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Submitted to: Journal of Association of Official Analytical Chemists International
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/21/2001 Publication Date: 1/15/2002 Citation: Sobolev, V.S., Dorner, J.W. 2002. Cleanup procedure for determination of aflatoxins in major agricultural commodities by liquid chromatography. Journal of Association of Official Analytical Chemists International. 85(3):642-645. Interpretive Summary: Aflatoxins are a group of toxic, carcinogenic compounds produced by some common soil fungi that often contaminate a wide variety of agricultural products. Aflatoxins are monitored by governmental and commercial structures in many countries of the world with the help of various chemical, antibody-based, and immunoassay methods that are selective and sensitive, but expensive. The purpose of this work was to develop a simple, fast, reliable, inexpensive chemical cleanup procedure for analysis of aflatoxins in major agricultural products using liquid chromatography (LC), a common laboratory technique. Such a method has been developed. Aflatoxins were extracted from a ground sample with methanol-water, and after a single cleanup step on a minicolumn packed with basic aluminum oxide, aflatoxins were quantified by LC. Recoveries of aflatoxins B1, B2, G1, and G2 from peanuts spiked at 5.0, 2.5, 7.5, 2.5 ppb were 87.2, 82.0, 80.0, and 80.4%, respectively. The precision of the method was very good as evidenced by coefficients of variation averaging 2.0% for all commodities spiked in the range of 2.5-150.0 ppb. The quantitation limit for aflatoxin B1 was 1 ppb. In addition to peanuts, the method was effective for the analysis of corn, cottonseed, almonds, Brazil nuts, pistachios, and walnuts. The minimal cost of the minicolumn allows for substantial savings compared with available commercial aflatoxin cleanup devices. Technical Abstract: A simple, fast, reliable, and cheap chemical cleanup method for quantitation of aflatoxins in major important agricultural commodities using LC has been developed. Aflatoxins were extracted from a ground sample with methanol-water (80+20, v/v), and after a single cleanup step on a minicolumn packed with basic aluminum oxide, aflatoxins were quantified by LC equipped with a C18 column, a photochemical reactor, and a fluorescence detector. Water - methanol - 1-butanol (1400+720+25, v/v/v) served as the mobile phase. Recoveries of aflatoxins B1, B2, G1, and G2 from peanuts spiked at 5.0, 2.5, 7.5, 2.5 mg/kg were 87.2±2.3, 82.0±0.8, 80.0±1.8, and 80.4±2.8%, respectively. Similar recoveries, precision, and accuracy were achieved for corn, cottonseed, almonds, Brazil nuts, pistachios, and walnuts. The quantitation limit for aflatoxin B1 was 1 mg/kg. The minimal cost of the minicolumn allows for substantial savings compared with available commercial aflatoxin cleanup devices. |
