Orthogonal array design for the optimization of supercritical fluid extraction of baicalin from roots of Scutellaria baicalensis Georgi

Supercritical fluid was used to extract baicalin from the roots of Scutellaria baicalensis Georgi. An orthogonal array design (OAD), OA(9)(3(4)), was employed as a chemometric method for the optimization of the supercritical fluid extraction of baicalin from the herbal medicine. Four parameters, namely, modifiers, temperature and pressure of supercritical fluid, and the dynamic extraction time, were studied and optimized by a three-level OAD in which the interactions between the parameters were neglected. Determinations of the extracts were performed by high-performance liquid chromatography. The effects of parameters were studied using analysis of variance. The results showed that selection of the modifier was the main factor in attaining higher yields of baicalin. While the other three factors had some effect on the extraction of the compound, the effect was much less than that of the modifiers. 1,2-Propanediol-modified supercritical fluid was more effective than 95% ethanol-modified supercritical carbon dioxide or methanol-modified supercritical carbon dioxide for the extraction of baicalin from the solid matrix. Finally, experimental conditions were proposed which can provide the highest extraction yield with respect to the considered factors.     

Supercritical fluid extraction of catechins from Cratoxylum prunifolium dyer and subsequent purification by high-speed counter-current chromatography

Supercritical fluid extraction of tea catechins including epigallocatechin-3-O-gallate (EGCG) and epicatechin-3-O-gallate (ECG) from Cratoxylum prunifolium Dyer was performed. The optimization of parameters was carried out using an analytical-scale supercritical fluid extraction (SFE) system designed in our laboratory. Then the extraction was scaled up by 100 times using a preparative SFE system under a set of optimized conditions of 40 degrees C, 25 MPa and modified CO2 with 80% ethanol aqueous solution. The combined yield of EGCG and ECG reached about 1 mg per 1 g of tea leaves where the solubility was near 1.4 x 10(-4) mass fraction of CO2 fluid. EGCG and ECG of high purity (>98%) were obtained from the crude preparative extract by high-speed counter-current chromatography.     

Identification of volatile compounds of Atractylode lancea Rhizoma using supercritical fluid extraction and GC–MS

Supercritical fluid was used to extract volatile components from the rhizoma of Atractylode lancea (A. lancea). An orthogonal array design (OAD), L₉ (3)⁴, was employed as a chemometric method for the optimization of the supercritical fluid extraction (SFE) of volatile compounds from the herbal medicine. Four parameters, namely, pressure, temperature, dynamic extraction time, and flow rate of CO₂, were studied and optimized by a three‐level OAD in which the interactions between the parameters were neglected. These compounds were identified according to their retention times and mass spectra by GC–MS. A total of 30 compounds of SFE extracts were identified. Atractylon (8.63%), hinesol (1.44%), β‐eudesmol (6.64%), elemol (0.42%), and atractydin (13.92%) were the major sesquiterpenes identified in A. lancea SFE extracts.     

Supercritical fluid extraction of cynaropicrin and 20-hydroxyecdysone from Leuzea carthamoides DC

Leuzea carthamoides is an adaptogenic plant containing biologically active compounds as ecdysteroids and guaianolide-type sesquiterpene lactones, conventionally extracted from the plant with ethanol. It may be a potential source of the mentioned natural compounds. Ethanol-modified near-critical CO(2) was used as selective solvent with the aim to increase the level of 20-hydroxyecdysone in the extract from L. carthamoides roots and to remove selectively cynaropicrin, a sesquiterpene lactone of bitter taste, from the leaves. The extraction conditions were varied (pressure 20-28 MPa, temperature 40-60 degrees C, ethanol concentration in the solvent 0-7.1%) and the extraction yield and extract composition were compared with the results of ethanolic extraction. The supercritical fluid extraction (SFE) from finely powdered plant was controlled by phase equilibrium. Cynaropicrin was quantitatively removed from the leaves where 89% of 20-hydroxyecdysone was retained. The extraction yield of 20-hydroxyecdysone from roots with ethanol-modified CO(2 )was lower by 30% than with ethanol but its concentration in the extract was higher by 67%.     

