In recent times, the overall interest over Supercritical Fluid Chromatography (SFC) is truly growing within various domains but especially for pharmaceutical analysis. However, in the best of our knowledge modern SFC ...In recent times, the overall interest over Supercritical Fluid Chromatography (SFC) is truly growing within various domains but especially for pharmaceutical analysis. However, in the best of our knowledge modern SFC is not yet applied for drug quality control in the daily routine framework. Among the numerous reported SFC methods, none of them could be found to fully satisfy to all steps of the analytical method lifecycle. Thereby, the present contribution aims to provide an overview of the current and past achievements related to SFC techniques, with a targeted attention to this lifecycle and its successive steps. The included discussions were therefore structured accordingly and emphasizing the analytical method lifecycle in accord with the International Conference on Harmonisation (ICH). Recent and important scientific outputs in the field of analytical SFC, as well as instrumental evolution, qualification strategies, method development methodologies and discussions on the topic of method validation are reviewed.展开更多
An efficient and environment-friendly method for simultaneous determination of 13 typical derivatives of polycyclic aromatic hydrocarbon(PAH)in petroleum-polluted soil with nitro-,oxy-and alkylfunctional group was dev...An efficient and environment-friendly method for simultaneous determination of 13 typical derivatives of polycyclic aromatic hydrocarbon(PAH)in petroleum-polluted soil with nitro-,oxy-and alkylfunctional group was developed using supercritical fluid extraction(SFE)followed by ultra-high performance supercritical fluid chromatography(UHPSFC).Parameters of UHPSFC,including type of stationary phase and mobile phase modifiers,gradient elution process,backpressure,column temperature,and the flow rate of mobile phase,were systematically optimized,achieving a fast separation within4.2 min.Limits of detection(LOD)were 0.005-0.1μg mL^(-1)or 0.1-2.0 ng g^(-1),respectively,with a good repeatability(RSD<5.0%).Before UHPSFC-PDA analysis,the PAH-derivatives in soil samples were effectively enriched in 15.0 min using SFE with an online carbon nanotubes(CNTs)collection trap.The soil samples were analyzed by the proposed method and the results were verified by GC-MS.Thus,SFE equipped with an online CNTs trap followed by UHPSFC-PDA analysis,which only consumed about2.0 mL organic solvent for a whole run,has been demonstrated to be an efficient way for screening and quantitative analysis of trace-level PAH-derivatives in soil samples.展开更多
Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry...Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) was developed to simultaneously determine 11 amino acids in different types of tea (green teas, Oolong tea, black tea and Pu-erh tea). The separation conditions for the analysis of the selected amino acids including the column type, temperature and backpressure as well as the type of additive, were carefully optimized. The best separation of the 11 amino acids was obtained by adding water (5%, v/v) and trifluoroacetic acid (0.4%, v/v) to the organic modifier (methanol). Finally, the developed SFC-MS method was fully validated and successfully applied to the determination of these amino acids in six different tea samples. Good linearity (r ≥ 0.993), precision (RSDs≤ 2.99%), accuracy (91.95%-107.09%) as well as good sample stability were observed. The limits of detection ranged from 1.42 to 14.69 ng/mL, while the limits of quantification were between 4.53 and 47.0 ng/mL. The results indicate that the contents of the 11 amino acids in the six different tea samples are greatly influenced by the degree of fermentation. The proposed SFC-MS method shows a great potential for further investigation of tea varieties.展开更多
Supercritical fluid chromatography(SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the a...Supercritical fluid chromatography(SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the advances of SFC in targeted and untargeted lipid profiling. The advancement of the SFC instruments and the stationary phases are summarized. Typical applications of SFC to the targeted and untargeted lipid profiling are discussed in detail. Moreover, the perspectives of SFC in the lipid profiling are also proposed. As a useful and promising tool for investigating lipids in vitro and in vivo, SFC will predictably obtain further development.展开更多
