SFE of rosemary oil: Assessment of the influence of process variables and extract characterization

The effects of temperature and solvent density on the characteristics of the extracts obtained from supercritical fluid extraction (SFE) of the volatile compounds from Brazilian rosemary (Rosamarinus officianalis L., Labiatae) using carbon dioxide (CO₂) as solvent were investigated. The experiments were performed in a semi-batch laboratory scale home-made unit at two temperatures, viz. 310.15 and 320.15 K, over the pressure range of 100-160 bar. This study allowed to determine the crossover point and the maximum solubility of the oil. The products were analyzed by HRGC-MS, and compounds grouped in three different classes according to their molecular mass distribution in order to evaluate the influence of the variables studied on the characteristics of the extracts. The model proposed by Sovová was adopted in an attempt to interpret the mass transfer phenomena in the extraction process.     

Supercritical fluid extraction of oxindole alkaloids from Uncaria tormentosa

Supercritical fluid extraction of oxindole alkaloids from Uncaria Tormentosa is described. The extraction was performed with supercritical carbon dioxide alone and with supercritical carbon dioxide modified with 10% metanol, and the extracts were analyzed by GC/MS and HPLC/MS.     

Solubilities of lactic acid and 2-hydroxyhexanoic acid in supercritical CO2

Solubilities of lactic acid and 2-hydroxyhexanoic acid in supercritical CO₂ have been measured at T=(311 or 313, 318, 328 K) in the pressure range from 50 to 200 bar. The measurements have been performed using a flow-type apparatus. The solute solubility in compressed carbon dioxide increased with pressure at all investigated temperatures. At pressures below 130 bar, a solubility decrease on temperature increase was observed. An accurate correlation method for the solubility of low volatile substances in supercritical CO₂ has been applied for the interpolation of the experimental results.     

Supercritical Carbon Dioxide Extraction of Salidroside from Rhodiola rosea L var. rosea Root

Salidroside from the root of Rhodiola rosea L var. rosea was extracted by supercritical carbon dioxide with and without methanol as modifier. Three parameters, i.e. temperature, pressure and different concentrations of methanol were optimized. Salidroside determinations were carried out using high‐performance liquid chromatography (HPLC) with UV‐Vis detector. An experimental design of response surface methodology (RSM) was used to map the effect of pressure (at 200, 300 and 400 bar), temperature (at 50, 60 and 70 °C) and percentage of methanol modifier (at 80, 90 and 100%) on the extraction yield of the active compound and to determine the optimal conditions for the extraction of salidroside from the root of plant. The results showed that supercritical carbon dioxide failed to extract salidroside from the plant material without a methanol as modifier. The yield obtained after 1.5 h extraction with the rate of modifier 0.4 mL/min and 300 bar, 70 °C, and 80 percent of methanol modifier condition was the highest (17.15 mg/g). The optimum conditions were 70 °C, 295.49 bar and 80 percent of methanol as modifier with the yield of 16.17 mg/g. In addition, the yield obtained with supercritical fluid extraction (SFE) was compared with the Soxhlet extraction, whose yield was 8.64 mg/g.     

Supercritical extraction of phloroglucinol and benzophenone derivatives from Hypericum carinatum: quantification and mathematical modeling

The aerial parts of Hypericum carinatum (Guttiferae) were extracted with supercritical carbon dioxide under constant temperature (40, 50 or 60°C) and gradual pressure increase (90, 120, 150 and 200 bar) aiming at the recovery of enriched fractions containing uliginosin B, cariphenone A and cariphenone B, compounds of pharmaceutical interest. The yields of these substances were determined by high‐performance liquid chromatography and compared with those obtained with n‐hexane maceration. The supercritical‐fluid extraction showed higher selectivity than the conventional solvent extraction method. After defining 40°C and 90 bar as the best conditions to obtain the target compounds, a mathematical model was used for the extraction process and a good correlation was achieved with the experimental data.     

Effect of the pre-treatment of the samples on the natural substances extraction from Helianthus annuus L. using supercritical carbon dioxide

The extraction of bioactive compounds from sunflowers (Helianthus annuus L.) with supercritical carbon dioxide has been studied. The samples were treated in four different ways and the effects of two factors (pressure and temperature) were investigated at 100, 500 bar and 35, 50 °C. The best yields were obtained using a high temperature and a high pressure (50 °C and 500 bar). The dry samples produced better extraction yields than the moist samples. The bioactivities of the extracts were compared for the samples treated in different ways. The best activity profiles were obtained for the moist samples extracted at 35 °C and 500 bar.     

