Supercritical anti-solvent micronization of marigold-derived lutein dissolved in dichloromethane and ethanol

This work aims to study supercritical anti-solvent (SAS) micronization of lutein derived from marigold flowers. Lutein solution in dichloromethane (DCM) or ethanol was atomized into the stream of supercritical carbon dioxide (SC-CO₂) through a concentric nozzle in a pressurized vessel. The effects of pressure and SC-CO₂ flow rate on morphology, mean particle size (MPS) and particle size distribution (PSD) were investigated. The reduction in lutein MPS from 202.3 μm of unprocessed lutein to 1.58 μm and 902 nm could be achieved by SAS micronization using DCM and ethanol, respectively. In both solvent systems, no significant effects of pressure and SC-CO₂ flow rate on particle morphology were observed. However, pressure was found to have a significant effect on MPS and PSDs of lutein particles.     

Micronization of salicylic acid and taxol (paclitaxel) by rapid expansion of supercritical fluids (RESS)

The particle sizes of the pharmaceutical substances are important for their bioavailability. The bioavailability can be improved by reducing the particle size of the drug. In this study, salicylic acid and taxol were micronized by the rapid expansion of supercritical fluids (RESS). Supercritical CO₂ and CO₂ + ethanol mixture were used as solvent. Experiments were carried out to investigate the effect of extraction temperature (318–333 K) and pressure (15–25 MPa), pre-expansion temperature (353–413 K), expansion chamber temperature (273–293 K), spray distance (6–13 cm), co-solvent concentration (ethanol, 1, 2, 3, v/v, %) and nozzle configuration (capillary and orifice nozzle) on the size and morphology of the precipitated salicylic acid particles. For taxol, the effects of extraction pressure (25, 30, 35 MPa) and co-solvent concentration (ethanol, 2, 5, 7, v/v, %) were investigated. The characterization of the particles was determined by scanning electron microscopy (SEM), optical microscopy, and LC–MS analysis.The particle size of the original salicylic acid particles was L/D: 171/29–34/14 μm/μm. Depending upon the different experimental conditions, smaller particles (L/D: 15.73/4.06 μm/μm) were obtained. The particle size of taxol like white crystal powders was reduced from 0.6–17 μm to 0.3–1.7 μm The results showed that the size of the precipitated salicylic acid and taxol particles were smaller than that of original particles and RESS parameters affect the particle size.     

SFC–MS/MS for identification and simultaneous estimation of the isoniazid and pyrazinamide in its dosage form

An ecofriendly and sensitive SFC–MS/MS method (using TurboIonSpray probes) has been developed to measure Isonaizid (INH) and pyrazinamide (PYZ) in fix dosage combination (FDC) by dissolving in dichloromethane:methanol:formic acid (50:50:0.1 v/v/v). Supercritical carbon dioxide (SC-CO₂) is used as mobile phase at a flow rate of 2 ml/min and modifier used is dichloromethane:methanol:formic acid (50:50:0.1 v/v/v) at a flow rate of 0.3 ml/min. High penetration power, low viscosity, negligible toxicity makes the obvious choice for environment friendly mobile phase. The separation of INH and PYZ was achieved in less than 5 min using a C18 reverse-phase fused-core column (Inertsil ODS-5 μm C18, 150 mm × 4.6 mm). The method was validated as per international standards in terms of selectivity, linearity, precision and recovery. The method was found to be linear and % recovery was found to be 98.89–100.33% and 99.27–100.06% for INH and PYZ, respectively. Lower limits of detection and quantification could be achieved for INH was 11.87 ng/ml and 35.97 ng/ml, respectively, and for PYZ was 35.42 ng/ml and 107.36 ng/ml, respectively. The proposed method was applied to the marketed formulation of different manufacturers.     