In 1822, almost 200 years ago, Baron Charles Cagniard de Latour (1777-1859) discovered the critical phenomena or critical state [1] [2]. At that time, it was described as a curiosity. However, it is now used as an adv...In 1822, almost 200 years ago, Baron Charles Cagniard de Latour (1777-1859) discovered the critical phenomena or critical state [1] [2]. At that time, it was described as a curiosity. However, it is now used as an advanced extraction and analytical technology in industry and research. Extraction with supercritical fluids (SFs) was welcome from the very beginning. In the present paper, the application to chromatography of the critical phenomena of compressed gases or overheated liquids as supercritical fluids will be discussed. Supercritical Fluid Chromatography (SFC) received an uneasy welcome, mainly because of the lack of commercially available analytical instruments. Even today, only a small number of industrial companies are manufacturing SFC instrumentation. A very small spectrum of columns is manufactured specially for SFC. SFC is not accepted by Pharmacopeia committees for the analysis of drugs and medical forms to the same extent as Gas Chromatography, High-Performance Liquid Chromatography or even Thin Layer Chromatography. The present status and future perspectives for SFC will be discussed.展开更多
A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scal...A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scale. Among 11 different 2 stationary phases the Chiral cel OD-H column showed by far the best separation properties. The influence of different modifiers, injection solvents, temperature, and pressure, and density of the fluid, respectively, on the separation behaviour has been studied. It was found that the separation behaviour strongly depends on the type of modifier and the modifier content. Temperature and pressure are of less influence.展开更多
This paper depicts a brief review on the applications of packed supercritical fluid chromatography (SFC) in palm oil analyses and purifications from early 1990s to date. Packed SFC has been used for the analyses of va...This paper depicts a brief review on the applications of packed supercritical fluid chromatography (SFC) in palm oil analyses and purifications from early 1990s to date. Packed SFC has been used for the analyses of various palm oil components. The analytical separations have also been scaled up to preparative scale that leads to the recovery of high value components from palm oil. This review encompasses both analytical and preparative SFC in the oil palm processing.展开更多
1 INTRODUCTIONSupercritical fluid chromatography(SFC),employing supercritical fluid as mobilephase,originated in the 1960’s [1-4].Since 1980’s extensive research work has beenperformed on SFC,chiefly for analytical ...1 INTRODUCTIONSupercritical fluid chromatography(SFC),employing supercritical fluid as mobilephase,originated in the 1960’s [1-4].Since 1980’s extensive research work has beenperformed on SFC,chiefly for analytical purposes [5,6].SFC was then adopted for thedetermination of thermodynamic properties such as partial molar volume,and partialmolar enthalpy of solutes in both mobile phase and stationary phase and the solutedistribution coefficient between two phases [7- 11].Partial molar properties can be de-展开更多
It is important to understand the mechanism and implications of different modifiers on analytical and preparative processes under chromatography with supercritical fluids (SFs) and under extraction with SFs. Supercrit...It is important to understand the mechanism and implications of different modifiers on analytical and preparative processes under chromatography with supercritical fluids (SFs) and under extraction with SFs. Supercritical fluid chromatography (SFC) and supercritical fluid extraction are generally carried out with neat supercritical carbon dioxide (SCCO2) or with SCCO2 containing modifiers (or cosolvents), especially for strongly polar compounds. For example, methanol is added as a cosolvent/modifier to SCCO2 for the extraction/separation of polar compounds. This paper discusses the influence of the modifier on the colligative properties of the principal mobile phase, which may define the situation in the total mobile phase in a chromatography column or in parts of a column under SFC. No colligative behavior of solutions reflects individual properties of the solutes. Their cross-interactions with solvents are discussed.展开更多