An efficient new method for extraction, separation and purification of psoralen and isopsoralen from Fructus Psoraleae by supercritical fluid extraction and high-speed counter-current chromatography

Psoralen and isopsoralen were extracted from Fructus Psoraleae (Psoralea corylitolia L.) by supercritical CO2. The effect of various parameters, i.e., pressure, temperature and sample particle size on yield was investigated with an analytical-scale supercritical fluid extraction (SFE) system to find the optimal conditions. The process was then scaled up by 50 times with a preparative SFE system under the optimized conditions of pressure (26 MPa), temperature (60 degrees C) and a sample particle size of 40-60 mesh. The yield of the preparative SFE was 9.1% and the combined yield of psoralen and isopsoralen was 2.5 mg/g of dry seeds. Psoralen and isopsoralen in the extract were separated and purified by high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.7:1:0.8, v/v), and the fractions were analyzed by HPLC, MS, 1HNMR and 13C NMR. The structures of the products were further confirmed by comparison with authentic samples (National Institute of the Control of Pharmaceutical and Biological Products, Beijing, China).     

Supercritical fluid extraction for liquid chromatographic determination of carotenoids in Spirulina Pacifica algae: a chemometric approach

An experimental design procedure was used to investigate the effects of some operating parameters on the supercritical fluid extraction of carotenoids beta-carotene, beta-cryptoxanthin and zeaxanthin from Spirulina Pacifica algae, a carotenoid-rich dietary product. Variables tested were temperature and pressure of the supercritical fluid, dynamic extraction time and percentage of ethanol added as the modifier. Each variable was tested at three levels; 31 experiments were performed in random order. Analyses of the extracts were performed by high-performance liquid chromatography with UV-Vis photodiode array detection. Analytical responses (chromatographic peak areas) were processed by using a stepwise multiple regression analysis, in order to find polynomial functions describing the relationships between variables and responses. For all the analytes the experimental conditions providing the highest extraction yield inside the experimental domain considered were found. Supercritical fluid extraction results obtained in these conditions were compared with those obtained by performing solvent extraction in order to evaluate the effectiveness of the supercritical fluid extraction procedure.     

Optimization of parameters for the supercritical fluid extraction in the determination of N-nitrosamines in rubbers

The study of the possibilities of supercritical fluid extraction (SFE) with N-nitrosamines in rubbers has been carried out. Home-made materials fortified with several N-nitrosamines were prepared in order to optimize the SFE parameters. A Plackett-Burman design was employed to evaluate the influence of those parameters to be controlled in SFE, such as pressure, temperature, static and dynamic time, restrictor temperature and volume of modifier while CO2 was used as the extraction fluid. An extra central composite design for the main factors (according to the previously obtained results) was also developed in order to refine the best supercritical conditions for the extraction of N-nitrosamines from rubbers. Gas chromatography with a nitrogen and phosphorus sensitive detector was used to achieve sensitivity and limits of detection for the concentrations expected in plastic materials. The proposed analytical method has shown to be useful in the determination of N-nitrosamines even for complex matrices.     

Extraction of uranium from simulated ore by the supercritical carbon dioxide fluid extraction method with nitric acid-TBP complex.

The supercritical fluid extraction (SFE) method using CO(2) as a medium with an extractant of HNO(3)-tri-n-butyl phosphate (TBP) complex was applied to extract uranium from several uranyl phosphate compounds and simulated uranium ores. An extraction method consisting of a static extraction process and a dynamic one was established, and the effects of the experimental conditions, such as pressure, temperature, and extraction time, on the extraction of uranium were ascertained. It was found that uranium could be efficiently extracted from both the uranyl phosphates and simulated ores by the SFE method using CO(2). It was thus demonstrated that the SFE method using CO(2) is useful as a pretreatment method for the analysis of uranium in ores.     

Optimization of supercritical fluid extraction by carbon dioxide with organic modifiers of polycyclic aromatic hydrocarbons from urban particulate matter

The main advantages of using supercritical fluids for the extractions of organic pollutants from environmental matrix is that they are inexpensive, contaminant free, and less costly to dispose safely than organic solvents. In this work, a series of extraction experiments were carried out using CO2 as supercritical fluid on a certified sample of "Urban dust" (NIST S.R.M. 1649a) to optimize the analytical parameters with the aim of investigating the extraction limit of organic pollutant by using an almost "organic solvent-free" technique. The certified sample contains small concentrations of several organic pollutants, as PAH and PCB. The initial tests of extraction were carried out with only CO2 in supercritical phase, by maintaining the temperature at 50 degrees C and 80 degrees C and by making the pressure vary between 230 bar and 600 bar. The effect of three organic modifiers (methanol, n-hexane and toluene), added at 5% in volume, has been considered. The yield of recovery has been estimated for anthracene, fluoranthene, chrysene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene by GC-MS according to the increasing molecular weight.     

