Deconvolution filters to enhance resolution of dense time‐of‐flight survey spectra in the time‐lag optimization range

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Abstract
By applying time‐domain filters to time‐of‐flight (TOF) mass spectrometry signals, we have simultaneously smoothed and narrowed spectra resulting in improved resolution and increased signal‐to‐noise ratios. This filtering procedure has an advantage over detailed curve fitting of spectra in the case of large dense spectra, when neither the location nor the number of mass peaks is known a priori. This time series method is directly applicable in the time lag optimization range, where point density per peak is constant. We present a systematic methodology to optimize the filters according to any desired figure of merit, illustrating the procedure by optimizing the signal‐to‐noise per unit bandwidth of matrix‐assisted laser desorption/ionization (MALDI) data. We also introduce a nonlinear filter that reduces the spurious structure that often accompanies deconvolution filters. The net result of the application of these filters is that we can identify new structures in dense MALDI‐TOF data, clearly showing small adducts to heavy biomolecules. Copyright © 2006 John Wiley & Sons, Ltd.