Enantioseparation of threeβ-blockers,i.e.,atenolol,metoprolol and propranolol,was studied on amylose tris(3-chloro-5-methylphenylcarbamate)immobilized chiral stationary phase using supercritical fluid chromatography(...Enantioseparation of threeβ-blockers,i.e.,atenolol,metoprolol and propranolol,was studied on amylose tris(3-chloro-5-methylphenylcarbamate)immobilized chiral stationary phase using supercritical fluid chromatography(SFC).The effect of organic modifiers(methanol,isopropanol and their mixture),column temperature and back pressure on chiral separation ofβ-blockers was evaluated.Optimum chromatographic separation with respect to resolution,retention,and analysis time was achieved using a mixture of CO_(2) and 0.1%isopropyl amine in isopropanol:methanol(50:50,V/V),in 75:25(V/V)ratio.Under the optimized conditions,the resolution factors(Rs)and separation factors(a)were greater than3.0 and 1.5,respectively.Further,with increase in temperature(25-45℃)and pressure(100-150 bars)there was corresponding decrease in retention factors(k),a and Rs.However,a reverse trend(a and Rs)was observed for atenolol with increase in temperature.The thermodynamic data from van’t Hoff plots revealed that the enantioseparation was enthalpy driven for metoprolol and propranolol while entropy driven for atenolol.To understand the mechanism of chiral recognition and the elution behavior of the enantiomers,molecular docking studies were performed.The binding energies obtained from simulation studies were in good agreement with the elution order found experimentally and also with the free energy values.The method was validated in the concentration range of 0.5-10μg/m L for all the enantiomers.The limit of detection and limit of quantitation ranged from 0.126 to 0.137μg/m L and 0.376-0.414μg/m L,respectively.The method was used successfully to analyze these drugs in pharmaceutical preparations.展开更多
Recently there has been a resurgence of interest in cyclic peptides due to their therapeutic advantages in terms of potency, permeability, proteolytic stability, and unique selectivity relative to traditional smaller ...Recently there has been a resurgence of interest in cyclic peptides due to their therapeutic advantages in terms of potency, permeability, proteolytic stability, and unique selectivity relative to traditional smaller drug molecules. Cyclosporin is a family of cyclic peptides widely used as autoimmune suppression agents. Cyclosporin analogs consist of eleven amino acids with the main difference lying at the side chain of its amino acid residues. In this study, a single step separation method was developed utilizing Supercritical Fluid Chromatography (SFC) to resolve five naturally occurring cyclosporin analogs (Cyclosporin A, B, C, D, and H) on a bare silica-packed column. The optimized method involved use of ethanol-modified carbon dioxide as mobile phase on a bare silica column at 80 °C and UV detection at 220 nm. Although column temperature and back pressure generally had insignificant effect on SFC separation, it was found in our study that increasing temperature and pressure greatly improved peak shape and resolution.展开更多
Modifiers have a broad array of influences on extraction with liquids in standard state, supercritical fluid extraction (SFE), trapping by SFE and supercritical fluid chromatography (SFC). They can significantly chang...Modifiers have a broad array of influences on extraction with liquids in standard state, supercritical fluid extraction (SFE), trapping by SFE and supercritical fluid chromatography (SFC). They can significantly change the qualitative and quantitative results. Quantitative and qualitative results can be influenced by different extractants and modifiers in different ways as it was shown by Brondz et al. at 2007 in “The real nature of the indole alkaloids in Cortinarius infractus: Evaluation of artifact formation through solvent extraction method development”, J. Chromatography A, 1148, 1-7. The choice of correct extractant, modifier, and trapper to the bulk mobile phase for supercritical fluids (SFs) or for liquids in subcritical or in the liquids in standard state is a challenge in any extraction procedure. This is the second paper in a sequence that describes the influence of extractants and modifiers on the performance of SFs and results of extraction with liquids in standard state and SFE. Here, attention is given to possible mistakes in qualitative and quantitative results by poor understanding of the influence of extractants, modifiers, and trappers on extraction and trapping process by a careless choice of extractant, modifier, and trapper for extraction with liquids in standard state and SFE. The SF chosen for discussion in the paper is CO2. However, similar effects can be observed with use of other SFs and fluids in subcritical and standard states. In this paper, the discussion of lipids, fatty and carboxylic acids have been chosen as target analytes for extraction, trapping and analysis. Some examples from extraction with liquids in the standard state and trapping in the supercritical state (collection) have been furnished with the wrong extractant, modifier, or trapper which is presented for illustration of inappropriate choice of extractants, modifiers, and trappers.展开更多
