Characterization of ethyl chloroformate derivative of beta-methylamino-L-alanine.
Beta-methylamino-L-alanine (BMAA) is a neurotoxic amino acid that can be produced by cyanobacteria in aqueous environments. To analyze this compound by gas chromatography/mass spectrometry (GC/MS), BMAA must be derivatized to a nonpolar, volatile compound. This can be accomplished by reacting BMAA with ethyl chloroformate. While carrying out electron ionization (EI) mass spectrometric analysis on the (13)C-labeled derivative, it was discovered that the formation of an ion with a peak at m/z 245.12 is the result of [CH(3)CH(2)O.] loss from the amino groups resulting from alpha-cleavage. This differs from previous reports that attributed this peak to alpha-cleavage of the carboxylic ester portion of the BMAA derivative. This finding is important for understanding BMAA derivative mass spectrometric fragmentation patterns and ultimately to properly identifying and quantifying BMAA. Fragmentation pathways for the formation of other major peaks observed in the EI mass spectra are also proposed.
Guo
Tan
T
Wisconsin State Laboratory of Hygiene, University of Wisconsin at Madison, Madison, Wisconsin 53718, USA.
Geis
Steve
S
Hedman
Curtis
C
Arndt
Michael
M
Krick
William
W
Sonzogni
William
W
D000599:Amino Acids, Diamino / Q000737:chemistry*; D000087522:Cyanobacteria Toxins; D005563:Formic Acid Esters / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization
D000599:Amino Acids, Diamino; D000087522:Cyanobacteria Toxins; D005563:Formic Acid Esters; C007658:ethyl chloroformate; C001824:beta-N-methylamino-L-alanine