A Parameters Control System Of Extractive Electrospray Ionization Based On ARM And μC/OS-Ⅱ

Extractive electrospray ionization(EESI)is an ionization technology that can directly analyze the mass spectrometry of complex matrix sample without any sample pretreatment.The parameters of EESI source are usually adjusted and optimized to achieve a better detection effect in EESI experiments according to the physical and chemical properties of the sample.The researches show that the ionization voltage,temperature and humidity,the flow rate of sample and reagent,gas pressure and space position parameters of EESI source have significant influence on EESI-MS analysis results.However,the development of EESI technology is limited seriously by the lacking of integrated ions source system which can precisely adjust the EESI source pressure,temperature and other parameters.On the basis of the performance requirements of EESI source,the technical index of the parameters control system is presented,and the overall design scheme of EESI source parameters control system based on ARM and μC/OS-Ⅱ is proposed in this article.Considering the system’s performance requirements like cost performance,development difficulty of the system and so on,the STM32F407ZGT6 microprocessor is selected as the hardware of the hardware system,and the hardware circuit of each functional unit is designed.The human-computer interaction interface and application program of the system are developed based on μC/OS-Ⅱ real-time operating system and μC/GUI graphical interface system software platform.Finally,the hardware and software performance of the EESI source control system were tested.The results show that the hardware circuit modules can function well,the software GUI interface achieves the display and touch function of the parameter control interface,and the human-computer interaction performs well.The temperature parameters of the system are adjustable from room temperature to 200 ℃with the accuracy of ±1℃,high voltage control ranges from 0 to 6 kV with the accuracy of ±2%;and humidity detection accuracy is ±3% RH.The parameter control system was coupled to a linear ion trap mass spectrometer(LTQ-MS)to build a thermol-assisted EESI-MS experimental platform andthe standard amino acids sample was used to test it.Comparing with the normal EESI-MS,the experimental results show that the system effectively solves the problem that the existing EESI source can not control the temperature,and it enhances the EESI-MS signal intensity of amino acid,improves the detection sensitivity of EESI source,and provides the condition for broadening the application scope of EESI technology and commercialization of domestic ion source.