Enhancing methyldopa solubility via green supercritical fluid techniques using ethanol co-solvent.

Area of Science:

• Chemical Engineering
• Pharmaceutical Sciences
• Physical Chemistry

Background:

• Methyldopa is a crucial antihypertensive medication.
• Supercritical carbon dioxide (scCO2) offers a tunable and environmentally friendly solvent system.
• Understanding methyldopa solubility in scCO2 is vital for developing advanced drug delivery and purification methods.

Purpose of the Study:

• To investigate the solubility of methyldopa in supercritical carbon dioxide.
• To evaluate the effect of ethanol as a co-solvent on methyldopa solubility.
• To model and correlate the experimental solubility data using various thermodynamic approaches.

Main Methods:

• Experimental determination of methyldopa solubility in scCO2 at temperatures ranging from 308 K to 338 K.
• Inclusion of ethanol as a co-solvent at varying concentrations (1 and 3 mol %).
• Application of semi-empirical, empirical, and Peng-Robinson models for data analysis.

Main Results:

• Methyldopa solubility in scCO2 ranged from 0.078 × 10⁻⁴ to 1.082 × 10⁻⁴.
• Ethanol significantly enhanced methyldopa solubility, with a maximum increase of 15.70 times at 12 MPa and 338 K.
• The Soltani-Mazloumi model demonstrated the highest correlation with experimental solubility data.

Conclusions:

• Supercritical carbon dioxide with ethanol is an effective solvent system for enhancing methyldopa solubility.
• Thermodynamic modeling provides reliable predictions for methyldopa solubility in scCO2.
• These findings support the potential application of scCO2 for methyldopa processing and formulation.