Micronization and characterization of squid lecithin/polyethylene glycol composite using particles from gas saturated solutions (PGSS) process

Lecithin was isolated from squid viscera residues after supercritical carbon dioxide (SC-CO₂) extraction at 25 MPa and 45 °C. The particle formation of squid lecithin with biodegradable polymer, polyethylene glycol (PEG) was performed by PGSS using SC-CO₂ in a thermostatted stirred vessel. By applying different temperatures (40 and 50 °C) and pressures (20–30 MPa), conditions were optimized. Two nozzles of different diameters (250 and 300 μm) were used for PGSS and the reaction time was 1 h. The average diameter of the particles obtained by PGSS at different conditions was about 0.74–1.62 μm. The lowest average size of lecithin particle with PEG was found by the highest SC-CO₂ density conditions with the stirring speed of 400 rpm and nozzle size of 250 μm. The inclusion of lecithin in PEG was quantified by HPLC. Acid value and peroxide value was measured after micronization of lecithin.     

Preparation of itraconazole/HP-β-CD inclusion complexes using supercritical aerosol solvent extraction system and their dissolution characteristics

The purpose of this study was to investigate the feasibility of a supercritical fluid process, called aerosol solvent extraction system (ASES), for producing solid-state inclusion complexes of itraconazole (ITR) with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). ITR was complexed with HP-β-CD at temperatures of 35–55 °C, pressures of 83–140 bar, CO₂ densities of 0.498–0.801 g/cm³, and solution concentrations of 1–5% (w/v). The ASES-processed inclusion complex powders were observed to consist of agglomerates of very fine (100–500 nm) particles. From the experimental results of X-ray diffraction and differential scanning calorimetry, it was found that ITR intermolecularly interacted with the HP-β-CD cavity, resulting in the formation of inclusion complex. Furthermore, the ASES-processed ITR/HP-β-CD powders showed a significant enhancement in the ITR solubility (up to 753.6 μg/mL) in an aqueous medium of pH 1.2. The aqueous solubility of ITR increased with pressure at a constant temperature, and we could obtain a relatively high solubility of 341 μg/mL at 140 bar and 35 °C. In a solution concentration range of 1–5% (w/v), the solubility increased with decreasing concentration, yielding 289–407 μg/mL. When the molar ratio of ITR to HP-β-CD was varied from 1:1 to 1:3, the ITR solubility increased with HP-β-CD content, giving a value of 753.6 μg/mL for the 1:3 ratio. For the ASES-processed ITR/HP-β-CD powders, the percent dissolution of ITR also increased considerably and about 90% of ITR was dissolved within 5–10 min.     

Response surface optimization of Smyrnium cordifolium Boiss (SCB) oil extraction via supercritical carbon dioxide

In this study, the essential oil of aerial parts of a species of a plant called Smyrnium cordifolium Boiss (SCB) was extracted by supercritical CO₂. The essence was analyzed by the method of GC/MS. Design of experiments was carried out with response surface methodology by Minitab 16 software to optimize four operating variables of supercritical carbon dioxide (SC-CO₂) extraction (pressure, temperature, CO₂ flow rate and extraction dynamic time). This is the first report announcing optimization of the operation of supercritical extraction of SCB in laboratorial conditions. Optimizing process was done to achieve maximum yield extraction. Independent variables were dynamic time (t_d), pressure (P), temperature (T) and flow rate of SC-CO₂ (Q) in the range of 30–150 min, 10–30 MPa, 40–60 °C and 0.5–1.7 ml/min, respectively. The experimental optimal recovery of essential oil (0.8431, w/w%) was obtained at 13.43 MPa, 40 °C, 150 min (dynamic) and 1.7 ml/min (CO₂ flow rate).     

Supercritical carbon dioxide combined with high power ultrasound: An effective method for the pasteurization of coconut water

Industrially, thermal treatments are extensively used to inactivate microorganisms in foods. However, the demand for new pasteurization methods with reduced impact on the nutritional content and overall food quality is increasing. In this context, this study investigated and compared the effect of supercritical carbon dioxide (SC-CO₂) alone or in combination with high power ultrasound (HPU) on both the natural microbial flora (mesophilic, lactic acid bacteria and yeast and molds) of coconut water and the pathogenic Gram-negative bacteria Salmonella enterica inoculated in the product. Inactivation kinetics were obtained at 12 MPa, by means of batch apparatuses, at different times (from 1 up to 60 min) and temperature conditions (from 25 up to 45 °C). The synergistic effect of SC-CO₂ + HPU was evident and a higher microbial reduction was achieved compared to SC-CO₂ alone: at 12 MPa and 40 °C about 5 log reductions were achieved for natural microbial flora in about 15 min while about 30 min were needed for SC-CO₂ treatment. The storage study highlighted that SC-CO₂ treated coconut water resulted microbiologically unstable and showed heavy regrowth phenomena during the storage, while, a full shelf life of 4 weeks was assured for SC-CO₂ + HPU treated samples.     

