Preparation of acetazolamide composite microparticles by supercritical antisolvent techniques

The possibility of preparation of ophthalmic drug delivery systems using compressed anti-solvent technology was evaluated. and RL 100 were used as drug carriers, acetazolamide was the model drug processed. Compressed anti-solvent experiments were carried out as a semi-continuous or a batch operation from a liquid solution of polymer(s) + solute dissolved in acetone. Both techniques allowed the recovery of composite particles, but the semi-continuous operation yielded smaller and less aggregated populations than the batch operation. The release behaviour of acetazolamide from the prepared microparticles was studied and most products exhibited a slower release than the single drug. Moreover, the release could be controlled to some extent by varying the ratio of the two Eudragit used in the formulation and by selecting one or the other anti-solvent technique. Simple diffusion models satisfactorily described the release profiles. Composites specifically produced by semi-continuous technique have a drug release rate controlled by a diffusion mechanism, whereas for composites produced by the batch operation, the polymer swelling also contributes to the overall transport mechanism

Analyse en differe et en ligne de la matiere organique contenue dans les eaux potables par les chromatographies

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Recovery of oils from press cakes by CO2-based technology

In a context of a strong demand for vegetable oils, the development of new “green” processes is essential to provide methods that avoid the use of organic solvents, work at relatively low temperatures and preserve the quality of the final products. The supercritical fluid extraction (SFE) process meets these objectives. In this study, five meals (hemp, flax, sesame, poppy and walnut) were subjected to SFE at 45 °C and 250 bar in the presence of ethanol as co-solvent. Using this method, between 77 and 98% of the lipids present in the meal could be extracted. Except for poppy, 50% of the lipids present in the cake were recovered as a separate oily liquid phase. SFE was not selective toward certain types of triglycerides: the oils obtained exhibited the same fatty acid profile than the total lipid extracts from the cakes. In contrast, the composition in minor lipid components was dependent on the type of meal investigated. For example, hemp lipid extract was particularly rich in chlorophyll

Extraction of phospholipids from scallop by-product using supercritical CO2/alcohol mixtures

The objective was to produce phospholipid-enriched extracts from a new fishery by-product (scallop wastes) using supercritical fluid technology. A two-step fractionation scheme was used to improve the extraction selectivity by first deoiling the dried material by neat CO2 and secondly extracting phospholipids by CO2 plus ethanol. During this step, extracts were collected and quantified for their content in total lipids (by Folch extraction), phospholipids (by phosphorus nuclear magnetic resonance) and non-lipid components (by gravimetry). The influence of temperature (27-60 degrees C) and extracting fluid composition (15:85 to 50:50 w:w ethanol:CO2) on extraction kinetic and extract composition was analyzed. Propano1-2 was attempted as co-solvent as well. With ethanol, the highest content in phospholipids (58 g/100 g of extract) was obtained at 45 degrees C and 15 wt% of co-solvent, whereas propanol(-2) was far more selective and led to an extract with a purity of 90 g/100 g of extract in phospholipids in conditions of 27 degrees C and 50 wa of co-solvent. Compared to pure ethanol or conventional choroform:methanol extractions, CO2-based mixtures allowed for recovering extracts of phospholipids content higher than 35 g/100 g of lipids. Besides phosphatidylcholine, ether glycerophospholipids and phosphonolipids were detected in samples as well. (C) 2014 Elsevier Ltd. All rights reserved

Etude du mode de mise en contact de phases par jets d'impact appliqué aux procédés de génération de particules en milieu supercritique

