Research On Data Processing Algorithm And Software Development Of Quadrupole Mass Spectrometer

Quadrupole mass spectrometry has the characteristics of high sensitivity,good specificity,and fast analysis speed,etc.In this paper,the inductively coupled plasma mass spectrometry(ICP-MS)developed in the laboratory is used as the experimental platform to study the data denoising,baseline correction,spectral peak identification,instrument correction and the development of control software.According to the needs of the project,the upper computer software of ICP-MS is designed and implemented.In this paper,the denoising algorithm,baseline correction algorithm and spectral peak recognition algorithm of mass spectrum software are studied.Aiming at the noise problem of ICP-MS signal,the threshold value,wavelet base and decomposition layer number of wavelet threshold denoising algorithm are optimized,and the optimized algorithm has good denoising performance by comparison.To solve the drift problem of detected signals,the White Top-hat filter baseline correction algorithm is implemented based on morphological filtering.The comparison shows that the algorithm can remove the drift of mass spectrum signals well.In order to separate the peak from the background and extract its key features,a local maximum peak recognition algorithm based on signal-to-noise ratio is designed and implemented.The algorithm can effectively identify the peak of mass spectrum and eliminate the error caused by accidental noise.In order to solve the problem of mass axis drift and resolution change of mass spectrometer,a method to adjust RF and DC scanning voltage of quadrupole indirectly by adjusting calibration parameters is proposed by studying quadrupole field and Matthew equation.In this method,the mass axis error and 10% peak width obtained by the spectral peak recognition algorithm in the scanning process are used as the judgment conditions,and the correction parameters are cyclically fine-tuned until the mass axis error is within the range of ±0.1 amu and the 10% peak width is within the range of 0.65～0.80 amu.In order to solve the problem that the pulse and analog calibration curves of dual-mode detector of mass spectrometer are linear but not connected,A method of detector cross calibration is proposed.The method obtains the P/A factors of elements in the scan,selects the fitting order based on Bayesian information criterion to curve fit the P/A factors,and takes the P/A factors of uncorrected elements from the fitting curves.The results show that these two calibration methods are helpful to optimize the performance of the quadrupole mass spectrometer and improve the accuracy and stability of the measurement.Based on the previous work and the research results of this paper,the software development is designed and completed.The upper computer software has the functions of parameter setting and condition monitoring,scanning and spectrum drawing,correction and storage,etc.The test verifies that the software meets the application requirements of the instrument and has good stability and scalability.