Differentiating Oligosaccharide Isomers via Infrared Spectra of Gaseous Ions

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Prof. John Eyler and his group at the University of Florida are supported by the Analytical and Surface Chemistry Program to study the differentiation of structural isomers by mass spectrometry. These species have different chemical structures but identical mass, so they ordinarily cannot be distinguished by mass spectrometry. The Eyler group uses Fourier transform ion cyclotron resonance (FTICR) mass spectrometers and a number of different lasers to obtain the infrared spectra of isomeric ions in several wavelength regions using the technique of infrared multiple photon dissociation. Lasers used include a widely tunable free electron laser in The Netherlands and three lasers at the University of Florida - a continuously tunable optical parametric oscillator (OPO) laser and line tunable CO and CO2 lasers. Model analytes are carbohydrates and their product ions, a group of molecules having an immense number of stereoisomers. Spectral results are supplemented with theoretical calculations of infrared spectra, to determine which normal modes contribute to absorption bands. Data mining techniques enhance the ability to differentiate isomeric species.These activities serve to train new chemists, to attract new scientists via participation of undergraduates in research, and to develop methodology of general use for isomeric discrimination of molecules by mass spectrometry and valuable user facilities serving the international community. The undergraduate research experience involve an international component, as summer projects are carried out both at UF and at the free electron laser for infrared experiments (FELIX) facility in The Netherlands, in conjunction with a Partnerships for International Research and Education (PIRE) program which involves that facility.