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

Linzhou Zhang, Yahe Zhang, Suoqi Zhao^*, Keng H. Chung, Chunming Xu, Quan Shi^*

State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, PR China

^*Corresponding Author: email: sqzhao@cup.edu.cn (S. Zhao), Tel.: +86 10 8973 3738. email: sq@cup.edu.cn (Q. Shi), Tel.: +86 10 8973 9015. 

DOI: 10.1016/j.ijms.2014.08.030

Keywords: Apodization; Signal processing; Fourier transform ion cyclotron resonance mass spectrometry; Window function; Heavy petroleum

Abstract: 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.