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: Space-tested fluid flow concept advances infectious disease diagnoses

add to favorites email to friend print save as pdf

Related Stories

First radar vision for Copernicus

5 minutes ago

Launched on 3 April, ESA's Sentinel-1A satellite has already delivered its first radar images of Earth. They offer a tantalising glimpse of the kind of operational imagery that this new mission will provide ...

New approach needed to deal with increased flood risk

21 minutes ago

Considering the impacts of climate change on flood risk may not be effective unless current risk is managed better, according to new research from the University of Bristol published today in the Journal ...

Robotics goes micro-scale

25 minutes ago

(Phys.org) —The development of light-driven 'micro-robots' that can autonomously investigate and manipulate the nano-scale environment in a microscope comes a step closer, thanks to new research from the ...

Biologists help solve fungi mysteries

38 minutes ago

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

Recommended for you

User comments : 0

More news stories

Making graphene in your kitchen

Graphene has been touted as a wonder material—the world's thinnest substance, but super-strong. Now scientists say it is so easy to make you could produce some in your kitchen.