共查询到20条相似文献,搜索用时 15 毫秒
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Determination of phenols in soil by supercritical fluid extraction-capillary electrochromatography 总被引:2,自引:0,他引:2
A new analytical procedure is developed to couple supercritical fluid extraction with capillary electrochromatography (SFE-CEC) to extract and determine phenols in soil. Ten phenols consisting of phenol, methylphenols (p-cresol and o-cresol), dimethylphenols (3,5-xylenol, 3,4-xylenol and 2,6-xylenol), trimethylphenol, ethylphenols (p-ethylphenol and o-ethylphenol), and o-isopropylphenol are investigated. The use of supercritical CO2 with 10% methanol as the organic modifier was found to give satisfactory extraction of alkylphenols from soil at 1200 p.s.i. and 50 degrees C for 45 min under a total extractant flow-rate of 0.2 ml/min (1 p.s.i.=6894.76 Pa). Baseline resolution was achieved for the 10 selected phenols under optimised CEC conditions at 20 kV in a mobile phase of acetonitrile-4 mM Tris, pH 7.0 (35:65) in a 45 cm (25 cm packed with 3 microm ODS) x 75 microm I.D. fused-silica capillary column. Using SFE with a 10-fold preconcentration factor, all alkyl-substituted phenols in soil can be determined with detection limits ranging from 0.0032 to 0.014 mg/kg and working range from 0.019 to 2.72 mg/kg. The SFE-CEC procedure developed has been applied successfully to determine phenols extracted from real soil sample contaminated with medical disinfectant. It will provide a rapid method for the direct determination of phenol and alkyl-substituted phenol in soils, with capability for confirmation of unknown peaks. 相似文献
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David E. Knowles Lori Nixon Erin R. Campbell Douglas W. Later Bruce E. Richter 《Fresenius' Journal of Analytical Chemistry》1988,330(3):225-228
Summary Polymers can be difficult to fully characterize by conventional chromatographic methods [i.e., gas chromatography (GC), high performance liquid chromatography (HPLC) and size exclusion chromatography (SEC)] due to temperature instability, detector incompatibility, nonvolatility, molecular weight considerations or insufficient chromatographic efficiency. Capillary supercritical fluid chromatography (SFC) offers several advantages for polymer analysis. Complex distributions can be resolved, low temperatures can be used and individual oligomers can be detected, allowing differences in molecular weight distributions to be quantitatively and qualitatively measured. In this paper, results will be shown for the analysis of various types of polymers demonstrating how changes in chromatographic parameters affect the analysis
Industrielle Anwendungen der Chromatographie mit überkritischen fluiden Phasen: Polymeranalyse相似文献
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Supercritical fluid extraction (SFE) exploits the solvation power of fluids at temperatures and pressures close to their critical point. Use of SFE with supercritical CO2 is reported for the extraction of caffeine and quinine from various plant materials and of morphine from serum. Results are compared with those obtained by extractions with subcritical methanol and tetrahydrofuran, normal organic Soxhlet extractions and solid-phase extraction. 相似文献
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Summary A combined system of pressure-programmed packed capillary supercritical fluid chromatography-mass spectrometry (SFC/MS) was
constructed using a self-soupting interface assisted by vacuum nebulizing. For the optimum operation of the SFC/MS system,
fundamental analytical conditions such as the flow rate of the mobile phase, the pump pressure and the composition of the
mobile phase were examined. The use of large packing materials indicated that the capacity factor for a sample solute is almost
constant under a given pump pressure regardless of the flow rate of the supercritical fluid. The SFC/MS system was applied
to the analysis of both water- and fat-soluble vitamins. Both types vitamins were clearly separated under basically the same
SFC conditions. High quality mass spectra of the vitamins were obtained; selected ion monitoring (SIM) traces of the vitamins
are also reported as well as their UV traces. 相似文献
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Packed-column supercritical fluid chromatography (pSFC) is a fast separation technique that combines the properties of HPLC and GC. pSFC with carbon dioxide as the mobile phase and packed silica column as the stationary phase possesses the properties of normal phase mechanism; however, the addition of modifiers to the mobile phase allows the separation of relatively polar compounds. In spite of its many positive attributes, pSFC has not been widely used in areas such as proteomics, where methods such as HPLC dominate. Packed column SFC has been extensively used in clinical and pharmaceutical laboratories, especially for separation of nonpolar and chiral drugs. This review will discuss recently published applications of pSFC, with a specific focus on its advantages and limitations for the analysis of pharmaceuticals with varying chemical properties. 相似文献
