Research On Signal Feature Extraction In Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Fourier transform ion cyclotron resonance mass spectrometer is a mass spectrometer detection means which has developed rapidly in the last 30 years.Since the first time the ion cyclotron resonance technique and Fourier transform technique was applied to mass spectrometric detection,the new technology with its high-resolution mass spectrometry,high-quality detection limit,high scan speed and ease of development tandem mass spectrometry technology and other advantages is more and more widely used in life sciences,chemistry and materials science and other fields,especially plays a very important role in the study of biological molecular structure.This thesis is based on a study of the above background.According to a large number of domestic and foreign literature,we demonstrate that collision sections and high-resolution mass spectra of biomolecule ions may be obtained simultaneously by Fourier transform ions cyclotron resonance mass spectrometry.And the on collision cross section and the mass to charge(m/z)ratio represent the damping factor and frequency of the collected signal.Based on this,different methods have been proposed to extract the damping factor and frequency of ubiquitin ions with different number of charges.Specific contents are as follows:(1)This thesis presents a based on time-domain analysis algorithm for the time-domain data processing.Firstly,a fast Fourier transform(FFT)is performed on the image current signal to acquire a frequency-domain spectrum,from which the ion m/z ratio could be determined.After selecting an ion of interest,the initial phase of the corresponding mass(peak)is caluted.From frequency and phase valued,the image current signal is then modulated,so that the frequency of interest is shifted to zero.A multistep low pass filtering and down-sampling process(13 rounds)is then carried out to carefully remove other mass peaks and noise from the transient signal to get the decay profile.Next,the decay profile is fed into a least-squares fitting module to calculate the decay factor.With a single-frequency signal and the multi-frequency signal to verify the algorithm,it could obtain more accurate feature information and control the curve fitting error in 10'6 magnitude.(2)Then a frequency domain interpolation is presented for the image current signal processing.The signal is weighted by Hanning window befor the fast Fourier transform and the frequency and the damping factor are obtain by frequency domain interpolation.Next,a typical decaying signal and the single-frequency signal are simulated with a good result.Then the multi-frequency signal in frequency domain is fed into a least-squares fitting module to calculate the decay factor.Comparing to the time-frequency analysis algorithm,it has a better result.(3)Finally,a FPGA-based ignal processing system evaluation board is designed.It includes an analog front end processing module,AD converter module,data acquisition and transmission module,and Labview-based PC data display interface design.