Dioxin supercritical fluid extraction

Von Bavel et al. [55] have developed a solid phase carbon trap (PX-21 active carbon) for the simultaneous determination of polychlorodibenzo-p-dioxins and polychlorodibenzofurans also polychlorobiphenyls and chlorinated insecticides in soils using superfluid extraction liquid chromatography for the final determination. Supercritical fluid extraction with carbon dioxide has been applied to the determination of dioxins in soil [114],... 

As discussed in section 5.6.1.4 a solid phase carbon trap has been used in conjunction with supercritical fluid extraction liquid chromatography for the simultaneous determination of organochlorine insecticides, polychlorobiphenyls, polychlorodibenzo-p-dioxins and polychlorodibenzofurans in soils [19]. 

Environmental applications of SFE appear to be the most widespread in the literature. A typical example is the comparison of extraction efficiency for 2,3,7,8 -tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) from sediment samples using supercritical fluid extraction and five individual mobile phases with Soxhlet extraction was made (101). The mobile phases, carbon dioxide, nitrous oxide, pure and modified with 2% methanol as well as sulfur hexafluoride were examined. Pure nitrous oxide, modified carbon dioxide and modified nitrous oxide systems gave the recoveries in the acceptable range of 80 to 100%. Carbon dioxide and sulfur hexafluoride showed recoveries of less than 50% under identical conditions. Classical Soxhlet recoveries by comparison illustrated the poorest precision with average extraction efficiencies of less than 65%. Mobile phase choice, still as yet a major question in the science of supercritical fluid extraction, seems to be dependent upon several factors polarity of the solute of interest, stearic interactions, as well as those between the matrix and the mobile phase. Physical parameters of the solute of interest, as suggested by King, must also be considered. Presently, the science behind the extraction of analytes of interest from complex matrices is not completely understood. 

Alexandrou N, Miao Z, Colquhoun M, et al. 1992. Supercritical fluid extraction and cleanup with capillary GC-ion trap mass spectrometry for determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in environemental samples. J Chromatogr Sci 30(9) 335-382. 

Alexandrou N, Pawliszyn JB. 1990. Supercritical fluid extraction for the rapid determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in municipal incinerator fly ash [Abstract]. New York, NY 41st Pittsburgh Conference and Exposition on Analytical Chemistry and applied chemistry. 

Lindstrdm G, van Bavel B, Karlsson MJL, Rappe C, Hardell L (1995), Organohalogen Compounds 23 27-30. The use of supercritical fluid extraction (SFE) as a sample preparation method in the analyses of PCDD, PCDF and PCB in human tissue", Eds. Dioxin 95 Secretariat, Edmonton, Kanada ISBN 3-928379-13-5... 

Nam KS, Kapila S, Yanders AF, Puri RK (1990), Chemosphere 20 873-880.. .Supercritical fluid extraction and cleanup procedures for determination of xenobiotics in biological samples" Onuska FI, Terry KA (1989), HRC CC12 357-361.. .Supercritical fluid extraction of 2,3,7,8-tetrachlorodibenzo-p-dioxin from sediment samples"... 

Onuska FI, Terry KA (1991), HRC CC 14 829-834.. .Supercritical fluid extraction of polychlorinated dibenzo-p-dioxins from municipal incinerator fly ash" van Bavel B, Hartonen K, Riekkola ML, Rappe C (1992), Organohalogen Compounds 8 15-18.. .Optimization of supercritical fluid extraction of PCDD/PCDFs and PCBs from fly ash", Eds. Finnish Institute of Occupational Health, Helsinki, Finnland ISBN 951-801-932-0... 

N. Alexandrou and J. Pawliszyn, Supercritical Fluid Extraction for the Rapid Determination of Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans in Municipal Incinerator Fly Ash, Paper No. 548, The Pittsburgh Conference and Exposition on Analytical Chemistry and Applied Spectroscopy, New York, New York, March 1990. 

See also Dioxins. Extraction Solvent Extraction Principles Supercritical Fluid Extraction. Food and Nutritional Analysis Antioxidants and Preservatives Pesticide Residues Mycotoxins Packaging Materials. Gas Chromatography Overview. Hormones Steroids. 

PCB phase diagrams with carbon dioxide Effect of temperature and pressure on extraction of PCB and polyaromatic hydrocarbons Combination of solid-phase carbon trap with supercritical fluid chromatography for PCB, pesticides, polychlorodibenzo-p-dioxins and polychlorofurans... 

Onuska and Terry [222] used supercritical fluid chromatography to extract dioxins from soil. 

The industrial research efforts on coffee decaffeination, spice extraction, and flavors concentration are, to a great extent, shrouded by the cloak of proprietary security, but the investigations of the use of supercritical fluids to treat various waste streams is reasonably well publicized. Most familiar, perhaps, is the supercritical waste water detoxification process developed by Modar Inc. This is potentially attractive for detoxifying refractory chemicals such as polychlorinated biphenyls, dioxin, and other toxic materials (Anon., 1982 Modell, 1982). In the Modar process, the toxic chemicals are homogeneously reacted with oxygen in supercritical water, the solvent for the organics and the oxygen. The main feature of the process is a chemical reaction discussed in more detail in chapter 11. 

One way of improving SFE efficiency is by using a more suitable SF to extract the target analyte. Unfortunately, the choice of fluids other than CO, is restricted by the desire to have reasonable critical parameter values and costs, chemical inertness, low toxicity and little environmental impact. The use of supercritical N2O has proved to increase the extraction efficiency for high-molecular weight PAHs and chlorinated dibenzo-p-dioxins from fly ash and sediment [52]. This extractant, however, does not always improve the extraction efficiency [53] also, it can be explosive in the presence of reactive organics. Other polar fluids such as CHCIF, (Freon-22) have exhibited increased efficiency in the extraction of nitrated and non-nitrated PAHs from particulate matter in diesel exhaust [54]. Freon-22 has also been found to allow significantly fast and effective extraction of... 

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