超临界萃取川芎精油的GC-MS分析

不同压力和温度条件下超临界萃取所得川芎精油的收率不同,通过气相色谱-质谱联用对精油的挥发性成分进行分析,结果表明不同条件下超临界萃取所得川芎精油的主要挥发性成分相似,但其质量分数有一些差别.     

萃取淫羊藿挥发油的实验与分析

报道了用正交实验法研究超临界萃取淫羊藿挥发性成分的条件;结果显示最佳萃取条件为萃取压力30 MPa,萃取温度40℃,萃取时间1 h。按对结果影响大小依次排列为:萃取压力→萃取温度→萃取时间,在最佳条件下萃取挥发油,收率为2.7%;并用气相色谱-质谱联用技术分析了淫羊藿挥发油的化学成分,从中确认出43种化学成分,用峰面积归一化法通过化学工作站数据处理系统得出各化学成分在挥发油中的质量分数;其中主要成分为薄荷醇、1,2-二甲氧基-4-(2-丙烯基)-苯、5-(1-丙烯基)-1,3-苯并间二氧杂环戊烯、3,5-二甲氧基-甲苯、冰片、十五(碳)烷、1,2,3-三甲氧基-5-甲苯、外-葑醇、2,6,6-三甲基-2,4-环庚二烯-1-酮、2-莰酮等。     

Improved supercritical fluid extraction of sulphonamides

Summary Different ways used for enhancing the yield of sulphonamides leached from solid supports are reported. Supercritical CO₂ and methanol-modified CO₂ were used as extractants of the target analytes and the impregnation of the solid sample with buffer, derivatization of the analytes and ion-pair formation were assessed. Only the sulphonamide/tetramethyl-ammonium ion-pairs are quantitatively extracted from the solid supports using pure supercritical CO₂, while the other modifications and the presence of a cosolvent lead to recoveries lower than 30% for most of the analytes. Individual separation/quantitation of the analytes was performed off-line using a liquid chromatograph.     

Supercritical fluid extraction of Kava lactones from Kava root and their separation via supercritical fluid chromatography

Summary Seven Kava lactones were extracted from Kava root using both pure and 15% ethanol modified CO₂. Most of the Kava lactones were extracted employing 100% CO₂ with an efficiency greater than 90% relative to conventional solvent extraction using organic solvents. Extraction efficiency did not increase significantly when using 15% ethanol-modified CO₂ as an extraction fluid. Separation of extracted Kava lactones was obtained using various packed columns and methanol-modified CO₂. An optimized separation was achieved using either an amino or protein C₄ column at 125 atm and 80°C. Semi-preparative separation of Kava lactones was also obtained using two columns connected in series.     

茵陈挥发油的超临界CO2萃取法与水蒸气蒸馏法提取的比较

采用超临界CO2萃取法与水蒸气蒸馏法从菌陈中提取挥发油，用GC－MS法测定其化学成分和相对含量，对两种提取方法所得的挥发油进行比较，水蒸气蒸馏法提取菌陈挥发油的产率为0．03％（w），主要成分为匙叶桉油烯醇、吉玛烯D、反式－石竹烯、2，4－戊二炔苯、β－金石欢烯等；超临界CO2萃取法提取的产率为0．15％(w)，主要成分为百里酚、β－红没药烯、2－异丙基－4－甲基－1－甲氧基苯、异百里酚、2－特丁基－4－（2，4，4－三甲基戊基）苯酚、β－杜松烯等。     

肉桂挥发油的超临界CO2萃取法与水蒸气蒸馏法提取的比较分析

采用超临界CO2萃取法与水蒸气蒸馏法从肉桂中提取挥发油,用GC-MS法测定其化学成分和相对含量,对两种提取方法所得的挥发油进行比较,水蒸气蒸馏提取肉桂挥发油的产率为1％(ω),主要成分为肉桂醛、α-芹子烯、α-（王古）Ba烯、δ-杜松烯;超临界CO2萃取法提取的产率为1．5％(W),主要成分为肉桂醛、α-玷圯烯、α-依兰油烯、δ-杜松烯等。     

Quantitative analysis of polymer additives in low density polyethylene using supercritical fluid extraction/supercritical fluid chromatography

Analysis of low concentration polymer additives has been a challenging problem. The commonly used methods of analysis involve the initial extraction of polymer additives with solvents, often in a Soxhlet apparatus, followed by liquid, size exclusion, or gas chromatography. This paper describes the on-line super-critical fluid extraction (SFE)-supercritical fluid chromatographic (SFC) determination of different additives from low density polyethylene. Cryogenic collection was used as an interface between SFE and SFC to focus the extraction eluate before transfer to an analytical SFC column for quantitative analysis.     

Application of supercritical fluid extraction and supercritical fluid chromatography to the production of taxanes as anti-cancer drugs

The supercritical fluid extraction (SFE) of taxicin from the dried needles of the English yew tree, Taxus baccata is described. Analysis by supercritical fluid chromatography (SFC) and proton NMR spectroscopy was used to confirm identity and purity. The extraction efficiency of SFE is comparable with that obtained using liquid solvents. Such taxanes may be used semi-synthetically to prepare potential anti-cancer drugs.     

