3th WCSET-2014 at Nepal
Special Session at Ho Chi Minh City University of Technology, Vietnam:
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:
692-698