Hamburg 2009 – scientific programme

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MO: Fachverband Molekülphysik

MO 3: Biomoleküle 2

MO 3.2: Talk

Monday, March 2, 2009, 16:45–17:00, VMP 6 HS-F

Organic Molecules in Supercritical Fluids: Solubility and Shift of Phase Boundaries — •Adnan Sarfraz, Wolfgang Christen, and Klaus Rademann — Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin

The dissolution of organic molecules in supercritical fluids has manifold applications, e.g. in supercritical fluid chromatography and the formation of nano-sized particles. To facilitate the process of dissolution, co-solvents are employed frequently. The addition of co-solvents shifts the phase boundary of the mixture; in most cases this shift is estimated theoretically. The knowledge of the critical point of the mixture is important to fully utilize the solvating capabilities. Using a new setup we can determine the phase boundaries of pure and mixed substances experimentally. The basic idea is the increased scattering of light in the vicinity of the gas-liquid phase boundary. We report results on the shift of the critical point of ethylene on addition of ethanol. Furthermore, in a continuation of the previous work on mass spectrometric detection of nucleobases in expanded supercritical fluids, we report on the pressure dependence of their solubility in supercritical ethylene with ethanol as co-solvent.