Supercritical CO2 extraction of lutein esters from marigold (Tagetes erecta L.) enhanced by ultrasound

As a novel technique, supercritical CO₂ (SC-CO₂) extraction enhanced by ultrasound was applied to the extraction of lutein esters from marigold and the extraction curves were described by Sovová model. The mass transfer coefficient in the solid phase (k_s) increased from 3.1 × 10⁻⁹ to 4.3 × 10⁻⁹ m/s due to ultrasound. The effect of extraction parameters including particle size of matrix, temperature, pressure, flow rate of CO₂, and ultrasonic conditions consisting of power, frequency and irradiation time/interval on the yield of lutein esters were investigated with single factor experiments. The results showed that the yield of lutein esters increased significantly with the presence of ultrasound (p < 0.05). The maximal yield of lutein esters (690 mg/100 g) was obtained for a particle size fraction of 0.245–0.350 mm, extraction pressure of 32.5 MPa, temperature of 55 °C and CO₂ flow rate of 10 kg/h with ultrasonic power of 400 W, ultrasonic frequency of 25 kHz and ultrasonic irradiation time/interval of 6/9 s.     

Synthesis of titanium oxide particles in supercritical CO2: Effect of operational variables in the characteristics of the final product

A new chemical precursor is proposed for the synthesis of TiO₂ anatase nanoparticles in supercritical CO₂: the organometallic diisopropoxititanium bis(acetylacetonate) (DIPBAT). DIPBAT thermohydrolysis in supercritical carbon dioxide (SC-CO₂) has been studied in the range 10.0–20.0 MPa and 200–300 °C, and compared with that of titanium tetraisopropoxide (TTIP). The proposed reaction mechanism is a thermohydrolysis, where the hydrolysis of acetylacetonate groups is the limiting step of the reaction rate. The addition of water directly to the reaction favours the growth of formed particles, whereas ethanol offers better results as hydrolysing reactant, leading to smaller particles. Experiments have been performed first in a batch process and secondly in a semi-continuous one, varying the residence time in the reactor from 30 s to 2 min. The effect of operational variables in the final product and their influence in the different steps of the process have been studied. Results have shown that product crystallinity is related with temperature, and temperatures higher than 250 °C are necessary to obtain well-crystallized TiO₂ anatase. In the same sense, area Brunauer–Emmett–Teller (BET) is connected with crystallinity, and amorphous product, Ti(OH)₄, shows the highest surface area. Particle size and particle size distribution (PSD) are controlled by instantaneously supersaturation degree, and precursor concentration together with pressure are the main responsible of particle size control. Operational conditions influence solubility of species, mass transfer, chemical reaction and nucleation and particle growth and they mark the final characteristics of the product and its application. In such a way, good crystallized TiO₂ anatase particles of about 200 nm in diameter have been obtained working at 300 °C, 20.0 MPa and residence time of 2 min, with a reaction medium composed by CO₂/ethanol (80/20, v/v). Such particles present good optical properties and specific surface area BET of around 150 m²/g. At lower working temperatures the obtained particles present worse crystallinity; however, their specific surface area increases to 350 m²/g and they are suitable as support of metal clusters in heterogeneous catalysis.     

Characterization of wheat bran oil obtained by supercritical carbon dioxide and hexane extraction

Supercritical carbon dioxide (SC-CO₂) and soxhlet extraction using was carried out to extract oil from wheat bran oil. For SC-CO₂, the pressure and temperature were ranging from 10 to 30 MPa and 313.15–333.15 K. The extraction was performed in a semi batch process with a CO₂ flow rate of 26.81 g/min for 2 h. Wheat bran oil was characterized to investigate the quality. Acid value (AV) and peroxide value (POV) were higher in hexane extracted oil compared to SC-CO₂ extracted oil. Induction period was measured by rancimat test. The oil obtained by SC-CO₂ extraction had higher capability to delay the oxidation by surrounding environment. The DPPH radical scavenging activity was also measured. The SC-CO₂ extracted oil showed higher radical scavenging activity compared to hexane extracted oil.     

