Water analysis immunoassay

Sulfonylureas are not directly amenable to gas chromatography (GC) because of their extremely low volatility and thermal instability. GC has been used in conjunction with diazomethane derivatization, pentafluorobenzyl bromide derivatization, and hydrolysis followed by analysis of the aryl sulfonamides. These approaches have not become widely accepted, owing to poor performance for the entire family of sulfonylureas. Capillary electrophoresis (CE) has been evaluated for water analysis and soil analysis. The low injection volumes required in CE may not yield the required sensitivity for certain applications. Enzyme immunoassay has been reported for chlorsulfuron and triasulfuron, with a limit of detection (LOD) ranging from 20 to 100 ng kg (ppt) in soil and water. 

Aga D.S. and E.M. Thurman (1997). Environmental immunoassays Alternative techniques for soil and water analysis. American Chemical Society Symposium Series 657 1-20. 

Bran, E.M., M. Garces-Garcia, M.J. Banuls, et al. 2005. Evaluation of a novel malathion immunoassay for groundwater and surface water analysis. Environ. Sci. Technol. 39 2786-2794. 

D.S. Aga, E.M. Thnrman, Environmental Immunoassays Alternative Techniques for Soil and Water Analysis , in Immunochemical Technology for Environmental Applications, eds. D.S. Aga, E.M. Thnrman, ACS S) -posinm Series 657, American Chemical Society, Washington, DC, 1-20,1997. 

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See also Archaeometry and Antique Analysis Dating of Artifacts. Bioassays Ovenriew. Drug Metabolism Metabolite Isolation and Identification Isotope Studies. Fertilizers. Food and Nutritional Analysis Meat and Meat Products. Immunoassays, Techniques Radioimmunoassays. Isotope Dilution Analysis. Pesticides. Pharmaceutical Analysis Drug Purity Determination. Process Analysis Overview. Radiochemical Methods Pharmaceutical Applications. Water Analysis Industrial Effluents. 

See also Immunoassays, Techniques Radioimmunoassays. Isotope Dilution Analysis. Radiochemical Methods Radiotracers. Titrimetry Overview. Water Analysis Overview. 

Immunological methods Methods such as the enzyme-linked immunoassays and radio immunoassays have wide application in the clinical field but are not suitable for water analysis because of their high detection limit. 

Immunochemical determination seems to be especially suited to the screening of large numbers of samples (e.g., water and soil analyses). Immunoassays are well suited for the analysis of the smallest sample volumes (e.g., in fog water analysis) because they allow analysis without sample preparation in a few microliters [90]. In critical... 

An enzyme immunoassay technique has been employed for measuring endosulfan and its degradation products (i.e., endosulfan diol, endosulfan sulfate, endosulfan ether, and endosulfan lactone) in water at 3 ppb (Chau and Terry 1972 Musial et al. 1976). However, this technique is not currently in use in environmental residue analysis. Further research into this technique could produce a rapid, rehable, and sensitive method for identifying contaminated areas posing a risk to human health. No additional methods for detecting endosulfan in environmental media appear to be necessary at this time. However, methods for the determination of endosulfan degradation products are needed. 

Sample preparation techniques vary depending on the analyte and the matrix. An advantage of immunoassays is that less sample preparation is often needed prior to analysis. Because the ELISA is conducted in an aqueous system, aqueous samples such as groundwater may be analyzed directly in the immunoassay or following dilution in a buffer solution. For soil, plant material or complex water samples (e.g., sewage effluent), the analyte must be extracted from the matrix. The extraction method must meet performance criteria such as recovery, reproducibility and ruggedness, and ultimately the analyte must be in a solution that is aqueous or in a water-miscible solvent. For chemical analytes such as pesticides, a simple extraction with methanol may be suitable. At the other extreme, multiple extractions, column cleanup and finally solvent exchange may be necessary to extract the analyte into a solution that is free of matrix interference. 

