Researchers provide new information about mass spectrometry

Oct 15, 2007

Fresh data on mass spectrometry are presented in the report ‘Low-energy collision-induced fragmentation of negative ions derived from ortho-, meta-, and para-hydroxyphenyl carbaldehydes, ketones, and related compounds,’ produced by Professor Athula Attygalle and his colleagues in the Center for Mass Spectrometry at Stevens Institute of Technology.

According to a study, “Collision-induced dissociation (CID) mass spectra of anions derived from several hydroxyphenyl carbaldehydes and ketones were recorded and mechanistically rationalized. For example, the spectrum of m/z 121 ion of deprotonated ortho-hydroxybenzaldehyde shows an intense peak at m/z 93 for a loss of carbon monoxide attributable to an ortho-effect mediated by a charge-directed heterolytic fragmentation mechanism.”

“In contrast, the m/z 121 ion derived from meta and para isomers undergoes a charge-remote homolytic cleavage to eliminate an *H and form a distonic anion radical, which eventually loses CO to produce a peak at m/z 92. In fact, for the para isomer, this two-step homolytic mechanism is the most dominant fragmentation pathway. The spectrum of the meta isomer on the other hand, shows two predominant peaks at m/z 92 and 93 representing both homolytic and heterolytic fragmentations, respectively. (18)O-isotope-labeling studies confirmed that the oxygen in the CO molecule that is eliminated from the anion of meta-hydroxybenzaldehyde originates from either the aldehydic or the phenolic group. In contrast, anions of ortho-hydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde, both of which show two consecutive CO eliminations, specifically lose the carbonyl oxygen first, followed by that of the phenolic group. Anions from 2-hydroxyphenyl alkyl ketones lose a ketene by a hydrogen transfer predominantly from the alpha position. Interestingly, a very significant charge-remote 1,4-elimination of a H(2) molecule was observed from the anion derived from 2,4-dihydroxybenzaldehyde,” wrote Attygalle and his colleagues from Stevens.

The researchers concluded: “For this mechanism to operate, a labile hydrogen atom should be available on the hydroxyl group adjacent to the carbaldehyde functionality.”

Attygalle and colleagues published the results of their research in the Journal of Mass Spectrometry (Low-energy collision-induced fragmentation of negative ions derived from ortho-, meta-, and para-hydroxyphenyl carbaldehydes, ketones, and related compounds.

Citation: Journal of Mass Spectrometry, 2007; 42(9):1207-17).

Source: Stevens Institute of Technology

Explore further: Researchers engineer E. coli to produce new forms of popular antibiotic

Related Stories

Say Freeze: Photogs do 365-gigapixel sweep of Mont Blanc

3 minutes ago

Mont Blanc is the highest mountain in the Alps and has taken on an added distinction as the subject of the world's largest photograph. The Telegraph reported Monday that a photography team accomplished a worl ...

Blueprint for a thirsty world from Down Under

2 hours ago

The Millennium Drought in southeastern Australia forced Greater Melbourne, a city of 4.3 million people, to successfully implement innovations that hold critical lessons for water-stressed regions around the world, according ...

Recommended for you

Chemical deterrent from snow fleas identified

5 hours ago

Snow fleas keep predators at bay with a chemical deterrent. German scientists have now isolated this compound and identified it by means of spectroscopic analysis and X-ray crystallography. In the journal ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.