摘要:

Ochratoxin A is a highly nephrotoxic mycotoxin commonly associated with cereals and cereal products. Residues of the toxin are also frequently found in animal tissues, e.g. pig kidney, when animals are fed with contaminated feed. The analysis of foodstuffs for ochratoxin A has been simplified by the introduction of immunoaffinity methods such as the Biocode ochratoxin EASI EXTRACT column. These columns contain monoclonal antibodies raised against ochratoxin A and allow purification and concentration of the toxin from a foodstuff. Analysis involves a solvent extraction stage prior to application to the ochratoxin EASI EXTRACT column, with detection of the toxin by high‐pressure liquid chromatogra‐phy. Several solvent extraction systems have been evaluated for both wheat and kidney. Percentage recoveries from spiked material ranged between approximately 35 and 80% for kidney samples and between approximately 65 and 80% for wheat samples depending on the extraction solvent used. Immunoaffinity analysis for ochratoxin A appears to be the method of choice for accurate quantification.

ISSN:0954-0105    

DOI:10.1080/09540109409354846

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Polyclonal antisera were produced in rabbits against two different synthetic immunogens, one of which incorporated 3‐phenoxybenzoic acid (PBA) while the other contained dichlorovinyl cyclopropane carboxylate (CPA). The immunogens were constructed such that the hapten was coupled to the carrier protein through a peptide bond to a six carbon spacing group (6‐amino hexanoic acid, 6‐AHA). Both the anti‐PBA and anti‐CPA antisera obtained were able to detect permethrin when used in an indirect competitive enzyme‐linked immunosorbent assay (IC‐ELISA) format. The detection limits typically obtained with both antisera were 10 mg l‐1with 50% inhibition of antibody binding (ho) at 100mg l‐1. Cross‐reactivity with the pyrethroids cyfluthrin, phenothrin and deltamethrin was observed for both antisera, the degree of which was related to the structural similarity of the compound to the immunizing hapten. Further development of the immunoassay for permethrin was examined through use of the anti‐PBA antiserum. Assay performance was improved by negative immunoaffinity chromatog‐raphy of the anti‐PBA antiserum, in which antibodies directed against the six carbon spacing group were removed. In conjunction with an avidin‐biotin amplification step, typical detection limits were 1 mg l‐1with an I50value of 15 mg l‐1. Assay performance was considerably enhanced by use of a microtitre plate coating antigen which possessed a four carbon spacing group between the hapten and carrier protein. The hapten was also coupled to the spacing group through an ester bond. Typical detection limits for permethrin were 0.5μg l‐1, with an I50value of 1 mg l‐1. This assay was also unaffected by the inclusion of methanol at concentrations of up to 10% by volume. The study indicated the potential usefulness of antibodies raised against compounds which mimic moieties present within larger hapten molecules (anti‐hapten mimic antibodies), particularly where the target analyte is not amenable to direct conjugation to a carrier protein.

ISSN:0954-0105    

DOI:10.1080/09540109409354847

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Immunoassay technology offers many advantages over conventional analytical methods for pesticide analysis in the field, and in this study enzyme‐linked immunosorbent assay (ELISA) was applied to the analysis of s‐triazine herbicides in pesticide waste and rinsate mixtures. This sample type usually contains a mixture of pesticide active ingredients, formulating agents, fertilizers and debris. Therefore it was necessary to study the effects of these potential matrix components on the ELISA. This was done by evaluating ELISA standard curve parameters in the presence of matrix components. The assay tolerated fertilizer concentrations up to 1% (w/v) in the sample and had a wide pH range (2–9). MgCl2produced effects at 0.009% (w/v) which could result in a false negative result, but all other matrix effects implied false positive results and overestimates of analyte concentration. Ionic surfactants affected the assay above 0.156% (v/v). Non‐ionic surfactants had little effect on the assay, but commercial agricultural formulations interfered with it above 0.156% (v/v). A rapid solid‐phase extraction method for s‐triazine herbicides was tested on actual rinsate samples and improved assay precision.

ISSN:0954-0105    

DOI:10.1080/09540109409354848

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Quantitative competition immunoassays with appropriate combinations of antibodies give consistent dose‐response patterns which may be used to identify and estimate amounts of cross‐reacting compounds. Previously reported methods of analyzing cross‐reaction patterns include multiple regression, principal components analysis and minimum estimates of variance (MEV). Four other techniques which are preferable in theory have been surveyed: discriminant analysis (DA), maximum likelihood estimates (MLE), classification and regression trees (CART), and computational neural networks (NN). MLE and simple back‐propagation neural networks can estimate the concentration, as well as the identity, of individual compounds. These four methods worked well with unfitted, unscaled data from monoclonal assays of triazines, phenylureas and avermectins. Immunoassays must be properly designed to provide adequate data for pattern recognition. Cross‐reactivity pattern analysis will make multi‐analyte, multi‐antibody immunoassays feasible for many applications in toxicology and hazard assessment.