L objectif de ce travail est d étudier l influence de jets d impact libres utilisés comme mode de mise en contact des phases dans les procédés de recristallisation utilisant un fluide supercritique comme anti-solvant. L influence des variations de plusieurs paramètres opératoires sur l hydrodynamique des jets et sur les caractéristiques des poudres de Sulfathiazole a été étudiée. Les paramètres sont la vitesse des jets (de 0,25 m.s-1 à 25,92 m,s-1), le rapport molaire solvant/CO2 (de 2,5 % à 20 %), la température (de 313 K à 343 K), la pression (10 MPa à 20 MPa) et la concentration du soluté dans la solution (de 0,5 % à 1,8 %). Les conditions de mélange ont été caractérisées par l estimation des puissances dissipées par les jets d impact, variant de 0,1 à 158 W.kg-1 dans les conditions étudiées. Les résultats ont montré que la vitesse des jets et la sursaturation sont deux paramètres-clés contrôlant la cristallisation avec un effet prépondérant de la sursaturation. Les cristaux obtenus ont des tailles, distributions de taille, faciès et nature polymorphique différents selon les conditions. La forme polymorphique la plus stable a été obtenue pure ou en mélange. Une comparaison avec le procédé SAS classique a montré que les particules sont significativement plus petites lorsqu elles sont cristallisées avec les jets d impact, ce qui confirme que ce dispositif créant un mélange plus intense, permet d accélérer la cinétique de nucléation.Ce travail devrait contribuer à une meilleure maîtrise des procédés de cristallisation en milieu supercritique.The aim of this work is to study the influence of free impinging jets used for the fluids introduction in supercritical anti-solvent (SAS) processes. The influence of the variations of several operating parameters upon jets hydrodynamics and upon the powder characteristics is studied. Parameters are jets velocity (0.25 m.s-1 to 25.92 m.s-1), molar ratio solvent / CO2 (2.5 % to 20 %), temperature (313 K to 343 K), pressure (10 MPa to 20 MPa) and solute concentration in the organic solution (0.5 % to 1.8 %). Mixing conditions have been characterized estimating the dissipated powers of the impinging jets, varying from 0,1 à 158 W.kg-1 in the studied conditions. The results showed that jets velocity and supersaturation are two key-parameters controlling the crystallization with a preponderant effect of supersaturation. The obtained crystals have different size, particle size distribution, habit and polymorphic nature depending on the conditions. The most stable polymorphic form has been obtained pure or in mixture.A comparison with the classical SAS process showed that mean particle sizes are significantly smaller with impinging jets device proving that this device, creating a more efficient mixing, enhances the nucleation kinetics.This work may contribute to a better control of processes of crystallization in supercritical media.AIX-MARSEILLE3-Bib. élec. (130559903) / SudocSudocFranceF

Recovery of oils from press cakes by CO

In a context of a strong demand for vegetable oils, the development of new “green” processes is essential to provide methods that avoid the use of organic solvents, work at relatively low temperatures and preserve the quality of the final products. The supercritical fluid extraction (SFE) process meets these objectives. In this study, five meals (hemp, flax, sesame, poppy and walnut) were subjected to SFE at 45 °C and 250 bar in the presence of ethanol as co-solvent. Using this method, between 77 and 98% of the lipids present in the meal could be extracted. Except for poppy, 50% of the lipids present in the cake were recovered as a separate oily liquid phase. SFE was not selective toward certain types of triglycerides: the oils obtained exhibited the same fatty acid profile than the total lipid extracts from the cakes. In contrast, the composition in minor lipid components was dependent on the type of meal investigated. For example, hemp lipid extract was particularly rich in chlorophyll

Numerical simulation of dripping and jetting in supercritical fluids/liquid micro coflows

In this work, a two dimensional simulation of segmented micro coflows of CO2 and water in microcapillaries (20 < T (°C) < 50 and 8 < p (MPa) < 16.5) was carried out using a combination of the one-fluid model and the volume of fluid (VOF) method to describe the two-phase flow and a penalty method to account for the wetting property of the capillary walls. The computational work was validated by comparing numerical and experimental results in both the dripping and jetting regimes. The agreement of the calculated pressure difference across the droplet or jet interface with the Laplace-Young's law was assessed as supplementary criteria. The effects of CO2/water interfacial tension (5 < σ (mN m−1) < 35) and wall wettability (contact angle CO2/wall varying from 0 to 180°) on the segmented water-supercritical CO2 microflows were specially described. It was shown that switching the wall surface from hydrophilic to hydrophobic by tuning the contact angle allows for changing the droplet curvature so that the continuous water phase eventually undergoes a phase inversion resulting in water droplets/slugs formation in a continuous CO2 phase

