Supercritical fluid extraction environmental analysis

Bayona JM (1995) Development of supercritical fluid extraction procedures for the determination of organotin compounds in sediment. In Quevauviller Ph, Maier EA, and Griepink B, eds. Quality assurance for environmental analysis, pp 465-487. Elsevier, Amsterdam. 

Applications The majority of SFE applications involves the extraction of dry solid matrices. Supercritical fluid extraction has demonstrated great utility for the extraction of organic analytes from a wide variety of solid matrices. The combination of fast extractions and easy solvent evaporation has resulted in numerous applications for SFE. Important areas of analytical SFE are environmental analysis (41 %), food analysis (38 %) and polymer characterisation (11%) [292], Determination of additives in polymers is considered attractive by SFE because (i) the SCF can more quickly permeate throughout the polymer matrix compared to conventional solvents, resulting in a rapid extraction (ii) the polymer matrix is (generally) not soluble in SCFs, so that polymer dissolution and subsequent precipitation are not necessary and (iii) organic solvents are not required, or are used only in very small quantities, reducing preparation time and disposal costs [359]. 

Studies designed to improve the determination of environmental contaminants will continue to provide refinements and improvements in the determination of acrylonitrile. The current high level of activity in supercritical fluid extraction of solid and semisolid samples should yield improved recoveries and sensitivities for the determination of acrylonitrile in solid wastes, and the compound should be amenable to supercritical fluid chromatographic analysis. Immunoassay analysis is another area of intense current activity from which substantial advances in the determination of acrylonitrile in environmental samples can be anticipated (Vanderlaan et al. 1988). 

Lopez-Avila V, Dodhiwala NS, Becker WF. 1990. Supercritical fluid extraction and its application to environmental analysis. J Chromatographic Sci 28 468-476. 

Lopez-Avila V, Beckert WF, Billets S. 1992. Supercritical fluid extraction and its application to environmental analysis. In Friedman D, ed. Waste testing and quality assurance third volume. ASTM Special Technical Publication 1075. Philadelphia, PA American Society for Testing and Materials, 141-153. 

Solid-phase extractions can reduce solvent consumption in analytical chemistry. For example, a standard procedure approved by the U.S. Environmental Protection Agency for the analysis of pesticides in wastewater requires 200 mL of dichloromethane for the liquid-liquid extraction of 1 L of water. The same analytes can be isolated by solid-phase extraction on C g-silica disks. The pesticides are recovered from the disks by supercritical fluid extraction with C02 that is finally vented into a small volume of hexane. This one kind of analysis can save 10s kg of CH2C12 per year.24... 

Supercritical fluid extraction conditions were investigated in terms of mobile phase modifier, pressure, temperature and flow rate to improve extraction efficiency (104). High extraction efficiencies, up to 100%, in short times were reported. Relationships between extraction efficiency in supercritical fluid extraction and chromatographic retention in SFC were proposed. The effects of pressure and temperature as well as the advantages of static versus dynamic extraction were explored for PCB extraction in environmental analysis (105). High resolution GC was coupled with SFE in these experiments. 

Burford MD, Hawthorne SB, Miller DJ. 1994. Analysis of volatile organics by supercritical fluid extraction coupled to gas chromatography II. Quantitation of petroleum hydrocarbons from environmental sample. J Chromatogr A 685 95-111. 

Janda V, Bartle KD, Clifford AA (1993), J. Chromat. 642 283-299. Supercritical fluid extraction in environmental analysis"... 

Preparing the sample is a key step in all biological analyses, and hair analysis is no exception to this rule. Over the last ten years, there has been an ever increasing interest in the use of supercritical fluid extraction (SFE) as an alternative to traditional methods of preparing samples. The driving force behind this development is, without doubt, the need for a simple, rapid, automated, and selective method which should also be environmentally friendly. In this context, the use of supercritical fluids fulfills these conditions, due to their unique physicochemical properties. The following is a list of advantages ... 

Morrison, J.F., MacCrehan, W.A., Selavka, C.M., Evaluation of supercritical fluid extraction for the selective recovery of drugs of abuse from hair, 2nd International Meeting on Clinical and Forensic Aspects of Hair Analysis, National Institute on Drug Abuse. Special Publication, submitted, 1995. Welch, M.J., Sniegoski, L.T., Allgood, C.C., Habram M., Hair analysis for drugs of abuse evaluation of analytical methods, environmental issues, and development of reference materials, /. Anal. Toxicol, 17(6), 389-398, 1993. 

