Supercritical fluid extraction immunoassay

Morrison JF, Chester SN, Reins JL. Supercritical-fluid extraction—immunoassay for the rapid screening of cocaine in hair. J Microcolumn Sep 1996 8 37-45. 

Specific extraction methods are used to prepare the analyte for immunoassay by freeing the analyte fromboth specific and nonspecific interferences. Supercritical fluid extraction has been used to decrease the amount of solvent waste generated. Solid-phase extraction has gained popularity, and many different supports are available. One promising extraction and concentration method is immunoaffinity chromatography, which will be addressed later. 

J.W. King and K.S. Nam, Coupling enzyme immunoassay with supercritical fluid extraction, in Immunoassays for Residue Analysis, ed. R.C. Beier and L.H. Stanker, American Chemical Society, Washington, DC, Chapter 34, pp. 422-438 (1996). 

Acrylonitrile metabolites have been measured in blood and urine, but, except for measurement of thiocyanate, these methods have not been developed for routine monitoring of exposed humans. Supercritical fluid extraction/chromatography and immunoassay analysis are two areas of intense current activity from which substantial advances in the determination of acrylonitrile and its metabolites in biological samples can be anticipated. The two techniques are complementary because supercritical fluid extraction is especially promising for the removal of analytes from sample material and immunoassay is very analyte-selective and sensitive (Vanderlaan et al. 1988). 

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). 

McNally et al. have applied supercritical fluid extraction chromatography to the determination of diuron and linuron in soil [442]. Schlaeppi et al. [443] have described an automated magnetic particle-based chemiluminescent immunoassay for the determination of trisulfuron in soil [462]. 

Lopez-Avila, V., C. Charan, and W.F. Beckert (1994). Using supercritical fluid extraction and enzyme immunoassays to determine pesticides in soils. Trends Anal. Chem., 13(3) 118-125. 

Nam, K.S. and J.W. King (1994). Supercritical fluid extraction and enzyme immunoassay for pesticide detection in meat products. J. Agric. Food Chem., 42(7) 1469-1474. 

Wong, J. M., Li, Q. X., Hammock, B. D. and Seiber, J. N., Method for the analysis of 4-Nitro-phenol and parathion in soil using supercritical fluid extraction and immunoassay, J. Agric. Food Chem., 39, 1802-1807, 1991. 

Stearman, G. K., Wells, M. J., Adkisson, S., and Ridgill, T., Supercritical fluid extraction coupled with enzyme immunoassay analysis of soil herbicides, Analyst, 120, 2617-2621, 1995. 

G.K. Stearman, M.J.M. Wells, S.M. Adkisson, T.E. Rid-gill, Supercritical Fluid Extraction Coupled with Enzyme Immunoassay Analysis of Soil Herbicides , Analyst, 120, 2617-2621 (1995). 

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. 

Johnson and Van Emon [57] have described a quantitative enzyme based immunoassay procedure for the determination of polychlorinated biphenyls in soils and sediments and compared the results with those obtained by a gas chromatographic method. The soil is extracted with methanol, or Soxhlet extracted or extracted with a supercritical fluid. In the case of the latter two extractants good agreement was obtained between immunoassay and gas chromatographic methods. Spiking recoveries from soil achieved ranged from 104% (Aroclor 1248) to 107% (Aroclor 1242). Detection limits were 9pg kg-1 (Aroclor 1245) and 10.5pg kg-1 (Aroclor 1242). Chlorinated anisoles, benzenes or phenols did not interfere. 

M. J. M. Wells and G. K. Stearman, Coordinating supercritical fluid and solid-phase extraction with chromatographic and immunoassay analysis of herbicides, in M. T. Meyer and E. M. Thurman, eds., Herbicide Metabolites in Surface Water and Groundwater, ACS Symposium Series 630, American Chemical Society, Washington, DC, 1996, pp. 18-33. 

Depending on the complexity of the sample matrix, a pre-cleaning step is a possible solution to remove interfering eflFects nevertheless, the choice should be a good compromise in relation to the total time and cost of analysis [33]. Supercritical fluid- [48,49], microwave-assisted- [50] or solid-phase extraction (SPE) [51-53] have been used as pre-cleaning steps prior to immunoassay. However, in certain situations, the extraction step led to a decrease in accuracy and recovery, probably due to analyte loss during clean-up/ evaporation/re-dissolution steps [53]. 

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