Characterization of Semtex by supercritical fluid extraction and off-line GC-ECD and GC-MS

Researchers using electron capture for the detection of explosive vapors currently claim the ability to detect the presence of RDX in Semtex – a plastic explosive comprising hexahydro-1,3,5-trinitro-1,3,5-triazane (RDX) in a matrix of styrene-butadiene copolymer and hydrocarbon oil. The vapor pressure of RDX at room temperature is 0.006 ppb, and therefore well below the detection limit of electron capture detection (ECD). The positive response generated by ECD is, consequently, not from the presence of RDX, but from some other component. This paper describes the extraction and identification of several compounds in Semtex, along with the determination of which is responsible for the positive response of an ECD-based detector. From the results of supercritical fluid extraction and off-line gas chromatography combined with electron capture and mass spectrometric detection, it has been concluded that ethylene glycol dinitrate is the component responsible for the positive ECD response. This conclusion is based on the requirements necessary for ECD detection, i.e. electronegativity, and a sufficient vapor pressure. The other compounds present were eliminated as possible choices because they either can not be detected by an ECD or do not have sufficient vapor pressure under ambient conditions.     

Simplex optimization of extraction of soybean oil by supercritical pentane

Summary Fractional factorial designs were used to estimate the relative significance of the effects of the variables on the extraction of soybean oil by supercritical pentane. Product recovery depends upon the pressure and the extraction time employed as well as on the size of the bean flour. On the other hand, the effect of temperature on the extraction process was negligible within the limits investigated. A modified simplex method was then used to determine optimum conditions for the most important variables to maximize product recovery. The extract obtained by SFE was compared to that obtained by a conventional extraction method.     

A new strategy for supercritical fluid extraction of copper ions

Complexation combined with supercritical fluid extraction was used to extract Cu²⁺. The effects of pressure, temperature, and total volume of CO₂ on the efficiency of extraction were systematically investigated. The extraction recovery was low (57.32%) only by pure supercritical CO₂. Addition of a suitable amount of methanol (v/v=5%) to supercritical CO₂ could enhance the extraction of Cu²⁺ (72.69%, relative standard deviation (R.S.D.)=2.12%, n=3), and the recovery increased largely (90.52%, R.S.D.=2.20%, n=3) in the presence of nonionic surfactant Triton X-100. Reverse micelle formation is presented as a new strategy of improving the extraction of metal ions with supercritical CO₂ in this paper.     

Sampling considerations in supercritical fluid chromatography

Summary Packed column supercritical fluid chromatography, like HPLC, utilizes a sample loop to introduce materials onto the column for analysis. Unlike HPLC the mobile phase in SFC cannot be used to dissolve the sample. In practice, this causes a solvent peak, which can create a problem in the chromatographic interpretation. This paper describes one approach to solving this problem. A valving scheme is used to extract materials with the supercritical CO₂ mobile phase and introduce them onto the column with no external handling. The viability of this method is demonstrated and separations of the CO₂ extracts for several materials are shown on various columns. Comparisons are made for coal and coffee extracts using this on-line method and conventional off-line CH₂Cl₂ extracts. Advantages of the on-line procedure as they apply to chromatography and high information detectors are also discussed.     

On-line coupled supercritical fluid extraction and chromatography for the determination of thiolcarbamate herbicides in soil matrix

Supercritical fluid extraction (SFE) was on-line coupled with supercritical fluid chromatography (SFC) for the determination of thiolcarbamate herbicides in soil matrix. Inert ODS-silica gel packings were used as a trap column for an interface between SFE and SFC and as an analytical column for the satisfactory separation of extracts. Thiolcarbamate herbicides could be extracted satisfactorily from the soil matrix, which had different characteristics. The results indicated that the proposed system was useful for the rapid determination of thiolcarbamate herbicides in soil matrices.     

Analytical supercritical fluid extraction of Chinese herbal medicines

Summary An analytical supercritical fluid extraction (SFE) technique, followed by GC/MS, was developed to separate and determine the volatile components in Chinese herbal medicine. Three kinds of herbs, frankincense, myrrh, andEvodia rutaecarpa were extracted and analyzed. The extraction was carried out using supercritical fluid CO₂ at 20 MPa and 50°C. The main factors affecting the efficiency and selectivity of the extraction are discussed. The results revealed the potential of supercritical fluid extraction as an analytical procedure for the study of medicinal plants.     

Direct coupling of capillary supercritical fluid chromatography with supercritical fluid extraction using modified carbon dioxide

Capillary supercritical fluid chromatography has been directly coupled with supercritical fluid extraction using modified carbon dioxide. The mixed fluids were prepared with a single pump on-line mixing system. The most important step in the SFE-SFC interface was the elimination of the modifier solvent. This was achieved by use of a coupled trap, 0.1 mm i.d. and 0.53 mm i.d. capillary tubing connected in series, with the collected solutes refocused on the second (0.53 mm i.d.) trap before transfer into the separation column. This enabled complete elimination of various modifier solvents and high efficiency collection of the solutes. The effect of the modifier on trapping efficiency was investigated using methanol, ethanol, dichloromethane, hexane, and toluene at a variety of concentrations. n-Eicosane was, for example, trapped quantitatively by modified carbon dioxide containing up to 13 % (w/w) methanol. The use of the technique has been demonstrated by selective extraction of n-paraffins, fatty acid methyl esters, and alcohols from a silica matrix; the effect of different modifiers on the extraction of a mixture of pesticides from soil has also been investigated.     

Comparison of supercritical fluid extraction and liquid-liquid extraction for isolation of selected pesticides stored in freeze-dried water samples

Summary The stability of freeze-dried water samples spiked with eight agrochemicals (atrazine, simazine, linuron, carbaryl, propanil, fenitrothion, parathion and fenamiphos) were examined to evaluate their suitability as candidate reference materials for their determination in water samples. In addition, two different extraction procedures, liquid-liquid and supercritical fluid extraction, were compared for the isolation and trace enrichment of target analytes from freeze-dried water samples. Final analytical determinations were by gas chromatography-nitrogen phosphorus detection and electronic impact mass spectrometry, and by liquid chromatography-diode array detection. The whole methodology developed in this paper permitted the determination of pesticides spiked in water at levels varying from 0.03 to 6.9 g L^–1.