Effect of apodization on FT-ICR mass spectrometry analysis of petroleum

• Systematic test of apodization on both simulated and actual complex mixture FT-ICR signals.
• Effect of apodization on 13C isotope ratio is negligible.
• Complex FT-ICR analysis should sacrifice dynamic range to increase resolving power.
• Low dynamic window functions are recommended for less resolving power reduction while ensuring correct peak selection.

Apodization is a generally applied signal processing method in FT-ICR MS (Fourier transform ion cyclotron resonance mass spectrometry) analysis for complex petroleum samples that is used to lower the spectral leakage and smoothen the spectrum line shape. Present study evaluates the effect of apodization on the FT-ICR MS results through a systematic examination on both simulated and actual heavy petroleum signals. The result shows that the resolving power, instead of the dynamic range, is the key factor for heavy petroleum FT-ICR MS analysis due to the severe peak overlapping. Window functions with high dynamic range will reduce the resolving power so that many of the species cannot be detected. The improvement on accuracy of apodization with peak intensity is negligible and all the window functions have similar intensity error. Low dynamic range window functions perform better for FT-ICR MS analysis since they have less resolving power reduction and the spectral leakage is eliminated to ensure correct peak selection. Sine-bell and low beta value Kaiser window functions are recommended for complex mixtures.

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