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Determination of Aflatoxins and Ochratoxin A in Traditional Turkish Concentrated Fruit Juice Products by Multi-Immunoaffinity Column Cleanup and LC Fluorescence Detection: Single-Laboratory Validation

Tugrul Kaymak, Levent Türker, Hüseyin Tulay, Joerg Stroka

J AOAC Int. 2018 Nov 1;101(6):1839-1849.

PMID: 29703271

Abstract:

Background: Pekmez and pestil are traditional Turkish foods made from concentrated grape juice, which can be contaminated with mycotoxins such as aflatoxins and ochratoxin A (OTA). Objective: To carry out a single-laboratory validation of a method to simultaneously determine aflatoxins B1, B₂, G1, and G₂ and ochratoxin A in pekmez and pestil. Methods: The homogenized sample is extracted with methanol-water (80 + 20) using a high-speed blender. The (sample) extract is filtered, diluted with phosphate-buffered saline solution, and applied to a multi-immunoaffinity column (AFLAOCHRA PREP®). Aflatoxins and ochratoxin A are removed with (neat) methanol and then directly analyzed by reversed-phase LC with fluorescence detection using post-column bromination (Kobra cell®). Results: Test portions of blank pekmez and pestil were spiked with a mixture of aflatoxins and ochratoxin A to give levels ranging from 2.6 to 10.4 μg/kg and 1.0-4.0 μg/kg, respectively. Recoveries for total aflatoxins and ochratoxin A ranged from 84 to 106% and 80-97%, respectively, for spiked samples. Based on results for spiked pekmez and pestil (30 replicates each at three levels), the repeatability RSD ranged from 1.6 to 12% and 2.7-11% for total aflatoxins and ochratoxin A, respectively. Conclusions: The method performance in terms of recovery, repeatability, and detection limits has been demonstrated to be suitable for use as an Official Method. Highlights: First immunoaffinity column method validated for simultaneous analysis of aflatoxins and ochratoxin A in pekmez and pestil. Suitability for use for official purposes in Turkey, demonstrated by single-laboratory validation. Co-occurrence of aflatoxins and OTA in mulberry and carob pekmez reported for the first time.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP911392422 Ochratoxin A-13C20 solution Ochratoxin A-13C20 solution 911392-42-2 Price
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