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G. Ramer, K. Wieland, C. Wagner, W.H. Buchegger, M. Kraft, M. Vellekoop, B. Lendl:
"2D-CoS Time-Resolved Infrared Spectroscopy of Sugar HD-Exchange";
Poster: 2DCoS-6, Sonoma County. California; 09.06.2011 - 12.06.2011.

It is known that sugars influence the structure of the H-bond network of water and thereby change its physical properties, such as the freezing point and the glas temperature. This ability to influence the properties of water differs from sugar to sugar. One of the sugars strongly affecting water is trehalose, which is used as "anti-freeze" by tardigrades, bacteria, crustaceans and plants. Branca et al. [1] showed that trehalose forms longer lived and stronger H-bonds with water than other saccharides. To find differences in the frequency with which hydrogen bonds between sugars and water are formed, we took time-resolved mid-IR spectra of the mixing of aqueous sugar solutions and D2O. As a sugar forms hydrogen bonds with heavy water molecules, some of its alcoholic hydrogen atoms are exchanged for deuterium, the OH-bands become weaker, and at the same time, the corresponding OD-bands at lower wavenumbers increase in intensity.
The two well established techniques for collecting time-resolved infrared spectra, step-scan and rapid-scan IR spectroscopy, both need a reaction that can be triggered e.g. by a laser pulse and thus were not applicable to our problem. Instead we used a micro-fluidic mixing device, which we presented at ICAVS 5 [2]. In our micro-mixer the time-resolution is achieved by mixing the reagents at the entrance of a micro-fluidic channel and then measuring at defined points along the channel. Via the flow-rate of the reagents, a spatial distance to the entrance of the channel can be converted to a temporal distance to the start of the reaction.
However, since all bands of interest overlap, it is difficult to find differences just by looking at the collected time-resolved spectra. 2D-CoS allowed us to visualize the changing sugar bands and, via the asynchronous plot, to gain insight into the order in which hydrogen bonds between sugar and water were formed. To calculate the 2D Correlation Spectra we used ImageLab, a new chemometrics and spectroscopic imaging software developed at Vienna University of Technology. ImageLab offers the flexibility needed in the ever-changing field of chemometrics via its plug-in interface.
[1] Branca C, et al. Vibrational studies on disaccharide/H2O systems by inelastic neutron scattering, Raman, and IR spectroscopy. The Journal of Physical Chemistry B. 2003;107(6):1444-1451.
[2] Wagner C, et al. Evaluation of a four-layer lamination micro mixer used for time resolved FTIR spectroscopy on the low ms time scale. ICAVS V. 2009

2DCoS, HD-exchange, Trehalose, Maltose, microfluidic,