Recovery of phenolics from apple peels using CO2 + ethanol extraction: Kinetics and antioxidant activity of extracts

Subcritical extraction (SFE) of dry and ground Golden delicious peels (30g) was investigated at 25 MPa and 50 degrees C using CO2 and ethanol (96%) in 75:25 mol ratio. As for conventional ethanol or methanol/acetone/water extraction, nine phenolics were identified in SFE-extracts including the sugar-based phloridzin and quercetin derivatives. Extraction kinetics of the nine phenolics and of the global yield were monitored via collection of fractions that were also characterized for their antioxidant activity (ABTS antiradical activity). Kinetics showed a constant extraction rate up to 1.1 kg of fluid and a decreasing rate afterwards, but the matrix was not exhausted after 3 h of extraction. Besides the classical continuous flow protocol, SFE was performed by introducing static periods between the dynamic collect of fractions. Static periods did not yield significant improvement in the overall yield and in the individual yield of most phenolics. Increasing the matrix loading did not improve the recovery either. Conversely, extractions from 15 g provided the highest phenolics yield of 800 mg/100 g(dry) (peels). For extracts tested for antioxidant capacity (30 g loading), values up to 5-6 mg Equivalent Ascorbic Acid/g(extract) were obtained. Activities were positively correlated with phenolics concentration in fractions only for static conditions. (C) 2014 Elsevier B.V. All rights reserved

Investigations of pharmaceutical compounds co-crystallization for application to chiral resolution assisted by supercritical CO2

Co-crystalline products are becoming increasingly important in the pharmaceutical industry, due to the chirality, low water solubility and low bioavailability of most active pharmaceutical ingredients (API). Solids with a single crystalline phase composed of two entities (API + coformer COF) linked via non-covalent interactions are called co-crystals. The modification of the API crystal lattice through the incorporation of the COF enhances the physicochemical properties of the initial drug without altering its therapeutic purposes. Thus, understanding crystallization processes can help to obtain products with desired properties. The formation of metastable conglomerates by co-crystallization can be a solution for optical resolutionApport du CO2 dans le contrôle de phase cristallin

Impact of Hydro-Alcoholic Solvents on the Oil and Phenolics Extraction from Walnut (Juglans regia L.) Press-Cake and the Self-Emulsification of Extracts

The objective was to evaluate the performance of four hydro-alcoholic solvents to simultaneously extract oil and more polar molecules as phenolics, among others, to produce complex extracts that eventually could self-emulsify after solvent removal. Walnut press-cake was selected as the sourcing material. Extractions were performed as a semi-continuous operation up to a solvent-to-solid ratio of 28, with a fractional collection of the effluent. Among the solvents, labelled by their alcohol content EtOH 58, EtOH 86, iPro 60 and iPro 90 for ethanol (EtOH) and isopropanol (iPro), iPro 90 allowed to reach an oil extraction efficiency of 97% while the recovery for the other solvents was in the range of 30&ndash;40%. For both alcohols, the increase of the solvent hydration negatively influenced the oil extraction but positively increased the recovery of phenolics that reached 17.6 mg GAE/gcake when EtOH 58 was used. Several fractions contained enough surface-active material and oil to self-assemble as emulsions. IPro 90 and EtOH 86 showed better performances in the sense that most extracts were able to emulsify, though extraction kinetics pointed out differences. The most hydrated solvents behaved equally, with extraction yields in the same range and a similar but limited emulsifying capacity of only few fractions