Get access

Adduct simplification in the analysis of cyanobacterial toxins by matrix-assisted laser desorption/ionization mass spectrometry

Authors

  • Karen L. Howard,

    1. Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY 13210, USA
    Search for more papers by this author
  • Gregory L. Boyer

    Corresponding author
    1. Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY 13210, USA
    • Faculty of Chemistry, SUNY-ESF, 1 Forestry Drive, Syracuse, NY 13210, USA.
    Search for more papers by this author

Abstract

A novel method for simplifying adduct patterns to improve the detection and identification of peptide toxins using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry is presented. Addition of 200 µM zinc sulfate heptahydrate (ZnSO4 · 7H2O) to samples prior to spotting on the target enhances detection of the protonated molecule while suppressing competing adducts. This produces a highly simplified spectrum with the potential to enhance quantitative analysis, particularly for complex samples. The resulting improvement in total signal strength and reduction in the coefficient of variation (from 31.1% to 5.2% for microcystin-LR) further enhance the potential for sensitive and accurate quantitation. Other potential additives tested, including 18-crown-6 ether, alkali metal salts (lithium chloride, sodium chloride, potassium chloride), and other transition metal salts (silver chloride, silver nitrate, copper(II) nitrate, copper(II) sulfate, zinc acetate), were unable to achieve comparable results. Application of this technique to the analysis of several microcystins, potent peptide hepatotoxins from cyanobacteria, is illustrated. Copyright © 2007 John Wiley & Sons, Ltd.

Ancillary