Constant-volume heat capacities of supercritical (SC) CO2, SC CO2-n-pentane, and SC CO2-n-heptane mixtures were determined at 308.15 K in the pressure range from 6 to 12 MPa. It was found that there is a maximum in ea...Constant-volume heat capacities of supercritical (SC) CO2, SC CO2-n-pentane, and SC CO2-n-heptane mixtures were determined at 308.15 K in the pressure range from 6 to 12 MPa. It was found that there is a maximum in each heat capacity vs pressure curve. Intermolecular interaction in the fluids was studied.展开更多
A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separat...A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separation of some fat-soluble components in foods. Three columns including a trap column,concentration column and analytical column were used for trapping the fat-soluble components, on-line enrichment and reverse phase separation, respectively. Capsaicinoids were on-line extracted by a CO_2 supercritical fluid, then concentrated and separated by using the C_(18) columns, finally detected by mass spectrometry(MS). Capsaicin eluted at 10.1 min and limit of detection(LOD, S/N=3) for the standard solution is 0.55pg. The linearity was calculated with a value of coefficient of determination(R^2)≥0.998 in the range of 1.1–8.5 ng. Concentrations of capsaicin in the green, yellow, and red bell peppers were determined to be 60.33 ng/g, 31.79 ng/g, 35.38ng/g, respectively.展开更多
In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts...In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60 ℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed by dynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.展开更多
A series of TiO 2-MoO 3 nano-composite photocatalysts were prepared by supercritical fluid dry method(SCFD) and an impregnation technique with TiCl 4 and (NH 4) 6Mo 7O 24 ·4H 2O as the starting materia...A series of TiO 2-MoO 3 nano-composite photocatalysts were prepared by supercritical fluid dry method(SCFD) and an impregnation technique with TiCl 4 and (NH 4) 6Mo 7O 24 ·4H 2O as the starting materials. The catalysts were characterized by the means of XRD, TEM and UV-Vis. Methyl orange was used as model compound for the evaluation of their catalytic activities. The results indicated that the photo-catalyst prepared by SCFD had the advantages of small size(12.84 nm), narrow distribution and good dispersivity. The presence of small amount of Mo in composite catalyst gives rise to the red shift of its absorbance wavelength, decrease of its energy gap and increase of the utility of visible light. Furthermore, higher surface acidity of the photo-catalyst was obtained as the result of the addition of MoO 3. Compared with pure TiO 2, the catalytic activity of the TiO 2-MoO 3 nano-composite photo-catalyst was improved significantly. As the doping concentration of the composite catalysts was controlled at 0.6%(molar percentage), 100% degradation of methyl orange was achieved with in 1.2 h irradiation time.展开更多
Crosslinking experin(?)tnts for the chiral stationary phase OV-225-L-Val-t-butylamide within both fused silica and glass capillary columns have been carried out.Amino acid enantiomers were separated on crosslinked col...Crosslinking experin(?)tnts for the chiral stationary phase OV-225-L-Val-t-butylamide within both fused silica and glass capillary columns have been carried out.Amino acid enantiomers were separated on crosslinked columns by、both GC and SFC methods.In SFC,the α values of amino acid enantiomers are independent of the density of the mobile phase,and they are hig her than those obtained by GC for the tested enantiomers with the same column due to the lower column tempera- ture used in SFC.展开更多
Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology ha...Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology has been considered to be an environmentally-benign treatment. Therefore, its technology was applied for a conversion of biomass to useful fuels and chemicals in order to mitigate environmental loading. For example, supercritical water treatment has demonstrated that lignocellulosics can be hydrolyzed to become lignin-derived products for useful aromatic chemicals and carbohydrate-derived products, such as polysaccharides, oligosaccharides and monosaccharides of glucose, mannose and xylose used for subsequent ethanol fermentation. If this treatment is prolonged, lignocellulosics were found to be converted to organic acids such as formic, acetic, glycolic and lactic acids which can be converted to methane for biofuel. When alcohols, such as methanol and ethanol, were used instead of water, some other useful products were achieved, and its liquefied products were found to have a potential for liquid biofuel. In this study, therefore, our research achievements in supercritical fluid science of woody biomass will be introduced for clean and green chemistry for a sustainable environment.展开更多
文摘In recent times, the overall interest over Supercritical Fluid Chromatography (SFC) is truly growing within various domains but especially for pharmaceutical analysis. However, in the best of our knowledge modern SFC is not yet applied for drug quality control in the daily routine framework. Among the numerous reported SFC methods, none of them could be found to fully satisfy to all steps of the analytical method lifecycle. Thereby, the present contribution aims to provide an overview of the current and past achievements related to SFC techniques, with a targeted attention to this lifecycle and its successive steps. The included discussions were therefore structured accordingly and emphasizing the analytical method lifecycle in accord with the International Conference on Harmonisation (ICH). Recent and important scientific outputs in the field of analytical SFC, as well as instrumental evolution, qualification strategies, method development methodologies and discussions on the topic of method validation are reviewed.
基金financially supported by the National Natural Science Foundation of China(No.21874153)Science Foundation of China University of Petroleum,Beijing(No.2462017BJB09)PetroChina Innovation Foundation(No.2016D-5007-0402)。
文摘An efficient and environment-friendly method for simultaneous determination of 13 typical derivatives of polycyclic aromatic hydrocarbon(PAH)in petroleum-polluted soil with nitro-,oxy-and alkylfunctional group was developed using supercritical fluid extraction(SFE)followed by ultra-high performance supercritical fluid chromatography(UHPSFC).Parameters of UHPSFC,including type of stationary phase and mobile phase modifiers,gradient elution process,backpressure,column temperature,and the flow rate of mobile phase,were systematically optimized,achieving a fast separation within4.2 min.Limits of detection(LOD)were 0.005-0.1μg mL^(-1)or 0.1-2.0 ng g^(-1),respectively,with a good repeatability(RSD<5.0%).Before UHPSFC-PDA analysis,the PAH-derivatives in soil samples were effectively enriched in 15.0 min using SFE with an online carbon nanotubes(CNTs)collection trap.The soil samples were analyzed by the proposed method and the results were verified by GC-MS.Thus,SFE equipped with an online CNTs trap followed by UHPSFC-PDA analysis,which only consumed about2.0 mL organic solvent for a whole run,has been demonstrated to be an efficient way for screening and quantitative analysis of trace-level PAH-derivatives in soil samples.
基金the financial support from China Postdoctoral Science Foundation(2018M643205)
文摘Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) was developed to simultaneously determine 11 amino acids in different types of tea (green teas, Oolong tea, black tea and Pu-erh tea). The separation conditions for the analysis of the selected amino acids including the column type, temperature and backpressure as well as the type of additive, were carefully optimized. The best separation of the 11 amino acids was obtained by adding water (5%, v/v) and trifluoroacetic acid (0.4%, v/v) to the organic modifier (methanol). Finally, the developed SFC-MS method was fully validated and successfully applied to the determination of these amino acids in six different tea samples. Good linearity (r ≥ 0.993), precision (RSDs≤ 2.99%), accuracy (91.95%-107.09%) as well as good sample stability were observed. The limits of detection ranged from 1.42 to 14.69 ng/mL, while the limits of quantification were between 4.53 and 47.0 ng/mL. The results indicate that the contents of the 11 amino acids in the six different tea samples are greatly influenced by the degree of fermentation. The proposed SFC-MS method shows a great potential for further investigation of tea varieties.
