Enzyme-linked immunosorbent assays screening methods

Enzyme-linked immunosorbent assay (ELISA) methods for pectenotoxins are under development in several countries and a preliminary method has been reported [51-54], Silica gel thin layer chromatography (TLC) is useful to identify pectenotoxins in semipurihed samples [1,20,39] however, it is difficult to use the TLC for screening tests of toxins in crude bivalve extracts owing to the poor selectivity and sensitivity. 

Cole, R. J. Domer, J. W. Kirksey, J. W. Dowell, F. E. Comparison of visual, enzyme-linked immunosorbent assay screening, and HPLC methods in detecting aflatoxin in farmers stock peanut grade samples. Peanut Sci., 15 61-3. 1988. 

TR. Dombrowski, E.M. Thurman, and G.B. Mohrman, A first application of enzyme-linked immunosorbent assay for screening cyclodiene insecticides in ground water, in Environmental Immunochemical Methods, ed. J.M. Van Emon, C.L. Ger-lach, and J.C. Johnson, American Chemical Society, Washington, DC, pp. 148-154 (1996). 

The most commonly used screening method for HIV is an enzyme-linked immunosorbent assay, which detects antibodies against HIV-1 and is both highly sensitive and specific. False positives can occur in multiparous women in recent recipients of hepatitis B, HIV, influenza, or rabies vaccine following multiple blood transfusions and in those with liver disease or renal failure, or undergoing chronic hemodialysis. False negatives may occur if the patient is newly infected and the test is performed before antibody production is adequate. The minimum time to develop antibodies is 3 to 4 weeks from initial exposure. 

Most of the analytical methods for the analysis of pesticides in food are based on instrumental approaches based on chromatography coupled to mass spectrometry. However, a great effort of development has been paid to develop rapid screening methods based on biological methods, such as, enzyme linked immunosorbent assays (ELISA). 

Benzodiazepines are an important group of drugs with tranquilizing properties. Available immunochemical methods include radioimmunoassays (164, 165), a radioreceptor assay (166), and nonseparation immunoassays such as the widely used enzyme-monitored immunotest (EMIT) and fluorescent polarization immunoassays (167, 168). Such assays generally require sophisticated apparatus and dedicated laboratories. However, a relatively simple enzyme-linked immunosorbent assay was recently described for screening benzodiazepines in urine (169). 

Serum samples are analyzed for antibody titer. When the titer is sufficiently high, the animal is bled. Serum samples are generally screened for the presence of the antibody by enzyme-linked immunosorbent assay (ELISA). ELISA methods are discussed later in this chapter. 

Analysis of taxanes is performed almost exclusively by high-performance liquid chromatography (HPLC). Immunological techniques [enzyme-linked immunosorbent assay (ELISA), radioimmunoassay (RIA)] have found minimal use in screening human plasma and plant extracts. Such biological methods suffer from cross reactivity of several taxanes with paclitaxel and their use is thus limited in semiquantitative aspects. 

Immunoassays offer much potential for rapid screening and quantitative analysis of pesticides in food and environmental samples. However, despite this potential, the field is still dominated by conventional analytical approaches based upon chromatographic and spectrometric methods. We examine some technical barriers to more widespread adoption and utilization of immunoassays, including method development time, amount of information delivered and inexplicable sources of error. Examples are provided for paraquat in relation to exposure assessment in farmworkers and food residue analyses molinate in relation to low-level detection in surface waters and bentazon in relation to specificity and sensitivity requirements built in to the immunizing antigen. A comparison of enzyme-linked immunosorbent assay (ELISA) results with those obtained from conventional methods will illustrate technical implementation barriers and suggest ways to overcome them. 

Yeung JH, Wong JK, Park BK. Development of a screening method for anti-6 beta-hydroxycortisol antibody using an enzyme-linked immunosorbent assay (ELISA) and its applications. Methods Find Exp Clin Pharmacol 1997 19 79-86. ... 

Screening methods for Water data InFormaTion in support of the implementation of the Water Framework Directive Water Framework Directive Screening Methods/Emerging Tools Enzyme-Linked ImmunoSorbent Assays Quality Control/Quality Assurance Square Wave Anodic Stripping Voltametry... 

Douillard JY, Hoffman T, Herberman RB (1980) Enzyme-linked immunosorbent assay for screening monoclonal antibody production use of intact cells as antigen. J Immunol Methods 39 309-316... 

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