Structurally related compounds may cross-react with the antibody, yielding inaccurate results. In screening for the herbicide alachlor in well water by immunoassay, a number of false positives were reported when compared with gas chromatography (GC) analysis. A metabolite of alachlor was found to be present in the samples and it was subsequently determined that the cross-reactivity by this metabolite accounted for the false-positive results. On the other hand, cross-reactivity by certain structural analogs may not be an issue. For example, in an assay for the herbicide atrazine, cross-reactivity by propazine is 196% because of atrazine and propazine field use... 

For pesticide residue immunoassays, matrices may include surface or groundwater, soil, sediment and plant or animal tissue or fluids. Aqueous samples may not require preparation prior to analysis, other than concentration. For other matrices, extractions or other cleanup steps are needed and these steps require the integration of the extracting solvent with the immunoassay. When solvent extraction is required, solvent effects on the assay are determined during assay optimization. Another option is to extract in the desired solvent, then conduct a solvent exchange into a more miscible solvent. Immunoassays perform best with water-miscible solvents when solvent concentrations are below 20%. Our experience has been that nearly every matrix requires a complete validation. Various soil types and even urine samples from different animals within a species may cause enough variation that validation in only a few samples is not sufficient. 

From Figure 9 it can be concluded that the sensitivity of the assay is adequate to screen water samples for the presence of atrazine at a MAC value of 0.1 ppb. In a preliminary experiment 10 river water samples were screened for the presence of atrazine. In eight out of 10 an immunological response corresponding to atrazine levels greater than 0.1 ppb could be confirmed by GC-MS analysis. The other two samples contained atrazine at levels below 0.1 ppb (both with the enzyme immunoassay as with the GC-MS analysis). 

Several qualitative and quantitative immunochemical methods for CAP analysis in biological matrices of animal origin have been described [101,102, 104,105] (see Table 3). Van de Water et al. [ 102] described an ELISA that detected CAP in swine muscle tissue with an IC50 value of 3 ng mL1. This immunoassay was improved and subsequently optimized incorporating the streptavidin-biotin amplification system. There are also several commercially available test kits (see Table 4). RIDASCREEN is a competitive enzyme immunoassay for the quantitative analysis of CAP residues in milk, eggs, and meat in a microtiter plate. The measurement is made photometrically, obtaining a LOD of 100 ng L 1 in meat and eggs and 150 ng L 1 in milk. The test has been also applied to the analysis of tetracyclines. 

Brady J.F., J. Turner, and D.H. Skinner (1995). Application of a triasulfuron enzyme immunoassay to the analysis of incurred residues in soil and water samples. Journal of Agricultural and Food Chemistry 43 2542-2547. 

The test kit is based on immunoassay techniques and the method takes about 10 minutes to provide an analysis. A unique tag, permanently attached to the polymer, changes the color of special test strips exposed to ppm levels of polymer. The strips indicate the amount of tagged polymer that is present, without interference from other additives and contaminants. This technology is not currently available for continuous inhibitor detection, but given the importance of AH Organic Programs, there is little doubt that further developments will take place. The Water Additives Division of Great Lakes Chemical Corp. have also recently introduced a similar simple and accurate immunoassay test for the detection of Belclene 200 antiscalent. 

The three main categories of new analytical methodology are extraction technology, separation and detection technology, and immunoassay analysis. The majority of recent work has focused on the analysis of water samples for triazine herbicides and their metabolites, so this review is heavily weighted in that arena. 

The first application of immunoassay methodology for residue chemistry was in the analysis of water. Much of this effort was devoted to the analysis of -triazine herbicides, primarily atrazine. Many researchers studied the feasibility of immunoassays and restricted their analyses to field samples fortified in the laboratory (Bushway et al., 1988 Wittmann and Hock, 1989 Rubio et al., 1991 Giersch et al., 1993b Lawruk et al., 1993 Dinelli et al., 1995 Rodolico et al., 1997) or to reagent water fortified in the laboratory (Lentza-Rizos, 1996). 

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