Improved protonation, collision-induced decomposition efficiency and structural assessment for ‘red tide’ brevetoxins employing nanoelectrospray mass spectrometry

✍ Scribed by Weiqun Wang; Richard B. Cole

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 239 KB
• Volume: 41
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/jms.1047

✦ Synopsis

Abstract

Brevetoxins are a group of natural neurotoxins found in blooms of red tide algae. Previous electrospray mass spectrometry (ES‐MS) studies show that all brevetoxins have high affinities for sodium ions, and they form abundant sodium adduct ions, [M + Na]^+^, in ES‐MS, even when trace contamination is the only source of sodium ions. Attempts to obtain informative product ions from the collision‐induced decomposition (CID) of [M + Na]^+^ brevetoxin precursor ions resulted only in uninformative sodium ion signals, even under elevated collision energies. In this study, a nano‐ES‐MS approach was developed wherein ammonium fluoride was used to form cationic [M + NH~4~]^+^ adducts of brevetoxin‐2 and brevetoxin‐3; a significant increase in the abundance of protonated brevetoxin molecules [M + H]^+^ also resulted, whereas the abundance of sodium adducts of brevetoxins [M + Na]^+^ was observed to decrease. Under CID, both [M + NH~4~]^+^ and [M + H]^+^ gave similar, abundant product ions and thus underwent the same types of fragmentation. This indicated that ammonium ions initially attached to brevetoxins forming [M + NH~4~]^+^ easily lose neutral ammonia in a first step in the gas phase, leaving protonated brevetoxin [M + H]^+^ to readily undergo further fragmentation under CID. Copyright © 2006 John Wiley & Sons, Ltd.