Supercritical fluid extraction of kava lactones from Piper methysticum (kava) herb

Supercritical fluid extraction of kava lactones from Piper methysticum Forst. herb is described here. The extraction was performed with supercritical carbon dioxide alone and supercritical carbon dioxide modified with 15% ethanol, and the extracts were analyzed by gas chromatography/mass spectrometry. Seven lactones including: 7,8-dihydrokavain; kavain; 5,6-dehydrokavain; 5, 6, 7, 8-tetrahydroyangonin; dihydromethysticin; yangonin; and methysticin were the major constituents in the SFE extract.     

The effect of pressure on the characteristics of supercritical carbon dioxide extracts from Calamintha nepeta subsp. nepeta

Chemists and industrialists are continuously attempting to develop greener and more environmentally benign chemical processes to extract essential oils and bioactive metabolites of high purity, finding various applications in cosmetics, detergents, nutraceuticals and pharmaceuticals. An increase preferenced for natural products over synthetic ones has made supercritical fluid technology a primary alternative for the generation of high-value bioactive ingredients. This effective technique requires only moderate temperatures, eliminates clean-up steps and avoids the use of harmful organic solvents. In this context, our study was focused on the chemical analysis of Calamintha nepeta subsp. nepeta aromatic extracts obtained with supercritical carbon dioxide. The effect of different operating conditions on the capacity of the lipophilic solvent to extract the targeted volatile components was also studied. The process was carried out at a fairly low constant temperature of 40°C, and with varying the pressure from 90 to 300 bar. The chemical composition of the extracts was analyzed by gas chromatography–mass spectroscopy. The results showed that the composition pattern, the concentrations of individual components and the quality of the extractable analytes were affected by pressure increase. The extraction yields varied from 0.73 to 1.21 wt% at 90 and 300 bar, respectively.     

Supercritical fluid extraction ofCymbopogon citratus (DC.) Stapf

Summary Cymbopogon citratus (DC.) Stapf. is also known as lemon grass; its leaves produce a volatile oil upon steam extraction which is used for medicinal purposes. This work describes the supercritical fluid extraction ofCymbopogon citratus in sequential and dynamic extraction modes. Different modifiers for supercritical carbon dioxide were used for the extractions. Principal compounds in the essential oils were analyzed by GC and GC-MS and identified as neral, geraniol, geranial, nerolic acid and geranic acid. Different chromatographic profiles were obtained when the type and proportion of modifier were changed.     

Solubility and micronisation of phenacetin in supercritical carbon dioxide

The rapid expansion of a supercritical solution (RESS) process represents an attractive prospect for producing sub-micron and nano-particles of medical compounds with low solubility. The solubility of phenacetin in supercritical carbon dioxide was measured by the analytical-isothermal method at pressures ranging from 9.0 MPa to 30.0 MPa and temperatures ranging from 308.0 K to 328.0 K. The results show that the mole fraction solubility of phenacetin in supercritical carbon dioxide is up to 10^?5. Four density-based semi-empirical models were introduced to correlate the experimental data. Agreement between the model predictions and experimental data is greater with the Adachi-Lu-modified Chrastil model than with the Chrastil model, Méndez-Santiago-Teja model, and the Bartle model and the average absolute relative deviation (AARD) observed is 0.0483. The preparation of fine phenacetin particles by the RESS process under different conditions of extraction temperatures (308.0–328.0 K), extraction pressures (9.0–30.0 MPa), nozzle temperatures (373.0–393.0 K), nozzle diameters (0.1–0.8 mm), and collection distance (20.0–40.0 mm) was investigated. The size and morphology of the resultant particles were analysed by SEM. A remarkable modification in size and morphology can be obtained by condition-optimisation.     

The phase behavior of fluorinated diols,divinyl adipate and a fluorinated polyester in supercritical carbon dioxide

The use of supercritical carbon dioxide as a reaction medium for polyester synthesis is hindered by the low solubility of diols in CO₂. However, it has been previously demonstrated that fluorinated compounds can exhibit greater miscibility with carbon dioxide than their hydrocarbon analogs. Therefore, the phase behavior of fluorinated diols and divinyl adipate (DVA), an activated diester, in supercritical carbon dioxide has been investigated at 323 K. The phase behavior of equimolar mixtures of DVA with the most carbon dioxide-soluble diol, 3,3,4,4,5,5,6,6-octafluorooctan-1,8-diol (OFOD), was also determined. The solubility of a polyester synthesized from DVA and 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD) was found to be less CO₂-soluble than its monomers. DVA was much more soluble in CO₂ than any of the fluorinated diols, therefore, no attempt was made to fluorinate the DVA structure. Because both substrates and polyester product were soluble in carbon dioxide, the enzymatic synthesis of a fluorinated polyester from DVA and octafluorooctandiol was performed in supercritical carbon dioxide, resulting in a polymer with a weight average molecular weight of 8232 Da.     

