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Published September 8, 2005 | metadata_only
Journal Article

Electrospray Ionization Ion Mobility Spectrometry of Carboxylate Anions: Ion Mobilities and a Mass−Mobility Correlation


A number of carboxylate anions spanning a mass range of 87−253 amu (pyruvate, oxalate, malonate, maleate, succinate, malate, tartarate, glutarate, adipate, phthalate, citrate, gluconate, 1,2,4-benzenetricarboxylate, and 1,2,4,5-benzenetetracarboxylate) were investigated using electrospray ionization ion mobility spectrometry. Measured ion mobilities demonstrated a high correlation between mass and mobility in both N_2 and CO_2 drift gases. Such a strong mass−mobility correlation among structurally dissimilar ions suggests that the carboxylate functional group that these ions have in common is the source of the correlation. Computational analysis was performed to determine the most stable conformation of the studied carboxylate anions in the gas phase under the current experimental conditions. This analysis indicated that the most stable conformations for multicarboxylate anions included intramolecular hydrogen-bonded ring structures formed between the carboxylate group and the neutral carboxyl group. The carboxylate anions that form ring confirmations generally show higher ion mobility values than those that form extended conformations. This is the first observation of intramolecular hydrogen-bonded ring conformation of carboxylate anions in the gas phase at atmospheric pressure.

Additional Information

© 2005 American Chemical Society. Received 11 March 2005. Published online 11 August 2005. Published in print 1 September 2005. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA) and at the Noyes Laboratory of Chemical Physics, California Institute of Technology. Financial support through NASA's Astrobiology Science and Technology Instrument Development, Planetary Instrument Definition and Development, and Mars Instrument Development programs is gratefully acknowledged. We appreciate critical discussion of Beauchamp group members, Heather A. Cox, Ronald L. Grimm, and Robert Hodyss through the whole research, and the support provided by the Mass Spectrometry Resource Center in the Beckman Institute. We also appreciate advice and discussion of Dr. Seung Soon Jang at the Materials Process Simulation Center, California Institute of Technology.

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August 19, 2023
August 19, 2023