ISSN 2319-5347, ISI Impact Factor: 0.763

VOLUME 03 NO. 01 JANUARY 2015:

Title:         Submicron salicylic acid formation using rapid expansion supercritical solution (RESS): characterization and optimization of operative variables influence using the response surface methodology
Authors:   Le Thi Kim Phung, Nguyen Thi Ngoc Tuyet
Abstract: Rapid expansion of supercritical solution (RESS) is the most common method of pharmaceutical particle forming approaches using supercritical fluids. The RESS method is a technology which produces small solid products with a very narrow particle size distribution, organic solvent-free particles. This process is also simple and easy to control the operating parameters in comparison with the other methods based on supercritical techniques. Salicylic acid is micronized via the rapid expansion of the supercritical CO2solution (RESS) process. Experimental design was used to investigate the effect of extraction pressure (150-300bar), extraction temperature (45-600C), and pre-expansion temperature (75-1000C) on the size and morphology of the precipitated salicylic acid particles. Besides, the size and morphology effects of two conditions including RESS with co-solvent and RESS without cosolvent have been investigated. Particles were characterized using scanning electron microscopy (SEM), static light scattering (SLS), differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FTIR) and mass spectrometer (MS) for thermal and chemical structure analysis. The average size of the unprocessed salicylic acid particles was 22.73μm. After the process, depending on the experimental conditions, smaller particles were obtained, the smallest of which was 1.222μm. Response Surface Methodology was used for the optimization of the results and showed that the smallest particle size at pressure 150bar, temperature 60◦C and pre-expansion temperature 81.75◦C. The obtained results are average particle sizes L/D 0.184μm/0.09μm with co-solvent and 1.171μm/0.202μm decreased significantly compared to the initial particle size. The results of DSC, XRD, FTIR and MS illustrate that products of RESS process are not degenerated.

Keywords:   Salicylic Acid, Rapid Expansion Supercritical Solution (RESS), Particle Size
Pages:          88-94

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