Comparative analysis of the oil and supercritical CO2 extract of Ridolfia segetum (L.) Moris

Supercritical carbon dioxide extraction allowed to obtain the volatile oil of different aerial parts of Ridolfia segetum (L.) Moris. Extraction conditions were as follows: pressure, 90 bar; temperature, 50°C and carbon dioxide flow, Φ?=?1.0?kg?h^?1. Waxes were entrapped in the first separator set at 90?bar and ?10°C. The oil was recovered in the second separator working at 15?bar and 10°C. The main components of the flower oil were α-phellandrene (19.4%), terpinolene (20.5%), piperitenone oxide (11.6%), β-phellandrene (8.2%), (Z)-β-ocimene (7.8%), myristicin (7.5%) and p-cymene (4.4%). The comparison with the hydrodistilled (HD) oil reveal that the significative difference was the content of sesquiterpenes which are higher in the supercritical fluid extraction (SFE) products. Collection of samples at different extraction times during supercritical extraction, allowed to monitor the change of the oil composition. Lighter compounds, as hydrocarbon monoterpenes, were extracted in shorter times than the heavier hydrocarbon and oxygenated sesquiterpenes. The oil from the steams was characterized by a high content of α-phellandrene (12.9%), terpinolene (11.6%), myristicin (11.0%), p-cymene (9.9%), β-phellandrene (8.2%) and (Z)-β-ocimene (6.0%) while the main components of the fruits were found to be myristicin (70.8%), piperitenone oxide (19.9%) and dill apiole (4.2%).     

Applications of a Technique for the HPLC Analysis of Liquid Carbon Dioxide Solutions

Abstract

A novel technique has been developed whereby substrate and solvent quantitation can be effected by means of reversed-phase high performance liquid chromatography. Carbon dioxide is detected by a differential refractometer.

Applications of this technique include the analysis of liquefied carbon dioxide-based aerosol mixtures, solubility measurements and liquid carbon dioxide extraction studies. Preliminary experiments suggest that this technique may also find application to the direct analysis of supercritical carbon dioxide extraction systems.     

超临界CO2在聚合物中的溶解计算研究进展

本文以超临界CO2在聚合物中的溶解计算模型为例,综述了状态方程、经验方程和人工神经网络计算方法的实现原理、研究现状和优缺点;依据人工神经网络预测方法存在的问题,重点阐述基于混合智能方法的神经网络溶解计算模型;并对溶解计算研究进行了总结和展望。     

Mathematical modelling for extraction of oil from Dracocephalum kotschyi seeds in supercritical carbon dioxide

Extraction of oil from Dracocephalum kotschyi Boiss seeds using supercritical carbon dioxide was designed using central composite design to evaluate the effect of various operating parameters including pressure, temperature, particle size and extraction time on the oil yield. Maximum extraction yield predicted from response surface method was 71.53% under the process conditions with pressure of 220 bar, temperature of 35 °C, particle diameter of 0.61 mm and extraction time of 130 min. Furthermore, broken and intact cells model was utilised to consider mass transfer kinetics of extracted natural materials. The results revealed that the model had a good agreement with the experimental data. The oil samples obtained via supercritical and solvent extraction methods were analysed by gas chromatography. The most abundant acid was linolenic acid. The results analysis showed that there was no significant difference between the fatty acid contents of the oils obtained by the supercritical and solvent extraction techniques.     

Theoretical and experimental study on Chloroquine drug solubility in supercritical carbon dioxide via the thermodynamic,multi-layer perceptron neural network (MLPNN), and molecular modeling

The design and development of supercritical carbon dioxide (sc-CO₂) based processes for production of pharmaceutical micro/nanoparticles is one of the interesting research topics of pharmaceutical industries owing to its attractive advantages. The solubility of drugs in sc-CO₂ at different temperatures and pressures is an essential parameter which should be determined for this purpose. Chloroquine as a traditional antirheumatic and antimalarial agent is approved as an effective drug for the treatment of Covid-19. Pishnamazi et al. (2021) measured the solubility of this drug in sc-CO₂ at the pressure range of 120–400 bar and temperature range of 308–338 K, and correlated the obtained data using some empirical models. In this work, a comprehensive computational approach was developed to more accurately study the supercritical solubility of Chloroquine. The thermodynamic models include two equations-of-state based models (Peng-Robinson and Soave-Redlich-Kowang) and two activity coefficient-based models (modified Wilson's and UNIQUAC)), as well as, a multi-layer perceptron neural network (MLPNN)) were used for this purpose. Also, molecular modeling was performed to study the electronic structure of Chloroquine and identify the potential centers of intermolecular interactions during the dissolution process. According to the obtained results, all of the theoretical models can predict Chloroquine solubility in sc-CO₂ with acceptable accuracy. Among these models, the MLPNN model possesses the highest precision with the lowest average absolute relative deviation (AARD%) of 1.76 % and the highest R_adj value of 0.999.     