超临界二氧化碳萃取秋水仙碱（英文）

 利用超临界二氧化碳对秋水仙块根（经粉碎）中的秋水仙碱进行了萃取,采用高效液相色谱法对萃取出的秋水仙碱的质量分数进行了测定。实验选择40℃20～40MPa作为超临界苹取的操作条件,采用体积分数为95％的乙醇在索氏提取器中对样品进行了对比苹取实验。结果表明:不加浸泡剂进行浸泡处理的样品中的秋水仙碱很难被超临界二氧化碳萃取,在40℃,35MPa条件下,消耗1．28mol的二氧化碳只得到3％的萃取率。加入极少量的有机溶剂浸泡处理样品15min后再进行超临界萃取,可以极大程度地提高秋水仙碱的萃取率。     

超临界流体萃取在天然药物分析中的应用

按物质的不同性质综述了１９９５年以来超临界流体萃取技术在天然药物分析中的一些进展情况,常见的分析主要包括萜类、生物碱、黄酮类、挥发油及苯丙素类。超临界流体萃取作为一门新型的样品前处理技术,在天然药物的分离分析中展示了其特有的优点。该技术操作温度低,不会引起热敏性的分解变质;使用的有毒溶剂少,从而减少化学药品对药物的污染。     

Effect of plant matrix and fluid ethanol concentration on supercritical fluid extraction efficiency of schisandrin derivatives

An investigation of the effect of plant matrix on the supercritical fluid extraction efficiency of five schisandrin derivatives is reported, exhibiting a great difference with respect to extraction efficiency depending on the matrix. Pure supercritical CO2 at 60 degrees C and 34.0 MPa cannot fully recover schisandrin derivatives from the leaves as much as from the other matrices. Only 36.9% of these compounds are extracted from leaves of Schisandra chinensis by supercritical CO2 in comparison with organic solvent extraction. However, more than 80% of schisandrin derivatives are obtained from both stem and fruit parts. Ethanol addition also shows a different effect depending on plant matrix; that is, CO2 modified with 10% ethanol could enhance the yield of schisandrin derivatives from leaves by four times when compared with that of pure CO2, but it has little effect on both stems and fruits.     

Supercritical CO2 extract from needles of Pinus nigra ssp. laricio: combined analysis by GC, GC-MS and 13C NMR

The chemical composition of the volatile concentrate prepared by supercritical CO(2) extraction of the needles of Pinus nigra Arnold ssp. laricio Poiret from Corsica was investigated using GC (RI), GC-MS and (13)C NMR spectroscopy. The major component was by far manoyl oxide (63%), a compound of potential interest for the perfumery and pharmaceutical industries. Consequently, the supercritical fluid extract of P. nigra ssp. laricio (yield 1.60%) could be considered as a source of this diterpene.     

Supercritical CO2 extraction of emodin and physcion from Polygonum cuspidatum and subsequent isolation by semipreparative chromatography

Emodin and physcion are abundant anthraquinone compounds found in the traditional Chinese medicinal herb Polygonum cuspidatum Sied. et Zucc. In this paper, emodin and physcion were successfully extracted with supercritical CO2 plus ethanol modifier after the extraction conditions were optimized with uniform design-sequential optimization. Results showed that the ethanol modifier concentration was the main factor for the effective extraction of the emodin. The optimal extraction condition was obtained: 20 MPa, 30 degrees C, and 95% ethanol, at which the yields of emodin and physcion were 0.616 and 0.178 g/100 g, respectively. The yield obtained by supercritical fluid extraction (SFE) was a little lower than that obtained by sonication extraction (SE). The crude extract obtained by SFE was further isolated and purified by semipreparative chromatography with the mobile phase composed of methanol-water (90:1, v/v). Emodin and physcion were obtained with purity 98.6 and 99.1%, respectively, when determined by HPLC, and identification was performed by retention time and UV spectra of the standards. The result suggested that SFE is an alternative and promising method for extraction of the two compounds from P. cuspidatum owing to its environment-friendly properties and fewer coextracts.     

