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Summary This work describes the study of a degradation curve of Oxadixyl in field-treated potato and tomato samples. The residues
were extracted using classical and supercritical fluid (SFE) extraction methods and analyzed by HRGC/ECD. The extraction techniques
were compared and the results indicate the advantages of using SFE as an alternative method for pesticide analyses in these
samples. 相似文献
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Supercritical fluid extraction (SFE) is a promising technique for the extraction of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) from environmental matrices such as contaminated sediments. The ability of SFE to solubilize many organic contaminants is well documented in industrial processes but its analytical applications were exploited just recently. In this study supercritical carbon dioxide and nitrous oxide and their mixtures with 2% methanol were used to extract 2,3,7,8-TCDD from aquatic sediments. An attractive feature of this process is that the carbon dioxide, being a virtually inert fluid, leaves no solvent residue on the processed sediment. Almost 100% of the 2,3,7,8-TCDD can be extracted from a sediment spiked with 200 μg/kg 2,3,7,8-TCDD in 30 minutes by using supercritical carbon dioxide + 2% methanol. Cleanup procedure is compared with the Soxhlet extraction procedure currently used as a standard method for extracting dioxins from sediment samples. 相似文献
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A simple method has been developed for the direct coupling of supercritical fluid extractions (SFE) with a high resolution gas chromatograph (HRGC) equipped with an electron capture detector (ECD). SFE conditions have been investigated for polychlorinated biphenyls (PCBs) from sediments in terms of mobile phase, entrainer, pressure, temperature, and mass-flow through the extractor. Dynamic leaching and static steady-state extractions were compared. Extraction efficiencies of up to 100% in less than 15 minutes have been obtained. The extracted PCBs are quantitatively transferred into a fused silica open tubular column (OTC). Determination of PCBs was tested on certified sediment from National Water Research Institute and the results agreed well with certified values. 相似文献
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The supercritical fluid extraction of polychlorinated dibenzo-p-dioxins from an incinerator fly ash sample has been investigated; supercritical nitrous oxide and its mixtures with methanol and toluene were employed as mobile phases. Recoveries of individual polychlorinated dibenzo-p-dioxins congeners were calculated from results of analysis of 13C-labeled dioxins by high resolution GC-MS employing selected ion monitoring. The extraction procedure was compared with extraction in a Soxhlet apparatus, which is currently used as a standard method for removing chlorinated dibenzo-p-dioxins from fly ash samples: the results indicated that the time required for the extraction and clean-up can be reduced from 24 to 2.5 hours/sample. Quantitative recovery of the chlorinated dibenzo-p-dioxins was achieved at μg/kg levels, the relative standard deviation was between 1.8 and 5.8%. The use of a virtually inert fluid such as pure nitrous oxide provides significant improvement over conventional extraction procedures because no solvent residue is left in the processed extract. 相似文献
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Supercritical fluid extraction (SFE) of the fluoroquinolones norfloxacin and ofloxacin from chicken breast muscles was examined. A liquid chromatography with fluorescence detection was used for the determination of the fluoroquinolones. Extraction conditions of the SFE were optimized by determining the extraction parameters to achieve a sufficiently high recovery of each fluoroquinolone in fortified-muscle samples. Recovery values for the extraction of the fluoroquinolones using the SFE ranged from 70 to 87%. Chickens were treated orally with each fluoroquinolone and their muscles were extracted at set time intervals for time-course determination of the fluoroquinolones in chickens. The SFE combined with liquid chromatographic analysis showed that the concentrations of the fluoroquinolones decreased gradually with time in the chicken muscles after oral treatment, giving a concentration less than 5 ng/ml in 120 h. No further sample cleanup procedures were required after the SFE. These results suggest that SFE method is an extraction method for the determination of norfloxacin and ofloxacin in chicken muscle. 相似文献
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J. Poustka K. Holadová J. HajšLová 《International journal of environmental analytical chemistry》2013,93(2-4):139-144
Abstract Application of supercritical fluid extraction (SFE) utilizing pure carbon dioxide for selective isolation of organophosphates from contaminated cereals has been tested. At the beginning of the experiments the extractability of added standards from an empty extraction vessel (thimble) and from various materials such as filter paper, sand, Celite and anhydrous sodium sulfate was tested to estimate the behavior of organophosphates. Further method development was carried out using a spiked sample of flour, which was analyzed within the proficiency testing for organophosphorus pesticides analysis (round 7) organized by Food Analysis Performance Assessment Scheme (FAPAS, MAFF-UK). Comparison of the SFE method with a classical method currently employed for sample preparation (i.e. extraction with acetone/methanol mixture followed by gel permeation chromatographic clean up) showed advantages of the SFE technique such as simplification of the sample preparation step and thereby significant speeding up of the determination of organophosphates in cereals. 相似文献
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Supercritical fluid extraction of mercury species 总被引:1,自引:0,他引:1
Supercritical fluid extraction was used to recover organic and inorganic mercury species. Variations in pressure, water, methanol, and chelator create methods that allowed separation of inorganic from organic mercury species. When extracted using a compromised set of extraction conditions, the order of extraction was methyl, phenyl and inorganic mercury. For the individually optimized conditions, quantitative recoveries were observed. Level as low as 20 ppb were extracted and then determined using ICP. 相似文献
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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. 相似文献
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Summary Determination of carbamate residues in tobacco samples was carried out by solid-liquid extraction (SLE) and supercritical-fluid extraction (SFE) methods, both developed for this purpose. The clean-up step was carried out on SPE-Florisil cartridges and the extracts analysed by capillary zone electrophoresis (CZE) with UV detection.The results were compared and SFE using CO2-acetone showed the best results in terms of recovery and generally higher extraction power. SFE in conjunction with CZE proved suitable for carbamate residue analysis in real tobacco samples. 相似文献
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Introduction Ginseng( Panax ginseng C. A. Meyer, Araliaceae) is one of the most valuable Chinese crude drugs and has been used widely for over 2000 years. Studies have demonstrated that ginseng can act on the central nervous system, the cardiovascular system and the endocrine system; it can enhance immune function and metabolism; it possesses a biomodulation action, anticancer effect, anti-stress and anti-ageing activities, and so on. 相似文献
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M. W. Raynor I. L. Davies K. D. Bartle A. A. Clifford A. Williams J. M. Chalmers B. W. Cook 《Journal of separation science》1988,11(11):766-775
The combination of supercritical fluid extraction, high resolution capillary supercritical fluid chromatography, and Fourier transform infrared microspectrometry is described for the separation and identification of polycyclic aromatic hydrocarbons in a coal tar pitch. The variable solvating power of the supercritical fluid was utilized to selectively fractionate the sample. The fluid extract was decompressed through a frit restrictor into the sample cavity of a cooled microvalve injector, where the analytes were deposited and concentrated for subsequent chromatographic analysis. Several of the analytes separated in the chromatograph were collected on a potassium bromide disc at a solvent elimination inter-face for subsequent infrared analysis involving the use of an infra-red microscope accessory. The spectra obtained show the power of this detection technique for distinguishing between isomers. 相似文献