Application of a gas-liquid entraining rotor to supercritical fluid extraction : Removal of iron(III) from water

Supercritical fluid extraction (SFE) of aqueous solutions is often limited by poor mass transport. The performance of a new gas-liquid entraining device was investigated to improve mass transport and thereby increase extraction efficiency. As a test system, iron(III) was extracted from water with a β-diketone chelating agent (HL) and supercritical fluid carbon dioxide. Metal β-diketonate complexes with sufficient solubility in supercritical fluid CO₂ are often poorly extracted from aqueous solutions due to limited mass transport between the water-soluble metal ion and the CO₂-soluble chelating agent. The new entraining device maximizes contact between the ligand-rich CO₂ phase and the metal ion-rich aqueous phase. Iron(III) was extracted from water with the chelating agent 2,2,7-trimethyl-3,5-octanedione (H(tod)) and supercritical fluid CO₂ at 60 °C and 20.8 MPa. With entrainment, 79% of the iron was removed from the aqueous phase. This represents a three-fold increase in iron extraction efficiency over that of a static system.     

Solubility of trans-Co2(CO)6 [3,5-bis(CF3)C6H3P(i-C3H7)2] in dense carbon dioxide

The title compound (1) was prepared by the reaction of 3,5-bis(CF₃)C₆H₃P(i-C₃H₇)₂ (L1) and Co₂(CO)₈. Its solubility in supercritical carbon dioxide was measured at varying temperatures and pressures using a modified analytical extraction device. Solubility data were determined in the temperature and pressure ranges between 40 and 70 °C and between 100 and 300 bar, respectively. The solubility of 1 is lower compared to (p-CF₃C₆H₄)₃P, but much higher than for transition metal complexes bearing phosphines without fluorinated substituents.     

The use of supercritical fluid extraction for the determination of 4-deoxynivalenol in grains: The effect of the sample clean-up and analytical methods on quantitative results

Summary Deoxynivalenol (DON) is one of the trichothecene mycotoxins produced byFusarium molds in grains. Polar cosolvents in supercritical carbon dioxide (SC-CO₂) are needed to extract and isolate the polar DON moiety. This unfortunately results in the extraction of many interfering compounds from the grains into the extracts obtained by supercritical fluid extraction (SFE). Analysis of DON by high performance liquid chromatography (HPLC) using ultraviolet detection (UV) does not provide a specific detection method, although specific detection of DON can be enhanced by using purification steps after SFE. Alternatively, combining SFE with an immunoaffinity method can improve detection specificity and sample cleanup. In this study, SFE was employed to determine DON in grains and cereal products. The effectiveness of the SFE method was compared with two different solvent extraction methods. The extracted DON was quantitatively determined by HPLC-UV using external standardization or competitive enzymelinked immunosorbent assay (ELISA). In some cases, extracts were purified prior to quantitative analysis of the DON by using solvent partitioning, and/or solid phase extraction, or immunoaffinity columns. Therefore, this paper describes the analysis of DON in cereals using different extraction, cleanup and analysis methods. Names are necessary to report factually on available data: however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the products to the exclusion of others that may also be suitable.     

Optimization of extraction of evodiamine and rutaecarpine from fruit of Evodia rutaecarpa using modified supercritical CO(2)

Evodiamine and rutaecarpine have been intensively studied due to their pharmacological actions and clinical applications. In this report, supercritical fluid was used to extract evodiamine and rutaecarpine from the unripe fruit of Evodia rutaecarpa. Response surface methodology using Box-Behnken experimental design was utilized to optimize parameters for supercritical carbon dioxide extraction with methanol as co-solvent. The effect of various values of dynamic extraction time (30-90min), temperature (50-70°C) and pressure (200-400bar) on extraction yields of the two compounds was evaluated. Determinations of the extracts were performed by high-performance liquid chromatography. The experimental data obtained were fitted to second-order polynomial equations and analyzed by analysis of variance. The highest yields predicted were 1.217mg/g for evodiamine and 0.969mg/g for rutaecarpine at the optimal values (time 78min, temperature 62°C, pressure 280bar and co-solvent flow rate 0.4mL/min), based on the selected range of experimental conditions.