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Capillary supercritical fluid chromatography (SFC) is proving to be a viable and useful separation method for thermally labile and nonvolatile materials. As with other capillary chromatographic techniques, very fast separations can be accomplished by sacrificing total efficiency and optimizing the conditions for rapid analysis. This is achieved using short, small-bore capillary columns, increased mobile phase linear velocities and very fast pressure programming rates. These principles are demonstrated for the rapid separation of selected component systems. 相似文献
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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. 相似文献
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Sameena Ashraf Keith D. Bartle Anthony A. Clifford Robert Moulder 《Journal of separation science》1991,14(1):29-32
Capillary supercritical fluid chromatography was performed using solvent-vented injection in conjunction with a thermionic ionization detector. Mixtures of organo-nitrogen and phosphorus containing agrochemicals were chromatographed and detection of low picogram quantities was observed. 相似文献
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Bamba T Fukasaki W Kajiyama S Ute K Kitayama T Kobayashi A 《Journal of chromatography. A》2001,911(1):113-117
A high-resolution analysis of polyprenol mixtures was achieved by supercritical fluid chromatography (SFC). The separation of polyprenols was examined on an octadecylsilane-packed column with liquid carbon dioxide as the mobile phase and ethanol as modifier. Using this chromatography system, the resolution of separation (Rs) between octadecaprenol (prenol 18) and nonadecaprenol (prenol 19) was two times higher than that using conventional reversed-phase high-performance liquid chromatography. Our SFC technique allows the advantage of baseline separation of polyprenol samples containing hydrophobic components such as terpenes or fatty acids that are unfavorable for good separation. This method is very useful for the analysis of structurally close polyprenol analogues of rubber plant metabolites. 相似文献
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In order to assess the true impact of each single enantiomer of pharmacologically active compounds (PACs) in the environment, highly efficient, fast and sensitive analytical methods are needed. For the first time this paper focuses on the use of ultrahigh performance supercritical fluid based chromatography coupled to a triple quadrupole mass spectrometer to develop multi-residue enantioselective methods for chiral PACs in environmental matrices. This technique exploits the advantages of supercritical fluid chromatography, ultrahigh performance liquid chromatography and mass spectrometry. Two coated modified 2.5 μm-polysaccharide-based chiral stationary phases were investigated: an amylose tris-3,5-dimethylphenylcarbamate column and a cellulose tris-3-chloro-4-methylphenylcarbamate column. The effect of different chromatographic variables on chiral recognition is highlighted. This novel approach resulted in the baseline resolution of 13 enantiomers PACs (aminorex, carprofen, chloramphenicol, 3-N-dechloroethylifosfamide, flurbiprofen, 2-hydroxyibuprofen, ifosfamide, imazalil, naproxen, ofloxacin, omeprazole, praziquantel and tetramisole) and partial resolution of 2 enantiomers PACs (ibuprofen and indoprofen) under fast-gradient conditions (<10 min analysis time). 相似文献
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Duquesnoy E Marongiu B Castola V Piras A Porcedda S Casanova J 《Natural product communications》2010,5(12):1995-1998
Two samples (leaves and twigs) of Abies alba Miller from Corsica were extracted using supercritical CO2 and their chemical compositions were compared with those of the essential oils obtained from the same batch of plant material. In total 45 components were identified using combined analysis by GC (RI), GC-MS and 13C NMR. It was observed that the contents of monoterpenes (mainly represented by limonene, alpha-pinene and camphene) were significantly lower in the supercritical fluid extract (SFE) than in the essential oil (EO). Conversely, the proportions of sesquiterpenes were much higher in CO2 extracts than in essential oils (around 30% vs 4%). Cis-abienol, a diterpene alcohol, was identified only in SFE, and the proportions of this constituent (7.5% and 17.3%) were determined using quantitative 13C NMR since it was under estimated using the standard conditions of GC. 相似文献
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Analysis of sulphonamides using supercritical fluid chromatography and supercritical fluid chromatography-mass spectrometry 总被引:1,自引:0,他引:1
Packed-column supercritical fluid chromatography has been used for the separation of mixtures of sulphonamides on silica and amino-bonded stationary phases utilizing carbon dioxide with methanol modifier as the mobile phase. The effect of modifier concentration, column pressure and modifier identity on retention was also studied. Packed-column supercritical fluid chromatography-mass spectrometry (SFC-MS) of these mixtures utilizing both moving-belt and modified thermospray interfaces was also studied. The identification of sulphamethazine in a spiked porcine kidney extract was performed by SFC-MS using the moving-belt interface. 相似文献