Response surface optimization of supercritical CO2 extraction of α-tocopherol from gel and skin of Aloe vera and almond leaves

Supercritical fluid extraction (SFE) was studied as an alternative technology in the pharmaceutical industry for the separation of α-tocopherol from gel and skin of Aloe vera and almond leaves. The influence of operating conditions was investigated on the recovery of supercritical carbon dioxide (SC-CO₂) extraction of α-tocopherol from three-year old Aloe vera (Aloe barbadensis Miller) leaf gel. The obtained results were compared with the conventional Soxhlet extraction. Response surface methodology (RSM) was applied to optimize effective variables on the extracted recovery of α-tocopherol. The maximum α-tocopherol recovery of 53.41% from Aloe vera gel was obtained with employing RSM predicted optimal operating conditions of 32 MPa, 45.91 °C, 0.84 ml SC-CO₂/min and 140 min for extraction. The α-tocopherol extraction yield for gel and skin of Aloe vera and almond leaves at these optimal operating conditions were obtained 1.53, 16.29 and 2.61 mg/100 g dry sample, respectively.     

Micronization of ketoprofen by the rapid expansion of supercritical solution process

The particle size of the pharmaceutical substances is important for their bioavailability (the percentage of the drug absorbed compared to its initial dosage). The absorption rate can be increased by reducing particle size of the drug particles. This study was conducted to investigate the effects of the extraction pressure (140–220 bar), extraction temperature (308–338 K), nozzle length (2–15 mm), effective nozzle diameter (450–1700 μm), and collection distance (1–10 cm) on the size and morphology of the precipitated ketoprofen particles. The characterization (size and morphology) of the particles was investigated using scanning electron microscopy (SEM). The average particle size of the original material was 115.42 μm, while the average particle size of the micronized particles is between 0.35 and 7.03 μm near to quisi-spherical, needle and irregular shape depending upon the experimental conditions.     

Digestive enzymes characterization of krill (Euphausia superba) residues deoiled by supercritical carbon dioxide and organic solvents

In this study, Enzyme activities of krill were characterized before and after lipid extraction by supercritical carbon dioxide (SC-CO₂) and organic solvent, n-hexane and acetone. Krill SC-CO₂ extraction was performed under the conditions of temperature range from 35 to 45 °C and pressure, 150–250 bar for 2.5 h with a constant flow rate of 22 g/min. Extraction yields of lipids increased with pressure and temperature. The digestive enzyme activities of protease, lipase and amylase of SC-CO₂ treated krill residues were slightly decreased comparing to organic solvent, n-hexane and acetone treated residues. In SC-CO₂ treated samples, all of the digestive enzymes showed slightly higher temperature stability. In the other hand the crude extracts of SC-CO₂ and n-hexane treated krill samples showed almost same optimum pH and pH stability for each of the digestive enzymes. It was also found in SDS-PAGE that there are no significant differences in protein patterns of the crude extracts of untreated, SC-CO₂, n-hexane and acetone treated krill indicating no denaturation of proteins.     

Water and ethanol as co-solvent in supercritical fluid extraction of proanthocyanidins from grape marc: A comparison and a proposal

Supercritical carbon dioxide (SC-CO₂) extraction of grape marc was studied using water (W) and ethanol (EtOH) as co-solvent at 15% (w/w), 100 and 200 MPa, and 313.15, 323.15 and 333.15 K to analyze their influence upon total phenols of the extracts. The overall extraction curves were determined and suggested 10 MPa and 313.15 K as the best operating conditions for SC-CO₂ + 15%W extraction, and 10 MPa and 333.15 K for SC-CO₂ + 15% EtOH. The phenolic yields obtained were 63.4 g/kg of extract for SC-CO₂ + 15% W and 38.8 g/kg of extract for SC-CO₂ + 15% EtOH. An alternative method combining Sc-CO₂ + 15% W extraction, followed by SC-CO₂ + 15% EtOH was tested. This procedure provided the best results allowing to obtain the highest phenolic yield (68.0 g/kg of extract), phenol content (733.6 mg GAE/100 g DM), proanthocyanidins concentration (572.8 mg catechin/100 g DM) and antioxidant activity (2649.6 mg α-tocopherol/100 g DM). SC-CO₂ methods were compared with methanol extraction.     

