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Factors that affect molecular weight distribution of Suwannee river fulvic acid as determined by electrospray ionization/mass spectrometry

Analytica Chimica Acta

By:
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DOI: 10.1016/j.aca.2004.06.065

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Abstract

Effects of methylation, molar response, multiple charging, solvents, and positive and negative ionization on molecular weight distributions of aquatic fulvic acid were investigated by electrospray ionization/mass spectrometry. After preliminary analysis by positive and negative modes, samples and mixtures of standards were derivatized by methylation to minimize ionization sites and reanalyzed.Positive ionization was less effective and produced more complex spectra than negative ionization. Ionization in methanol/water produced greater response than in acetonitrile/water. Molar response varied widely for the selected free acid standards when analyzed individually and in a mixture, but after methylation this range decreased. After methylation, the number average molecular weight of the Suwannee River fulvic acid remained the same while the weight average molecular weight decreased. These differences are probably indicative of disaggregation of large aggregated ions during methylation. Since the weight average molecular weight decreased, it is likely that aggregate formation in the fulvic acid was present prior to derivatization, rather than multiple charging in the mass spectra. ?? 2004 Elsevier B.V. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Factors that affect molecular weight distribution of Suwannee river fulvic acid as determined by electrospray ionization/mass spectrometry
Series title:
Analytica Chimica Acta
DOI:
10.1016/j.aca.2004.06.065
Volume
523
Issue:
2
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
269
Last page:
278
Number of Pages:
10