Isothermal titration calorimetry as a tool to determine the thermodynamics of demicellization processes.

Anne Kessler, Benjamin Zeeb, Bertolt Kranz, Orquídea Menéndez-Aguirre, Lutz Fischer, Jörg Hinrichs, Jochen Weiss

Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany.

The Review of scientific instruments 2012 Oct

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Demicellization of a 90 mM sodium dodecyl sulfate (SDS) solution in water at 10, 22, and 30 °C was studied by isothermal titration calorimetry (ITC). ΔH of the demicellization process was strongly temperature dependent, having an exothermic progression (-20.4 ± 0.9 kJ∕mol, max) at 10 °C and an endothermic one (3.7 ± 1.2 kJ∕mol, max) at 30 °C. ΔH for micelle dilution followed a slightly endothermic progression (0.9 ± 0.5 kJ∕mol at 30 °C, 0.7 ± 1.3 kJ∕mol at 22 °C, and 0.0 ± 0.5 kJ∕mol at 10 °C) at all studied temperatures. No differences in ΔH for micelle dilution and demicellization was observed at 22 °C. The temperature dependence of ΔH measured by ITC could be related to hydrophobic interactions. Therefore, ITC was shown to be a useful tool to describe the thermodynamics of demicellization processes and in addition to determine alterations in ΔH caused by changes in hydrophobic and steric∕electrostatic interactions.

Citation

Anne Kessler, Benjamin Zeeb, Bertolt Kranz, Orquídea Menéndez-Aguirre, Lutz Fischer, Jörg Hinrichs, Jochen Weiss. Isothermal titration calorimetry as a tool to determine the thermodynamics of demicellization processes. The Review of scientific instruments. 2012 Oct;83(10):105104