Determination of ochratoxin A in currants, raisins, sultanas, mixed dried fruit, and dried figs by immunoaffinity column cleanup with liquid chromatography: interlaboratory study. 2003

Susan J MacDonald, and Sharron Anderson, and Paul Brereton, and Roger Wood
Central Science Laboratory, Sand Hutton, York, YO41 1LZ, United Kingdom. s.macdonald@csl.gov.uk

An interlaboratory study was performed on behalf of the Food Standards Agency to evaluate the effectiveness of an affinity column cleanup liquid chromatographic (LC) method for the determination of ochratoxin A in a variety of dried fruit at European regulatory limits. To ensure homogeneity before analysis, laboratory samples are normally slurried with water in the ratio of 5 parts fruit to 4 parts water, and test materials in this form were used in the study. The test portion was extracted with acidified methanol. The extract was filtered, diluted with phosphate-buffered saline, and applied to an affinity column. The column was washed and ochratoxin A was eluted with methanol. Ochratoxin A was quantified by reversed-phase LC. The use of post-column pH shift to enhance the fluorescence of ochratoxin A by the addition of 1.1 M ammonia solution to the column eluant is optional. Determination was by fluorescence. Currants, sultanas, raisins, figs, and mixed fruit (comprising dried pineapple, papaya, sultanas, prunes, dates, and banana chips), both naturally contaminated and blank (very low level), were sent to 24 collaborators in 7 European countries. Participants were asked to spike test portions of all test samples at a level equivalent to 5 ng/g ochratoxin A. Average recoveries ranged from 69 to 74%. Based on results for 5 naturally contaminated test samples (blind duplicates) the relative standard deviation for repeatability (RSDr) ranged from 4.9 to 8.7%, and the relative standard deviation for reproducibility (RSDR) ranged from 14 to 28%. The method showed acceptable within- and between-laboratory precision for all 5 matrixes, as evidenced by HORRAT values <1.3.

UI MeSH Term Description Entries
D007120 Immunochemistry Field of chemistry that pertains to immunological phenomena and the study of chemical reactions related to antigen stimulation of tissues. It includes physicochemical interactions between antigens and antibodies.
D007202 Indicators and Reagents Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499) Indicator,Reagent,Reagents,Indicators,Reagents and Indicators
D009793 Ochratoxins Isocoumarins found in ASPERGILLUS OCHRACEUS and other FUNGI. Ochratoxin contaminated FOOD has been responsible for cases of FOODBORNE DISEASES. Ochratoxin
D002138 Calibration Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output. Calibrations
D002846 Chromatography, Affinity A chromatographic technique that utilizes the ability of biological molecules, often ANTIBODIES, to bind to certain ligands specifically and reversibly. It is used in protein biochemistry. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Chromatography, Bioaffinity,Immunochromatography,Affinity Chromatography,Bioaffinity Chromatography
D002853 Chromatography, Liquid Chromatographic techniques in which the mobile phase is a liquid. Liquid Chromatography
D005638 Fruit The fleshy or dry ripened ovary of a plant, enclosing the seed or seeds. Berries,Legume Pod,Plant Aril,Plant Capsule,Aril, Plant,Arils, Plant,Berry,Capsule, Plant,Capsules, Plant,Fruits,Legume Pods,Plant Arils,Plant Capsules,Pod, Legume,Pods, Legume
D012996 Solutions The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed) Solution
D013050 Spectrometry, Fluorescence Measurement of the intensity and quality of fluorescence. Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D013056 Spectrophotometry, Ultraviolet Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Ultraviolet Spectrophotometry

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