Optimization of supercritical fluid extraction of phytosterol from roselle seeds with a central composite design model

Recovery of phytosterol from roselle (Hibiscus sabdariffa L.) seeds via supercritical carbon dioxide extraction modified with ethanol was investigated at pressures of 200–400 bar, temperatures from 40 to 80 °C and at supercritical fluid flow rates from 10 to 20 ml/min. It was found that an entrainer such as ethanol could enhance the solubility and extraction yield of roselle seed oil from the seed matrix, compared to values obtained using supercritical CO₂. After a typical run (holding period of 30 min, continuous flow extraction of 3 h), the results indicate that the oil recovery was optimal with a recovery of 108.74% and a phytosterol composition of 7262.80 mg kg^?1 at relatively low temperature of 40 °C, a high pressure of 400 bar and at a high supercritical fluid flow rate of 20 ml/min in the presence of 2 ml/min EtOH as entrainer. The solubility of roselle seed oil increased with temperature at the operating pressures of 200, 300 and 400 bar. Supercritical fluid extraction involved a short extraction time and the minimal usage of small amounts of entrainer in the CO₂.     

Formation and stabilization of submicron particles via rapid expansion processes

Submicron particles were produced by rapid expansion of supercritical solution into air (RESS) or an aqueous surfactant solution (RESSAS) to minimize particle growth and to prevent particle agglomeration. Thereby the effect of process conditions on the size of the particles precipitated was investigated. The obtained product was evaluated by measuring particle size by 3-wavelength extinction measurements, dynamic light scattering, specific surface areas by nitrogen gas adsorption, melting behaviour by differential scanning calorimetry, particle morphology by X-ray diffraction, scanning electron micrographs (SEM), and drug loading by high performance liquid chromatography.Prior to the particle formation experiments, the melting temperature of Salicylic acid under CO₂ pressure and the solubility of Salicylic acid in CO₂ were measured. The size of Salicylic acid particles produced via RESS decreased from 230 to 130 nm as the pre-expansion temperature decreased from 388 to 328 K and the specific surface area of the micronized particles was found to be up to 60 times higher than that of the unprocessed material. RESSAS experiments demonstrate that in 1 wt.% Tween 80 solutions Salicylic acid concentrations of 4.6 g/dm³ could be stabilized with particle diameters in the range of 180 nm. Additional experiments show that Ibuprofen nanoparticles with an average size of 80 nm and a drug concentration of 2.4 g/dm³ could be stabilized in 1 wt.% Tween^® 80 solutions. The use of a SDS solution instead of Tween^® 80 results in a stable aqueous suspension of phytosterol nanoparticles, where the average particle size is 50 nm at a drug concentration of 5.6 g/dm³.     

Ethanol modified supercritical carbon dioxide extraction of flavonoids from Momordica charantia L. and its antioxidant activity

Ethanol modified supercritical carbon dioxide (SC-CO₂) extraction of flavonoids from Momordica charantia L. fruits and its antioxidant activity were performed. The influences of parameters such as temperature, extraction time and pressure on the yield of flavonoids were investigated. The antioxidant activities of flavonoids were assessed by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and β-carotene bleaching test. The experimental data obtained indicated that pressure, temperature and time had significant effect on the extraction yield. The optimum extraction conditions, determined by the 3D response surface and contour plots derived from the mathematical models, were as follows: extraction temperature 46 °C, pressure 33.4 MPa, and extraction time 53.2 min. Under these conditions, the experimental value was 15.47 mg/g, which was well matched with value predicted by the model. The antioxidant activity of flavonoids obtained by ethanol modified SC-CO₂ extraction method had higher antioxidant activity than the flavonoids extracted by conventional solvent extraction (CSE) method. The DPPH radical-scavenging ability of flavonoids obtained by ethanol modified SC-CO₂ extraction method reached to 96.14 ± 1.02%, equivalent to the clearance rate of ascorbic acid at 1.2 mg/mL. Results indicated that ethanol modified SC-CO₂ extraction was a suitable approach for the selective extraction of flavonoids from M. charantia L.     