基金supported by the National Natural Science Foundation of China (Grant No. 21775047)Pearl River S and T Nova Program of Guangzhou, China (Grant No. 201806010055)the Fundamental Research Funds for the Central Universities (Grant No. 2018MS55)
文摘Supercritical fluid chromatography(SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the advances of SFC in targeted and untargeted lipid profiling. The advancement of the SFC instruments and the stationary phases are summarized. Typical applications of SFC to the targeted and untargeted lipid profiling are discussed in detail. Moreover, the perspectives of SFC in the lipid profiling are also proposed. As a useful and promising tool for investigating lipids in vitro and in vivo, SFC will predictably obtain further development.
文摘In 1822, almost 200 years ago, Baron Charles Cagniard de Latour (1777-1859) discovered the critical phenomena or critical state [1] [2]. At that time, it was described as a curiosity. However, it is now used as an advanced extraction and analytical technology in industry and research. Extraction with supercritical fluids (SFs) was welcome from the very beginning. In the present paper, the application to chromatography of the critical phenomena of compressed gases or overheated liquids as supercritical fluids will be discussed. Supercritical Fluid Chromatography (SFC) received an uneasy welcome, mainly because of the lack of commercially available analytical instruments. Even today, only a small number of industrial companies are manufacturing SFC instrumentation. A very small spectrum of columns is manufactured specially for SFC. SFC is not accepted by Pharmacopeia committees for the analysis of drugs and medical forms to the same extent as Gas Chromatography, High-Performance Liquid Chromatography or even Thin Layer Chromatography. The present status and future perspectives for SFC will be discussed.
文摘A packed column supercritical fluid chromatography (SFC) method for the separation of clopidogrel enantiomers on a chiral stationary phase and CO2 with modifier as mobile phase has been developed at an analytical scale. Among 11 different 2 stationary phases the Chiral cel OD-H column showed by far the best separation properties. The influence of different modifiers, injection solvents, temperature, and pressure, and density of the fluid, respectively, on the separation behaviour has been studied. It was found that the separation behaviour strongly depends on the type of modifier and the modifier content. Temperature and pressure are of less influence.
文摘This paper depicts a brief review on the applications of packed supercritical fluid chromatography (SFC) in palm oil analyses and purifications from early 1990s to date. Packed SFC has been used for the analyses of various palm oil components. The analytical separations have also been scaled up to preparative scale that leads to the recovery of high value components from palm oil. This review encompasses both analytical and preparative SFC in the oil palm processing.
文摘1 INTRODUCTIONSupercritical fluid chromatography(SFC),employing supercritical fluid as mobilephase,originated in the 1960’s [1-4].Since 1980’s extensive research work has beenperformed on SFC,chiefly for analytical purposes [5,6].SFC was then adopted for thedetermination of thermodynamic properties such as partial molar volume,and partialmolar enthalpy of solutes in both mobile phase and stationary phase and the solutedistribution coefficient between two phases [7- 11].Partial molar properties can be de-
文摘It is important to understand the mechanism and implications of different modifiers on analytical and preparative processes under chromatography with supercritical fluids (SFs) and under extraction with SFs. Supercritical fluid chromatography (SFC) and supercritical fluid extraction are generally carried out with neat supercritical carbon dioxide (SCCO2) or with SCCO2 containing modifiers (or cosolvents), especially for strongly polar compounds. For example, methanol is added as a cosolvent/modifier to SCCO2 for the extraction/separation of polar compounds. This paper discusses the influence of the modifier on the colligative properties of the principal mobile phase, which may define the situation in the total mobile phase in a chromatography column or in parts of a column under SFC. No colligative behavior of solutions reflects individual properties of the solutes. Their cross-interactions with solvents are discussed.