Hawthorne SB. Miller DJ. 1987a. Directly coupled supercritical fluid extraction-gas chromatographic analysis of polycyclic aromatic hydrocarbons and polychlorinated biphenyls environmental from solids. J Chromatogr 403 63-76. 

Supercritical fluid extraction (SFE) has been applied to a broader range of samples. Generally, the applications of SFE have been developed as a faster and less solvent-intensive alternative to traditional extraction schemes. Environmental and food analysis are the main field of applications of SFE (21) however, a wide range of applications have been focused on the extraction of drugs and active compounds from different types of matrices that are commented below. 

Lopez-Avila V, Dodhiwala NS, Beckert WF. Supercritical fluid extraction and its application to environmental analysis. J Chromatogr Sci 1990 28 468—476. Tena MT, Luque de Castro MD, Valcarcel M. Systematic study of the influence of variables on the supercritical fluid extraction of pol5Tomatic hydrocarbons (PAHs). Lab Rob Autom 1993 5 255-262. 

Figure 7.9 Schematic of the layout of a typical supercritical fluid extraction system BPR, back-pressure regulator (restrictor) SPE, solid-phase extraction. From Dean, J. R., Extraction Methods for Environmental Analysis, Copyright 1998. John Wiley Sons Limited. Reproduced with permission.

Bowadt, S. and S.B. Hawthorne. 1995. Supercritical fluid extraction in environmental analysis.. Chromatogr. A 703 549-571. 

Hale and Aneiro (1997) reviewed recent progress made in improving analytical techniques for determining components of creosote in environmental media. The multiple extraction and purification steps required prior to chromatographic analysis is problematic in that compounds may be lost through volatilization or transformed through photodegradation. More efficient extraction procedures include supercritical fluid extraction, accelerated solvent, and microwave, and solid-phase extraction. Newer... 

Lohleit, M., Hillmann, R., and Baechmann, K., The use of supercritical-fluid extraction in environmental analysis, Fresenius J. Anal. Chem., 339, 470-474, 1991. 

An alternative extraction method is supercritical fluid extraction with CO2, which has been widely used in different fields of environmental analysis. The development of a suitable extraction method for organoarsenic compounds requires a systematic optimization of the parameters chamber temperature, pressure, extraction time, number of extraction steps, modifier and rinse solvent, which could influence the extraction result crucially (Tena et al., 1993). 

Ashraf-Khorassani, M Combs, M.T. Taylor, L.T. Supercritical Fluid Extraction of Inorganics in Environmental Analysis Encylopedia of Analytical Chemistry. John Wiley Sons, 2000 Vol. 4,3410-3423. 

Microwave-Assisted Solvent Extraction Pressurized Fluid Extraction Supercritical Fluid Extraction Solid-Phase Extraction Solid-Phase Microextraction. Gas Chromatography Overview, Mass Spectrometry Environmental Applications. Immunoassays Overview. Liquid Chromatography Overview Reversed Phase Size-Exclusion Liquid Chromatography-Mass Spectrometry. Pesticides. Supercritical Fluid Chromatography Overview Applications. Thin-Layer Chromatography Overview. Water Analysis Organic Compounds. 

Supercritical fluid extraction (SEE) using supercritical carbon dioxide (SC-CO2) has been successfully used for isolation of volatile nitrosamines from different matrices such as tobacco and food products. This technique presents several advantages with respect to other extraction methods (e.g., mineral oil distillation or low-temperature vacuum distillation) currently used. Thus, SEE minimizes sample handling, provides fairly clean extracts, expedites sample preparation, and reduces the use of environmentally toxic solvents. Good results have also been obtained with the use of SPE in the analysis of food matrices combining extraction with Extrelut sorbent and purification with Florisil. This method is applicable for the analysis of a range of the most widely encountered volatile N-nitrosamines, including the poorly volatile NDBA, NDBzA, and N-nitroso-N-methylaniline in various food products. Active carbon is suitable for this preconcentration step due its low cost, versatility, and easy application. 

---