2015, №3

сс. 4-15

A New Method for Measuring the Solubility of Slightly Soluble Substances in Supercritical Carbon Dioxide

2015, №3

сс. 4-15

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R.D. Oparin, E.A. Vorobyev, M.G. Kiselev

Key words: solubility, IR-spectroscopy, supercritical fluids

A self-consistent approach to the measurement of solubility of biologically active
compounds in supercritical (SC) media based on the infrared spectroscopy is exemplified
by paracetamol in supercritical CO2. According to this approach, the integrated extinction
coefficient for a chosen analytical spectral band is determined from additional
spectroscopic measurement of the compound under study dissolved in an inert solvent
at known concentrations in the considered range of the parameters of state (pressure
and temperature — p, T ). The values of solubility of the compound under study in the
SC medium are calculated based on the above obtained values of the extinction coefficient
and the analytical values of the integral intensity of the chosen spectral band for saturated
solutions in the p,T-range of interest. The method allows one to determine the solubility
with a high accuracy even if the measured values are as low as 10-4—10-1 mol.%.

doi:10.1134/S1990793116070149