基于小波变换的质谱基线校正算法研究

Baseline Correction Algorithm for Mass Spectrometry Based on Wavelet Transform

质谱仪是广泛应用于生命科学、食品安全、环境监测、工业分析、国家安全等领域的精密测量仪器。数据处理是影响质谱分析结果的关键环节,为了降低质谱仪数据采集过程中基线漂移,文章提出了一种基于小波变换的质谱基线校正算法。首先对原始质谱信号多次进行单层小波分解,同时进行单层小波重构,计算得每层的信噪比并通过信噪比比对法获得降噪后的质谱信号。接着对该信号进行多次单层小波分解,得到每层小波细节和小波近似的频率,将两个频率相除得到比值,比较每层的比值大小并选择最大比值所在层作为小波分解的最佳层数,最后将小波分解最佳层数下的小波近似系数置零后进行小波重构,获得基线校正后的质谱信号。通过实验验证发现,该算法可准确得出小波分解的最佳层数,在大幅保留真实质谱信号的基础上去除低频质谱基线以及高频噪声的干扰,质谱基线校正充分,实际应用效果明显。

The mass spectrometer is an accurate measurement instrument widely used in life sciences,food safety,environmental monitoring,industrial analysis,state security and other fields.Data processing is the critical link that affects the analysis results of mass spectrometry.In order to reduce the baseline drift during data acquisition,a baseline correction algorithm based on wavelet transform is proposed.Firstly,carry out single-layer wavelet decomposition to the original mass spectral signal several times,perform reconstruction to single-layer wavelet at the same time,calculate the signal-to-noise ratio of each single-layer,and acquire the mass spectral signal after noise reduction through the signal-to-noise ratio comparison method.Secondly,carry out single-layer wavelet decomposition to this signal several times to obtain wavelet details and the wavelet approximated frequency of each layer,divide the two frequencies to get the ratio and compare the ratio values of each layer,select the layer with the largest value as the best layer of wavelet decomposition.Finally,reset the wavelet approximated coefficient under the best layer of wavelet decomposition to zero and carry out wavelet reconstruction to obtain the mass spectral signal after baseline correction.Through the verification of experiments,this algorithm can precisely get the best layer of wavelet decomposition.Based on the retaining of real mass spectral signal as much as possible,remove the distribution of low frequency mass spectral baseline and high frequency noises;the baseline correction is sufficient and good results are achieved.