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

Susan J. MacDonald*, Sharron Anderson, Paul Brereton, Roger Wood

*Corresponding author for this work

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

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 1.1M 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.

Original languageEnglish
Pages (from-to)1164-1171
Number of pages8
JournalJournal of AOAC International
Volume86
Issue number6
Publication statusPublished - 01 Nov 2003
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry
  • Food Science
  • Environmental Chemistry
  • Agronomy and Crop Science
  • Pharmacology

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