Department of Physics, National Dong Hwa University, Shoufeng, Hualien, Taiwan, Republic of China.
J Am Soc Mass Spectrom. 2012 Nov;23(11):1855-64. doi: 10.1007/s13361-012-0455-2. Epub 2012 Aug 21.
We adopt an orthogonal wavelet packet decomposition (OWPD) filtering approach to cancel harmonic interference noises arising from an AC power source in time domain and remove the resulting rf voltage interference noise from the mass spectra acquired by using a charge detection frequency-scan quadrupole ion trap mass spectrometer. With the use of a phase lock resampling technique, the transform coefficients of the rf interference in signals become a constant, exhibiting a shift of the baseline in different rf phases. The rf interference is therefore removable by shifting the baselines back to zero in OWPD coefficients. The approach successfully reduces the time-domain background noise from 1367 electrons (rms) to 408 electrons (rms) (an improvement of 70 %) and removes the high frequency noise components in the charge detection ion trap mass spectrometry. Unlike other smoothing or averaging methods commonly used in the mass-to-charge (m/Ze) domain, our approach does not cause any distortion of original signals.
我们采用正交小波包分解（OWPD）滤波方法来消除来自交流电源的谐波干扰噪声在时域中，并从使用电荷检测频率扫描四极离子阱质谱仪获得的质谱中去除由此产生的射频电压干扰噪声。通过使用锁相重采样技术，信号中射频干扰的变换系数变为常数，在不同的射频相位下显示出基线的偏移。因此，通过将 OWPD 系数中的基线回移到零，就可以去除射频干扰。该方法成功地将时域背景噪声从 1367 个电子（rms）降低到 408 个电子（rms）（提高了 70%），并去除了电荷检测离子阱质谱中的高频噪声分量。与通常在质荷比（m/Ze）域中使用的其他平滑或平均方法不同，我们的方法不会对原始信号造成任何失真。
