(645f) Solubility Measurements of Anthracene to Supercritical Carbon Dioxide Using Both Variable-Volume View Cell with Ultra Low-Volume and HPLC Technique

Supercritical carbon dioxide (scCO2) technology has reached to a practical stage and variety of new substances has been employed in scCO2 systems. Appropriate solubility data are a crucial factor for scCO2 process design, so an efficient solubility measurement technique for such new substances is required. Reducing amount of sample for the measurement is important, because expensive, toxic or highly flammable reagents are included in such new substances. We have developed solubility measurement technique using high-performance liquid chromatography (HPLC) and variable volume view cell. In this work, we demonstrate a successful solubility measurement with quite small amount of substance using variable-volume view cell with ultra low-volume and HPLC technique.

Anthracene was selected as a model substance in this work. Details of the variable-volume view cell system with ultra low-volume are described in another paper of this conference (T. Furuya, et. al.). HPLC system was conducted by the same manner with our previous work (S. Yoda et. al., J. Supercritical Fluids, 44, 2008 139-147). Anthracene was dissolved in scCO2 at 313 K and 8-20 MPa. 2 micro liter of scCO2 solution was directly injected into the HPLC eluent (dichloromethane: methanol: hexane 45:45:10 v/v/v) and the concentration of anthracene was determined by UV-VIS detector.

Using the above measurement system, we have successfully obtained reasonable solubility profiles at 313K and 8-20 MPa (7 data points) using only 7.5 mg of anthracene. Relative standard deviation of the measurements was comparable to a reliable measurement with larger amount of sample. The proposed technique is promising for effective and precise solubility measurement of substances such as drugs, biomedical reagents, noble-metal complexes and explosives.