基金Department of Chemistry,Gujarat University,for supporting this workHuman Resource Development GroupCouncil of Scientific&Industrial Research(CSIR),New Delhi,for Research Associate Fellowship(File No.:09/070(0058)2K18 EMR-I)。
文摘Enantioseparation of threeβ-blockers,i.e.,atenolol,metoprolol and propranolol,was studied on amylose tris(3-chloro-5-methylphenylcarbamate)immobilized chiral stationary phase using supercritical fluid chromatography(SFC).The effect of organic modifiers(methanol,isopropanol and their mixture),column temperature and back pressure on chiral separation ofβ-blockers was evaluated.Optimum chromatographic separation with respect to resolution,retention,and analysis time was achieved using a mixture of CO_(2) and 0.1%isopropyl amine in isopropanol:methanol(50:50,V/V),in 75:25(V/V)ratio.Under the optimized conditions,the resolution factors(Rs)and separation factors(a)were greater than3.0 and 1.5,respectively.Further,with increase in temperature(25-45℃)and pressure(100-150 bars)there was corresponding decrease in retention factors(k),a and Rs.However,a reverse trend(a and Rs)was observed for atenolol with increase in temperature.The thermodynamic data from van’t Hoff plots revealed that the enantioseparation was enthalpy driven for metoprolol and propranolol while entropy driven for atenolol.To understand the mechanism of chiral recognition and the elution behavior of the enantiomers,molecular docking studies were performed.The binding energies obtained from simulation studies were in good agreement with the elution order found experimentally and also with the free energy values.The method was validated in the concentration range of 0.5-10μg/m L for all the enantiomers.The limit of detection and limit of quantitation ranged from 0.126 to 0.137μg/m L and 0.376-0.414μg/m L,respectively.The method was used successfully to analyze these drugs in pharmaceutical preparations.
文摘Recently there has been a resurgence of interest in cyclic peptides due to their therapeutic advantages in terms of potency, permeability, proteolytic stability, and unique selectivity relative to traditional smaller drug molecules. Cyclosporin is a family of cyclic peptides widely used as autoimmune suppression agents. Cyclosporin analogs consist of eleven amino acids with the main difference lying at the side chain of its amino acid residues. In this study, a single step separation method was developed utilizing Supercritical Fluid Chromatography (SFC) to resolve five naturally occurring cyclosporin analogs (Cyclosporin A, B, C, D, and H) on a bare silica-packed column. The optimized method involved use of ethanol-modified carbon dioxide as mobile phase on a bare silica column at 80 °C and UV detection at 220 nm. Although column temperature and back pressure generally had insignificant effect on SFC separation, it was found in our study that increasing temperature and pressure greatly improved peak shape and resolution.
文摘Modifiers have a broad array of influences on extraction with liquids in standard state, supercritical fluid extraction (SFE), trapping by SFE and supercritical fluid chromatography (SFC). They can significantly change the qualitative and quantitative results. Quantitative and qualitative results can be influenced by different extractants and modifiers in different ways as it was shown by Brondz et al. at 2007 in “The real nature of the indole alkaloids in Cortinarius infractus: Evaluation of artifact formation through solvent extraction method development”, J. Chromatography A, 1148, 1-7. The choice of correct extractant, modifier, and trapper to the bulk mobile phase for supercritical fluids (SFs) or for liquids in subcritical or in the liquids in standard state is a challenge in any extraction procedure. This is the second paper in a sequence that describes the influence of extractants and modifiers on the performance of SFs and results of extraction with liquids in standard state and SFE. Here, attention is given to possible mistakes in qualitative and quantitative results by poor understanding of the influence of extractants, modifiers, and trappers on extraction and trapping process by a careless choice of extractant, modifier, and trapper for extraction with liquids in standard state and SFE. The SF chosen for discussion in the paper is CO2. However, similar effects can be observed with use of other SFs and fluids in subcritical and standard states. In this paper, the discussion of lipids, fatty and carboxylic acids have been chosen as target analytes for extraction, trapping and analysis. Some examples from extraction with liquids in the standard state and trapping in the supercritical state (collection) have been furnished with the wrong extractant, modifier, or trapper which is presented for illustration of inappropriate choice of extractants, modifiers, and trappers.
