title: Heuristic charge assignment for deconvolution of electrospray ionization mass spectra.
abstract: We propose a new algorithm for deconvolution of electrospray ionization mass spectra based on direct assignment of charge to the measured signal at each mass-to-charge ratio (m/z). We investigate two heuristics for charge assignment: the entropy-based heuristic is adapted from a deconvolution algorithm by Reinhold and Reinhold;10 the multiplicative-correlation heuristic is adapted from the multiplicative-correlation deconvolution algorithm of Hagen and Monnig.6 The entropy-based heuristic is insensitive to overestimates of z(max), the maximum ion charge. We test the deconvolution algorithm on two single-component samples: the measured spectrum of human beta-endorphin has two prominent and one very weak line whereas myoglobin has a well-developed quasi-gaussian envelope of 17 peaks. In both cases, the deconvolution algorithm gives a clean deconvoluted spectrum with one dominant peak and very few artefacts. The relative heights of the peaks due to the parent molecules in the deconvoluted spectrum of a mixture of two peptides, which are expected to ionize with equal efficiency, give an accurate measure of their relative concentration in the sample.
authors.affiliation: Faculty of Informatics, University of Ulster at Jordanstown, Newtownabbey BT37 0QB, Northern Ireland.
authors.forename: Huiru
authors.initials: H
authors.lastname: Zheng
authors.forename: Piyush C
authors.initials: PC
authors.lastname: Ojha
authors.forename: Stephen
authors.initials: S
authors.lastname: McClean
authors.forename: Norman D
authors.initials: ND
authors.lastname: Black
authors.forename: John G
authors.initials: JG
authors.lastname: Hughes
authors.forename: Chris
authors.initials: C
authors.lastname: Shaw
mesh_terms: D000465:Algorithms; D000818:Animals; D001920:Bradykinin / Q000032:analysis; D025802:Electric Capacitance; D004553:Electric Conductivity; D019277:Entropy; D006801:Humans; D007477:Ions; D009211:Myoglobin / Q000032:analysis; D010455:Peptides / Q000737:chemistry; D015203:Reproducibility of Results; D021241:Spectrometry, Mass, Electrospray Ionization / Q000706:statistics & numerical data*; D001615:beta-Endorphin / Q000032:analysis
chemical_list: D007477:Ions; D009211:Myoglobin; D010455:Peptides; D001615:beta-Endorphin; D001920:Bradykinin