Determination of polycyclic aromatic hydrocarbons with supercritical fluid extraction and chromatography（SFE／SFC）

Ｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｐｏｌｙｃｙｃｌｉｃａｒｏｍａｔｉｃｈｙｄｒｏｃａｒｂｏｎｓｗｉｔｈｓｕｐｅｒｃｒｉｔｉｃａｌｆｌｕｉｄｅｘｔｒａｃｔｉｏｎａｎｄｃｈｒｏｍａｔｏｇｒａｐｈｙ（ＳＦＥ／ＳＦＣ）ＹａｏＷｅｉｘｉ（ＲｅｓｅａｒｃｈＣｅｎｔｅ...

Influence of Modifiers on Supercritical Fluid Chromatography (SFC) and Supercritical Fluid Extraction (SFE), Part I

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.

Simultaneous determination of amino acids in different teas using supercritical fluid chromatography coupled with single quadrupole 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.

Advances of supercritical fluid chromatography in lipid profiling

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.

Separation of Enantiomers of Clopidogrel on Chiral Stationary Phases by Packed Column Supercritical Fluid Chromatography

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.

Fast analysis of derivatives of polycyclic aromatic hydrocarbons in soil by ultra-high performance supercritical fluid chromatography after supercritical fluid extraction enrichment

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.

Chiral Separation of Ibuprofen by Supercritical Fluid Chromatography

The separation method using chiral stationary phase （CSP） for the preparation of enantioselective compound was widely used. In this work, supercritical fluid chromatography（SFC） was proposed to resolve the chiral mixtures. To determine the optimum operating conditions for the chiral separation of the racemic ibuprofen, the retention factors and resolutions with the change in pressure, temperature and the content of IPA （%, by volume） in supercritical CO2 were investigated. Experiments showed that the retention factor decreased with the increase of pressure and decrease in temperature. The retention factor was also influenced by the content of IPA in mobile phase, as the content of IPA in the supercritical fluid increased, the retention factor decreased. The resolution of the enantiomers became worse with the increase of IPA in the supercritical fluid. Through optimizing the experimental conditions, a SFC procedure with 13MPa, 311.15K and 4% IPA in CO2 was obtained. The peak shape of the enantiomers was symmetric with supercritical fluid chromatography when compared to the asymmetric peak shape obtained by the conventional liquid chromatography. This work demonstrated that the developed supercritical fluid chromatography procedure was suitable for the chiral separation of ibuprofen enantiomers.

Review: Isomer Separation, Chiral Resolution, and Structure Elucidation Analyses Are the Future of Analytical Supercritical Fluid Chromatography—Mass Spectrometry

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.

Packed Supercritical Fluid Chromatography for the Analyses and Preparative Separations of Palm Oil Minor Components

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.

THEORY FOR STEP AND PULSE METHOD OF SUPERCRITICAL FLUID CHROMATOGRAPHY

The paper presents a general retention formula for supercritical fluid chromatography at finite concentration. A new chromatographic rate theory based on the fugacities of solutes instead of concentrations is developed, thus relieving the restrictions of linear isothermal distribution and infinite dilution. An expression for retention values of a N component system including solvent is obtained by combining the rate theory with the mass balance equation of solutes in chromatography. It is shown that there are N-1 characteristic retention peaks for N components and the retention time can be calculated directly from the equilibrium properties of the components in both mobile phase and stationary phase at the given conditions. The theory can be reduced to the well known formula for infinite dilution and to the result of step-pulse theory in gas chromatography under low pressure at finite concentration. Supercritical fluid chromatography may eventually prove itself to be a useful reseach tool in the field of phase equilibrium and thermodynamic properties of supercritical fluid system.

Simultaneous enantioseparation and simulation studies of atenolol,metoprolol and propranolol on Chiralpak^■IG column 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.

Overview of the Analytical Lifecycle of Supercritical Fluid Chromatography Methods

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.

Rapid Separation of Five Cyclosporin Analogs by Supercritical Fluid Chromatography

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.

Influence of Modifiers, Extractants, and Trappers on Lipid Composition with Liquids in Standard State Extraction, Supercritical Fluid Extraction and Trapping by Supercritical Fluid Extraction, Part II

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.

Determination of Partial Molar Volumes of EPA and DHA Ethyl Esters in Supercritical Carbon Dioxide

The use of supercritical-fluid chromatography for determining partial molar volumes of ethyl esters of cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and cis -4,7,10,13,16,19- docosa-hexaenoic acid (DHA) in supercritical carbon dioxide is presented and discussed. Partial molar volumes of EPA and DHA esters are obtained from the variation of the retention properties with the density of mobile phase at 313.15 K, 323.15 K, 333.15 K and in the pressure range from 9 MPa to 21 MPa.

