hot-spot in the fields,and have developed many new linear ion traps,such as RIT,TeLIT and so on.However,the performances of mass analysis like mass resolution are affected seriously by inside high order fields induced by simplified electrodes.A new linear ion trap with simple structure and great mass analytical properties was proposed,and a linear ion trap mass spectrometer was developed.The main contents of this paper are as follows:(1)It was assumed that the hyperboloid electrodes could be placed by round electrodes,and verified this assumption by theoretical analysis.The model of HreLIT was built by software SIMION,and also the tracks of ion in the electric field and mass spectrum were simulated by AXSIM.The results showed that mass resolution of 2858 was achieved,when the scan rate was 1500Th/s.So,it was showed that the assumption of round electrodes replacing the hyperboloid electrodes could be feasible.(2)An ESI-HreLIT mass spectrometer was developed to verify the performance of Hre LIT.The process of designing and building this mass spectrometer system was described in detail,including the processing and assembling of Hre LIT,and the setup of instrument system which included three-stage vacuum chamber,ESI ionization,ion guide system and circuit system.(3)The performance tests of ion radial ejection on ESI-HreLIT mass spectrometer were investigated by changing scan rate and testing dynamic mass range,and three-stage mass spectrometry was also successfully performed in HreLIT.The experimental results showed that a mass resolution of 4350 and a mass range of over 2800 u were achieved on ESI-HreLIT mass spectrometer.Furthermore,the CID efficiency of MS2 was 78% and the CID efficiency of MS3 was 59%.(4)The performance tests of ion axial ejection on ESI-HreLIT mass spectrometer were investigated,and the influence of voltage parameters on the ion axial ejection efficiency was also studied,such as voltage on back lens,resonant frequency,scan rate and so on.It was showed that ion axial ejection was realized in HreLIT with a great mass resolution in accordance with ion radial ejection,and the influence rules of voltage parameters in ion axial ejection efficiency were summarized by the experimental results.All the research results indicated that HreLIT of simple structure could obtain high mass resolution and showed a great performance of mass analysis both in radial ion ejection and axial ion ejection.Among numerous linear ion traps of simple electrode structures,HreLIT would have broader prospects for development with its better analysis capabilities.