Extraction of protocatechuic acid from Scutellaria barbata D. Don using supercritical carbon dioxide

The use of supercritical carbon dioxide (SC⿿CO₂), with water as a modifier, was evaluated in this study as a method to extract protocatechuic acid (PA) from Scutellaria barbata D. Don. The highest extraction yield of PA, 64.094 ± 2.756 μg/g of dry plant, was achieved at 75 °C and 27.5 MPa, with the addition of 15.6% (v/v) water as a modifier. The mean particle size was 0.355 mm, the CO₂ flow rate was 2.2 mL/min (STP) and the dynamic extraction time was 100 min. At pressures of 16.2⿿30.0 MPa and temperatures of 45⿿75 °C, the mole fraction solubilities of PA in SC⿿CO₂ ranged from 2.829 ÿ 10^⿿7 to 9.631 ÿ 10^⿿7. The solubility data for PA fit well in the Chrastil model. It is evident that the SC⿿CO₂ extraction uses less solvent, saves both energy and time and is an environmentally friendly extract technology that can be used in the food, cosmetic and pharmaceutical industries.     

Generation and precipitation of paclitaxel nanoparticles in basil seed mucilage via combination of supercritical gas antisolvent and phase inversion techniques

In recent years, plant derived polymers have evoked tremendous interest in the field of drug delivery. In this work, a promising anticancer drug, paclitaxel, was precipitated in the basil seeds mucilage (BSM) using supercritical carbon dioxide (SC-CO₂). The employed SC-CO₂ process in this research is a combination of gas antisolvent and phase inversion techniques and consists of two steps: (1) casting solution preparation, a uniform mixture of BSM, water, paclitaxel and dimethyl sulfoxide (DMSO), (2) simultaneous generation and precipitation of nanoparticles in BSM structure using SC-CO₂ as antisolvent. The effect of DMSO/water ratio (4 and 6 (v/v)), pressure (10–16 MPa) and CO₂ addition rate (1–3 mL/min) on mean particle size (MPS), particle size distribution (PSD) and drug loading efficiency (DLE) were studied. Particle analyses were performed by scanning electron microscopy (SEM) and Zetasizer. High performance liquid chromatography was utilized for studying DLE. Nanoparticles of paclitaxel (MPS of 117–200 nm depending on process variables) with narrow PSD were successfully precipitated in BSM structure with DLE of 56.8–78.2%. The FTIR spectra confirmed that paclitaxel actually precipitated in basil seeds mucilage. Experimental results indicated that higher DMSO/water ratio, pressure and CO₂ addition decreased MPS and DLE.     

Modeling the inactivation of Staphylococcus aureus and Serratia marcescens in clinical solid waste using supercritical fluid carbon dioxide

The aim of the present study was to determine an effective sterilization method for safe handling and recycle-reuse of clinical solid waste materials. Supercritical fluid carbon dioxide (SC-CO₂) was applied in the inactivation of gram positive Staphylococcus aureus (S. aureus) and gram negative Serratia marcencens (S. marcescens) in clinical solid waste. The colony forming activity of the bacteria was completely lost at pressures 10–40 MPa, temperatures 35–80 °C and treatment period between 5 and 120 min. An increase in pressure at constant temperature and vice versa with the increasing treatment time enhanced the SC-CO₂ inactivation efficiency. The inactivation process was illustrated by the modified Gompertz equation. The SC-CO₂ inactivation of bacteria was compared with the steam autoclaved bacteria. Regrowth of the bacteria was observed in the autoclaved sample while no re-growth was detected in the SC-CO₂ treated clinical solid waste. Results from SEM image analysis, cellular protein and enzymatic activity of untreated, autoclaved and SC-CO₂ treated S. marcescens and S. aureus cells confirmed that SC-CO₂ is an effective sterilization method.