Product Analysis of Supercritical Fischer-Tropsch Synthesis: Utilizing a Unique On-Line and Off-Line Gas Chromatographs Setup in a Bench-Scale Reactor Unit

The utilization of supercritical fluids (SCF) in the Fischer-Tropsch Synthesis (FTS) further complicates the hydrocarbon products identification and analysis process due to the dilution of hydrocarbon peaks by the predominant solvent peak. Therefore, in this project, a custom-made Gas Chromatography (GC) analysis system was designed and implemented to identify and quantify SCF-FTS products. The FTS products were identified using two different methods. The first was through retention time matching by injecting standard solutions, and the second was through the use of the GC/MS system. The quantification of CO and CH4 was achieved by using external standards, where the CO conversion was calculated by relating the peak area of CO to the peak area of an internal standard (argon) while the CH4 selectivity was calculated by relating the peak area of CH4 to that of CO. After setting and calibrating the GC system, two reaction conditions (gas phase: 240°C, 20 bar syngas with 2:1 H2:CO molar feed ratio and for the supercritical fluids FTS (SCF-FTS): 240°C, 65 bar with 20 bar syngas partial pressure and 2:1 H2:CO molar feed ratio) were used to compare the different FTS reaction media. The comparison between the gas phase FTS and the SCF-FTS showed the following: carbon monoxide conversion was improved by 14% in the SCF-FTS, while the hydrocarbon product profile SCF-FTS showed 78% reduction in light hydrocarbons (C1 - C4) products, 35% increase in middle distillates (C11 - C22) products compared to gas phase FTS. These improvements have resulted in higher chain growth probability for the SCF-FTS (α = 0.85) compared to the gas phase FTS (α = 0.76). These results are generally in agreement with previously reported enhancement in the SCF-FTS[1].

烟草中甲霜灵的手性分离方法差异研究

对比反相液相色谱-串联质谱(RPLC-MS/MS)和超临界流体色谱-串联质谱(SFC-MS/MS)手性分离烟草中甲霜灵的差异。烟草样品经乙腈提取、盐析分层、快速滤过型净化(multi-Plug Filtration Cleanup,m-PFC)柱净化后,分别采用RPLC-MS/MS和SFC-MS/MS进行手性分离。从多个性能参数(分离效率、线性、选择性、回收率、重复性、灵敏度、基质效应等)对两种方法进行了全面比较。采用不同的分离方法,在10~500 ng/mL范围内,甲霜灵的不同异构体均可呈现良好的线性关系(R^(2)≥0.9993)。在各异构体加标浓度为0.1、0.5、2.0 mg/kg水平下,采用不同的分离方法均可获得满意的回收率(88.7%~96.2%)和良好的重复性(RSD<7.0%)。结果表明:RPLC-MS/MS和SFC-MS/MS具有互补性,均适用于手性分离和测定烟草基质中的甲霜灵。

超临界流体萃取-液相色谱/质谱法测定成人服装中的偶氮染料及其分解产物

偶氮染料作为一种广泛使用的合成染料,在环境中的稳定性和生物降解性较差,会在服装使用和废弃过程中释放出有毒的分解产物,对环境和人体健康造成潜在风险。使用超临界流体萃取-液相色谱/质谱法测定成人服装中的偶氮染料及其分解产物,有利于评估其生态和健康风险,可以提出针对性的环境保护策略,为纺织行业的可持续发展和环境保护提供参考。

超临界萃取结合分子蒸馏纯化生姜精油及其挥发性成分分析

为研究超临界萃取结合分子蒸馏纯化生姜精油的最佳工艺参数,鉴定生姜精油的挥发性成分,以舒城黄姜为原料,通过单因素试验和正交试验优化了超临界CO_(2)流体萃取(supercritical CO_(2)fluid extraction,SFE)生姜油的最佳工艺条件,考察了分子蒸馏(molecular distillation,MD)温度对分离纯化生姜精油效果的影响,并通过气相色谱-质谱联用对生姜精油的挥发性成分进行了分析。结果表明,超临界CO_(2)流体萃取结合分子蒸馏(SFE-MD)纯化生姜精油的最佳工艺条件为萃取压力24 MPa、萃取温度45℃、萃取时间2 h、分子蒸馏温度80℃,在此条件下,生姜精油的综合得率为2.53%,显著高于水蒸气蒸馏精油得率0.96%(P<0.05)。挥发性成分分析显示,α-姜烯、β-倍半水芹烯、β-红没药烯是生姜精油的主要挥发性成分,百分含量达70%以上,其中α-姜烯百分含量为42.13%,高于水蒸气蒸馏生姜精油α-姜烯百分含量40.59%。该方法绿色环保,萃取率高,精油品质好,为生姜精油的进一步研究开发提供参考。

三种柑橘类精油的GC-MS分析及抑菌活性对比

选取陈皮、柠檬和金桔这三种柑橘类植物为原料,利用超临界CO_(2)萃取法高效提取精油。采用GC-MS分析样品成分,进而探究三种精油对金黄色葡萄球菌和烟曲霉菌的抑菌活性。研究表明:柠檬精油中的醇类(3.41%)、醛类(2.55%)、酮类(2.03%)、酯类(7.17%)和除柠檬烯以外的萜烯类化合物(34.06%)含量较高,D-柠檬烯含量是这三种精油中最低的(46.52%);陈皮精油中的萜烯类(86.34%)、酚类化合物(1.82%)含量较高;金桔精油中的酸类化合物(12.71%)和D-柠檬烯(72.69%)含量较高。精油对金黄色葡萄球菌和烟曲霉菌的抑菌活性均为柠檬精油>陈皮精油>金桔精油。在这三种柑橘类精油中D-柠檬烯并非是唯一的抑菌成分,精油的抑菌活性也与除D-柠檬烯以外的抑菌成分密切相关。其中柠檬精油中含量丰富的γ-松油烯和β-蒎烯等其他抑菌成分可与D-柠檬烯协同起到有效提高精油抑菌活性的作用。该方法所提取的精油可为相关天然抑菌产品研发提供一定帮助。