Development And Application Of Data Processing System For Quadrupole Mass Spectrometer

As advantages of simple structure and flexible applications,the quadrupole mass spectrometer has become one of the most widely used mass spectrometers.Mass spectral signals are extremely susceptible to noise interference during the generation and transmission process,which can causes distortion of the original mass spectral data.The data processing system of the instrument can reduce noise interference,and its performance directly affects the analysis results of the instrument.Most traditional quadrupole mass spectrometers use software processing methods,which run the operating system and data processing operations simultaneously in CPU,and these methods have many advantages such as high software integration,convenient development and debugging,etc.However,traditional methods also have problems such as long delays and large resource consumption by means of the impact of serial instruction execution methods.It is difficult to meet some real-time and online analysis requirements,and it is easy to slow down the system response.The use of higher-performance CPUs can alleviate the tight computing resources,but it will also increase the system size and power consumption,which is not conducive to the future miniaturization of the instrument.In order to improve the real-time performance and system efficiency of data processing,this paper develops a data processing system for quadrupole mass spectrometer based on FPGA,and has carried out related applications on multiple quadrupole mass spectrometer instrument platforms.Firstly,a small quadrupole mass spectrometer instrument platform has been set up in this paper,and key components such as the ion source,mass analyzer and vacuum system are selected based on the principle of the instrument.Researched composite transimpedance current amplification technology and anti-aliasing filtering technology,and designed weak signal acquisition circuit.The FPGA chip is used to carry the data processing system,which improves the structure of the control system.After testing,the mass scanning range of the instrument platform reached 550 amu and the resolution reached 0.6 amu,all of which met the expected targets.A data processing system based on FPGA chip is developed in this paper,which realizes real-time digital filtering with microsecond delay.The system is jointly designed and developed by MATLAB and Quartus Prime software.The coefficients are calculated by the Filter Designer toolbox,and the filtering operation is performed by the FIR II IP core.The problem of output signal distortion is solved by calculating and intercepting some results.An automatic digital filter coefficient generation algorithm is designed based on Verilog HDL language,which simplifies the digital filter design process.The software for mass spectrometry data analysis was designed using MATLAB software,and the peak identification and signal-to-noise ratio analysis were realized.After system integration testing,the power consumption increased by 190 mW,accounting for only 1.7% of the total power consumption of the control system.The data processing system was applied to a small quadrupole mass spectrometer platform,a GC-MS instrument and a Q-LIT mass spectrometer,respectively,and the detection and analysis experiments of perfluorotributylamine,octafluoronaphthalene solution and reserpine solution were carried out.The baseline and mass spectrometry data before and after data processing are compared and analyzed in this paper.The results show that the standard deviation of the baseline noise is attenuated by more than half and the SNR of the mass spectrum peaks increased by 1x,2x,and 5x,respectively,and the signal quality was greatly improved.At the same time,the validity and versatility of the data processing system were verified.