Supercritical fluid extraction of grape seed oil and subsequent separation of free fatty acids by high-speed counter-current chromatography

Supercritical fluid extraction (SFE) of grape seed oil was performed to study the effect of various parameters such as pressure, temperature and the particle size of the sample on the yield and composition of oil using an analytical-scale SFE system. Then the extraction was scaled up by 125 times using a preparative SFE system under the optimized conditions of high pressure (30-40 MPa) and low temperature (35-40 degrees C) with medium particle size (20-40 mesh). The maximum yield of the oil can reach 6.2% with pure supercritical CO2 and 4.0% more oil can be obtained by adding 10% of ethanol as modifier. The unsaturated fatty acids (UFSs) make up about 70% in the oil on the basis of free fatty acids. The grape seed oil was then subjected to separation and purification for free fatty acids after saponification by high-speed counter-current chromatography coupled with evaporative light scattering detection (ELSD). The separation of 1.0 g of oil can yield about 430 mg pure linoleic acid at 99% purity. The fatty acids were analyzed by HPLC-ELSD.     

环境模拟样品中多环芳烃的超临界流体萃取I．利用正交设计选择最佳萃取条件

采用正交设计实验方法，研究了从环境模拟样品中超临界流体萃取（ＳＦＥ）多环芳烃（ＰＡＨ）的最佳萃取条件。着重考察了超临界流体的压力、温度和用量等对萃取效率的影响。结果表明，压力的影响居第一位，温度影响次之，超临界ＣＯ２的用量的影响居第三位。建立了选择超临界流体萃取条件的简单方法     

Simultaneous supercritical fluid derivatization and extraction of formaldehyde by the Hantzsch reaction

A study where the Hantzsch reaction is used to produce the chemical derivatization of formaldehyde in a supercritical medium is presented in this paper. Pressure, temperature and other parameters such as static and dynamic extraction time must be optimized to increase the yield of this kinetically controlled reaction. A 2(5-1) (resolution V) factorial design was used to study the significant parameters affecting the supercritical process in terms of resolution and sensitivity. A subsequent central composite design was employed to find the conditions of maximum response. Ultraviolet-visible spectrophotometry was used as the detection technique. The optimum conditions were used for the determination of formaldehyde in real finger-paints by means of the previous addition of known quantities of this analyte to the paint. Results were compared with those obtained with supercritical fluid extraction and subsequent chemical derivatization and an improvement of sensitivity as well as a reduction of time of analysis, solvent waste and reagents consumption were observed.     

Effect of sample handling on alkaloid and mineral content of aqueous extracts of greater celandine (Chelidonium majus L.)

The authors examined the extraction of alkaloids from the greater celandine (Chelidonium majus L.) by different methods (traditional pressing and tea making, microwave and supercritical fluid extraction). The extractants were water and propylene glycol. For comparison of the extraction methods, the yield was evaluated according to total alkaloid content measured by spectroscopy. The highest alkaloid yield was obtained by microwave extraction and by making tea. Distribution of the components was studied by thin-layer chromatography and densitometry. The concentration and the ratio of alkaloid components in extracts are significantly different depending on the extraction method. The solution obtained by supercritical fluid extraction contains coptisine and chelidonine, while berberine could be obtained by microwave extraction only. Extracts with high coptisine content were obtained by supercritical fluid extraction, followed by pressing and microwave extraction. Mineral element content of the drug and extracts was also determined by inductively coupled plasma atomic emission spectrometry. Element content (Na, Ca, Fe) was found to be highest in microwave extracts.     

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.     

Monitoring supercritical fluid extraction by thermal lens spectrometry with pulsed laser excitation

A dual-beam thermal lens spectrometer (TLS) with a pulse pump–probe coaxial configuration was coupled to commercially available supercritical fluid extraction equipment using a high-pressure flow cell interface. Because of its feasible critical parameters, moderate cost and good thermooptical properties, carbon dioxide was used as supercritical solvent. Using trans-β-carotene as analyte, several factors related with the extraction process under continuos flow conditions were studied in order to establish their influence in the thermal lens signal magnitude. Under the optimum experimental conditions, the relative TLS signal area showed a linear relationship with the concentration of trans-β-carotene from 1.5×10⁻⁶ to 8×10⁻⁸ M (n=5, r=0.998) in the supercritical phase. Thus, the viability of on-line detection for supercritical fluid extraction with a pulse thermal lens spectrometer was demonstrated.