文摘Constant-volume heat capacities of supercritical (SC) CO2, SC CO2-n-pentane, and SC CO2-n-heptane mixtures were determined at 308.15 K in the pressure range from 6 to 12 MPa. It was found that there is a maximum in each heat capacity vs pressure curve. Intermolecular interaction in the fluids was studied.
基金supported by the National Natural Science Foundation of China (No. 21621003)
文摘A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separation of some fat-soluble components in foods. Three columns including a trap column,concentration column and analytical column were used for trapping the fat-soluble components, on-line enrichment and reverse phase separation, respectively. Capsaicinoids were on-line extracted by a CO_2 supercritical fluid, then concentrated and separated by using the C_(18) columns, finally detected by mass spectrometry(MS). Capsaicin eluted at 10.1 min and limit of detection(LOD, S/N=3) for the standard solution is 0.55pg. The linearity was calculated with a value of coefficient of determination(R^2)≥0.998 in the range of 1.1–8.5 ng. Concentrations of capsaicin in the green, yellow, and red bell peppers were determined to be 60.33 ng/g, 31.79 ng/g, 35.38ng/g, respectively.
基金the Natural Science and Technology Foundation of Jilin Province(No.2 0 0 2 0 6 37- 1)
文摘In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60 ℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed by dynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.
文摘A series of TiO 2-MoO 3 nano-composite photocatalysts were prepared by supercritical fluid dry method(SCFD) and an impregnation technique with TiCl 4 and (NH 4) 6Mo 7O 24 ·4H 2O as the starting materials. The catalysts were characterized by the means of XRD, TEM and UV-Vis. Methyl orange was used as model compound for the evaluation of their catalytic activities. The results indicated that the photo-catalyst prepared by SCFD had the advantages of small size(12.84 nm), narrow distribution and good dispersivity. The presence of small amount of Mo in composite catalyst gives rise to the red shift of its absorbance wavelength, decrease of its energy gap and increase of the utility of visible light. Furthermore, higher surface acidity of the photo-catalyst was obtained as the result of the addition of MoO 3. Compared with pure TiO 2, the catalytic activity of the TiO 2-MoO 3 nano-composite photo-catalyst was improved significantly. As the doping concentration of the composite catalysts was controlled at 0.6%(molar percentage), 100% degradation of methyl orange was achieved with in 1.2 h irradiation time.
基金This work was supported by the National Natural Science Fundation of China.
文摘Crosslinking experin(?)tnts for the chiral stationary phase OV-225-L-Val-t-butylamide within both fused silica and glass capillary columns have been carried out.Amino acid enantiomers were separated on crosslinked columns by、both GC and SFC methods.In SFC,the α values of amino acid enantiomers are independent of the density of the mobile phase,and they are hig her than those obtained by GC for the tested enantiomers with the same column due to the lower column tempera- ture used in SFC.
文摘Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology has been considered to be an environmentally-benign treatment. Therefore, its technology was applied for a conversion of biomass to useful fuels and chemicals in order to mitigate environmental loading. For example, supercritical water treatment has demonstrated that lignocellulosics can be hydrolyzed to become lignin-derived products for useful aromatic chemicals and carbohydrate-derived products, such as polysaccharides, oligosaccharides and monosaccharides of glucose, mannose and xylose used for subsequent ethanol fermentation. If this treatment is prolonged, lignocellulosics were found to be converted to organic acids such as formic, acetic, glycolic and lactic acids which can be converted to methane for biofuel. When alcohols, such as methanol and ethanol, were used instead of water, some other useful products were achieved, and its liquefied products were found to have a potential for liquid biofuel. In this study, therefore, our research achievements in supercritical fluid science of woody biomass will be introduced for clean and green chemistry for a sustainable environment.