Enzyme-linked immunosorbent assay technique

The use of europium chelates, with their unusually long fluorescence decay times, as labels for proteins and antibodies has provided techniques that are referred to as time-resolved fluoroimmunoassays (TRFIA). Fluorophores as labels for biomolecules will be the topic of Sect. 3. Nevertheless, TRFIAs always have to compete with ELISA (enzyme-linked immunosorbent assays) techniques, which are characterized by their great versatility and sensitivity through an enzyme-driven signal amplification. Numerous studies have been published over the past two decades which compare both analytical methods, e.g., with respect to the detection of influenza viruses or HIV-1 specific IgA antibodies [117,118]. Lanthanide luminescence detection is another new development, and Tb(III) complexes have been applied, for instance, as indicators for peroxidase-catalyzed dimerization products in ELISAs [119]. 

Holmstrom et al. (1989b) evaluated the long-term inhalation effects of formaldehyde exposure to immune function in female Sprague-Dawley rats exposed to 12.6 ppm formaldehyde for 6 hours/day, 5 days/week for 22 months. After 22 months of formaldehyde exposure, the rats were inoculated subcutaneously with Pneumovax (Merck Sharpe and Dohme) and antitetanus vaccine (National Bacteriological Laboratory). Animals were sacrificed at 21-25 days after vaccination. Blood samples were collected from each animal before vaccination and just prior to sacrifice. Tlie blood was analyzed for response to Pneumovax and tetanus vaccination using an enzyme-linked immunosorbant assay technique. The results indicated... 

Current methodology frequently applies methods for the analysis of PUHs in soil involving classic LSE with organic solvents at room temperature. Henze et al. performed the extraction of linuron and its metabolites from soil samples by LSE with acetone followed by SPE cleanup. Performing LSE, Liegeois et al. proposed a quantification procedure for isoproturon in soil samples using an enzyme-linked immunosorbent assay technique. Perez et al. isolated chlorotoluron, isoproturon. 

All protein determination methods described are not absolute and demand some form of calibration. The Kjeldahl s method remains the only official method currently available for calibration purposes and maintains its position as the most frequently used technique for the determination of organic nitrogen in food products. CE and immunochemical (enzyme-linked immunosorbent assay) techniques are most suitable for rapid separation and quantification of individual food proteins and are promising for widespread use in food protein analysis due to their high sensitivity, specificity, and simplicity of operation. There are numerous methods for the evaluation of the nutritional quality of food proteins. 

Substitution. Obviously, if it is possible to perform the experiment without the use of radioactive substances, then all exposure is avoided. For example, the ELISA (Enzyme-linked immunosorbant assay) technique has replaced that of RIA (Radioimmuno assay) for many procedures. 

MacroHdes are obtained by controUed submerged aerobic fermentations of soil microorganisms. Although species of Streptomjces have dominated, species of Saccharopoljspora Micromonospora and Streptoverticillium are also weU represented. New techniques such as enzyme-linked immunosorbent assay (ELISA) based assays may prove beneficial for discovering new stmctures (464). 

Several heterogeneous electrochemical enzyme immunoassays have been demonstrated. These are based on the enzyme-linked immunosorbent assay (ELISA) technique... 

H.A. Moye, Enzyme-linked immunosorbent assay (ELISA), in Pesticide Residues in Foods Methods, Techniques, and Regulations, W.G. Fong, H.A. Moye, J.N. Seiber, and J.P. Toth (eds), Wiley, New York, Chapt. 6 (1999). 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

Oxime carbamates are not directly amenable to gas chromatography (GC) because of their high thermal instability, which often leads to their breakdown at the injection port or in the column during analysis. Analysis of oxime carbamates by GC with sulfur detection or flame photometric detection involves oxidation of the intact insecticides or alkaline hydrolysis to form the more volatile but stable oxime compound. Enzymatic techniques have been reported for the analysis of these compounds. Enzyme-linked immunosorbent assay (ELISA) has been used to determine aldicarb and its sulfone and sulfoxide metabolites and methomyl in water, soil, and sediment samples. 

Additionally it has been our experience that mass spectrometry as a routine detection/identification technique for bacteria is not well received by microbiologists and clinicians who prefer less expensive, less complicated approaches to bacterial typing and identification, such as methods based on polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISA). For that reason we have adapted our MS approach to serve as a means of biomarker discovery that feeds candidate proteins or leads into development as PCR targets or other immunoassay techniques. 

A. Heginbotham, V. Millay, M. Quick, The use of immunofluorescence microscopy (IFM) and enzyme linked immunosorbent assay (ELISA) as complementary techniques for protein identi fication in artists materials, J. Am. Inst. Cons., 45, 89 105 (2006). 

Biological techniques, e.g., immunoassays, are among the most sensitive analytical methods, but are limited by the availability of the specific antisera and are subject to cross-reactivity. Huang et al. [36] employed an enzyme-linked immunosorbent assay (ELISA) for determination of estradiol, its conjugates, and ethynylestradiol in wastewaster treatment plant effluents (see Table 4). The reported limit of detection (LOD) of 0.1 ng L 1 reflects the sen-... 

Enzyme-Linked Immunosorbent Assay (ELISA) An immunological technique used to quantify the amount of antigen or antibody in a sample such as blood plasma or serum. 

Enzyme labels are usually associated with solid-phase antibodies in the technique known as enzyme-linked immunosorbent assay (ELISA). There are several variants of this technique employing both competitive and non-competitive systems. However it is best used in combination with two monoclonal antibodies in the two-site format in which an excess of antibody is bound to a solid phase such as a test-tube or microtitre plate the test antigen is then added and is largely sequestered by the antibody (Figure 7.12). After washing... 

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