Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Analytical Chemistry

Mass Spec Ion Structure Controlled By Solvent Effects

August 11, 2008 | A version of this story appeared in Volume 86, Issue 32

ANION ID
[+]Enlarge
Tyrosine carboxylate (left) and tyrosine phenoxide (right) anions can be distinguished by new ESI MS technique.
Tyrosine carboxylate (left) and tyrosine phenoxide (right) anions can be distinguished by new ESI MS technique.

By employing different solvent systems, Zhixin Tian and Steven R. Kass of the University of Minnesota, Minneapolis, used electrospray ionization (ESI) mass spectrometry to selectively form and analyze two ionic structures of tyrosine (J. Am. Chem. Soc., DOI: 10.1021/ja802088u). The advance could point the way to performing similar chemical analyses on more complex biomolecules, such as proteins. ESI transports molecules of interest from solution to the gas phase for MS analysis. Many biomolecules can be ionized at different sites, and sometimes the most stable ions in the liquid and gas phases are different, Kass says. For researchers who are attempting to identify protein fragments or study biomolecule reactivity by MS, it’s important to know whether ESI produces the gas-phase or the liquid-phase structure. The Minnesota team used trimethylsilyl azide to derivatize tyrosine carboxylate, which is the most stable ion in solution, and tyrosine phenoxide, which is the most stable ion in the gas phase. They analyzed the MS fragmentation patterns to differentiate between the two anions, which have the same mass. By using methanol/water or acetonitrile solvent systems, the researchers controlled the relative amounts of carboxylate and phenoxide anions they observed.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.