Measurement and modeling of solubilities of capsaicin in high-pressure CO2

Measurements on solid-fluid equilibrium were performed for capsaicin in sub- and supercritical carbon dioxide (CO2) at several temperatures (298, 308, 313 and 318 K) and over a pressure range from 6 to 40 MPa, to verify the operation of a new static-analytic set-up. This set-up consisted of a high-pressure static equilibrium cell coupled to a high-performance liquid chromatograph (HPLC). The new equilibrium data have been critically compared with available literature data; some differences were observed, especially at the two highest assayed temperatures. Experimental solubility values were correlated by using three different models, a density-based model, a cubic equation of state with quadratic mixing rules, and a group contribution equation of state. The density correlation results showed good agreement with the experimental data, in contrast to the results of both equations of state. (c) 2004 Elsevier B.V. All rights reserved.