Determination of Aflatoxins B₁, B₂, G₁, and G₂ and Ochratoxin A in Ginseng and Ginger by Multitoxin Immunoaffinity Column Cleanup and Liquid Chromatographic Quantitation: Collaborative Study

Author： Trucksess Mary W Weaver Carol M Oles Carolyn J Fry Frederick S Noonan Gregory O Betz Joseph M Rader Jeanne I

Publisher： AOAC International

ISSN： 1944-7922

Source： Journal of AOAC International, Vol.91, Iss.3, 2008-05, pp. : 511-523

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Abstract

The accuracy, repeatability, and reproducibility characteristics of a method using multitoxin immunoaffinity column cleanup with liquid chromatography (LC) for determination of aflatoxins (AF; sum of aflatoxins B₁, B₂, G₁, and G₂) and ochratoxin A (OTA) in powdered ginseng and ginger have been established in a collaborative study involving 13 laboratories from 7 countries. Blind duplicate samples of blank, spiked (AF and OTA added) at levels ranging from 0.25 to 16.0 g/kg for AF and 0.25 to 8.0 g/kg for OTA were analyzed. A naturally contaminated powdered ginger sample was also included. Test samples were extracted with methanol and 0.5 aqueous sodium hydrogen carbonate solution (700 + 300, v/v). The extract was centrifuged, diluted with phosphate buffer (PB), filtered, and applied to an immunoaffinity column containing antibodies specific for AF and OTA. After washing the column withwater, the toxins were eluted from the column with methanol, and quantified by high-performance LC with fluorescence detection. Average recoveries of AF from ginseng and ginger ranged from 70 to 87 (at spiking levels ranging from 2 to 16 g/kg), and of OTA, from 86 to 113 (at spiking levels ranging from 1 to 8 g/kg). Relative standard deviations for within-laboratory repeatability (RSD_r) ranged from 2.6 to 8.3 for AF, and from 2.5 to 10.7 for OTA. Relative standard deviations for between-laboratory reproducibility (RSD_R) ranged from 5.7 to 28.6 for AF, and from 5.5 to 10.7 for OTA. HorRat values were 2 for the multi-analytes in the 2 matrixes.