Determination of Paclitaxel Solubility in Carbon Dioxide Using Quartz Crystal Microbalance

A quartz crystal microbalance (QCM) is used to determine the phase equilibrium of paclitaxel-carbon dioxide system in the pressure range of 0–11 MPa and at temperatures of 35 °C, 40 °C and 45 °C. The experimental results indicated that gaseous CO2 could be absorbed poorly into paclitaxel. The swelling of paclitaxel film in CO2 was observed before paclitaxel dissolved into supercritical carbon dioxide (ScCO2) with the increase of pressure. It was found that ScCO2 was not a good solvent for paclitaxel. The mole fraction of paclitaxel in ScCO2 was in the range of (4.5×10−9)–(7.8×10−9) under all our experimental conditions. Therefore, a much higher pressure than the CO2 supercritical point and/or a cosolvent must be used in any processes wherever paclitaxel dissolution in ScCO2 is required.