ISSN:0954-0105    

DOI:10.1080/09540109409354849

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Polyclonal antibodies raised against 6,7‐dihydro‐6‐carboxyaldrin can be used to detect aldrin and dieldrin. These analytes are preferentially fat soluble. An immunoassay is described which provides a method for detecting these pesticides in milk, a fat‐rich matrix. The enzyme‐linked immunosorbent assay (ELISA) can detect aldrin/dieldrin in milk in the range 1 ng ml‐1‐5 μg ml‐1simply and reliably. The detection range differs in skimmed and semi‐skimmed milk and in cream, reflecting the differences in fat content between these samples.

ISSN:0954-0105    

DOI:10.1080/09540109409354850

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A highly sensitive enzyme‐linked immunosorbent assay (ELISA) was developed to detect alachlor in tap water samples. When it was compared with classical detection methods such as gas chromatography/mass spectrometry, the ELISA was much faster because there were no sample preparation steps and analysis time was quicker. The average recovery over a range of fortified samples was 87% and inter‐plate variation was less than 10%. The ELISA had a sensitivity of 0.017 ppb which was five times more sensitive than the EC cut‐off of 0.1 ppb, making it suitable for the large‐scale screening of tap water samples.

ISSN:0954-0105    

DOI:10.1080/09540109409354851

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A highly sensitive, competitive, enzyme‐linked immunosorbent assay (ELISA) was developed for the detection of five triazine herbicides in water samples. Low detection limits were achieved without the need to concentrate samples prior to analysis by ELISA. The limit of detection for ametryn, prometryn and prometon was 0–05 ng ml∼’ while atrazine and propazine had a detection limit of 0.2 ng ml‐1. The concentrations of analyte required to reduce zero standard absorbances by 50% (IC50) far ametryn, prometryn, prometon, propazine and atrazine were 0.18, 0.18, 0.26, 0.48 and 0.37 ng ml‐1respectively. De‐ethylatrazine and simazine had respective ICsos of 4.0 and > 25.0 ng ml‐1. Inter‐assay coefficients of variation were generally less than 10% and recoveries of triazines from fortified water samples were in the range 90–115% for all five triazine herbicides. The results demonstrate the ability of an enzyme immunoassay to detect five triazine herbicides at concentrations below or very close to the maximum concentration allowed under EC guidelines in drinking water (0.1 ng ml‐1) for individual pesticides.

ISSN:0954-0105    

DOI:10.1080/09540109409354852

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An immunofluorescence capillary electrophoresis technique is described for the detection of chloramphenicol where the analyte was allowed to compete with a chloramphenicolfluorescein conjugate for binding to polyclonal anti‐chloramphenicol antibody. The bound and unbound forms of the chloramphenicol‐fluorescein conjugate were then analyzed by capillary zone electrophoresis with laser‐induced fluorescence detection, which permitted direct quantitation of the extent of immunocomplex formation. The amount of unbound conjugate in the reaction mixture was proportional to the quantity of chloramphenicol in the sample. Using this assay, it was possible to detect concentrations as low as 0.1–0.5 ng ml‐1of chloramphenicol in a standard buffer and at least 01 ng ml‐1of chloramphenicol in milk after extraction with ethyl acetate using a simple protocol. This highly sensitive procedure was rapid, requiring less than 30min to complete. The immunofluorescence capillary electrophoresis system should be similarly applicable to the assay of a wide variety of analytes.

ISSN:0954-0105    

DOI:10.1080/09540109409354853

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A double sandwich ELISA system has been produced capable of detecting < 166 ppm bovine and ovine heat‐stable proteins in rendered animal material heated to 140°C for 1.5 h. Removal of gelatin from rendered animal material by ammonium sulphate precipitation and concentration of the remaining proteins for species testing proved to be of considerable benefit in amplification of test sensitivity.* Increased sensitivity was also obtained by judicious selection of antisera raised either against fresh’ or ‘cooked’ muscle/ tissue heat‐stable antigens.

ISSN:0954-0105    

DOI:10.1080/09540109409354854

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Common wheat (Triticum aestivum L) specific gamma (y) and omega (a) gliadins from native (unheated) and heat‐processed (pasta) samples have been purified by reverse‐phase high‐pressure liquid chromatography and used to raise polyclonal antisera in New Zealand White rabbits. The sera have been examined in both the crude and affinity‐purified (against Durum flodur gliadins) states, for reactivity and specificity against gliadins from unheated and heat‐processed common wheats. Further, the antisera have been examined for cross‐reactivity against Durum wheat (Triticum durum Desf.) and pastas and for their potential as a means of detecting the adulteration of Durum wheats and Durum wheat pasta products with common wheat species (T. aestivum). The efficacy of the antisera was evaluated using two different immunoassay formats, enzyme‐linked immunosorbant assay (ELISA) and immunoblotting.

ISSN:0954-0105    

DOI:10.1080/09540109409354855

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor