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Submitted to: Journal of Association of Official Analytical Chemists International
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/3/2008 Publication Date: 9/1/2008 Citation: Maragos, C.M. 2008. Extraction of Aflatoxin B1 and G1 from Maize using Aqueous Sodium Dodecylsulfate (SDS). Journal of Association of Official Analytical Chemists International. 91(4):762-767. Interpretive Summary: Aflatoxins are potent carcinogens produced by certain Aspergillus fungi, and are routinely found in commodities and foods worldwide. Because of this the accurate measurement of these toxins is important. For analysis the aflatoxins have traditionally been extracted from grains using solvents. In the early days of aflatoxin analysis this was done using chlorinated solvents, but handling of chlorinated solvents presents safety hazards and most current analytical methods for aflatoxins use non-chlorinated solvents such as methanol or acetonitrile. This manuscript describes the development of a solvent-free aqueous solution for extraction of aflatoxins from corn. The extraction is based upon the detergent sodium dodecyl sulfate (SDS), which is widely available and inexpensive. Extraction with the aqueous SDS was slightly less efficient than with a commonly used methanol-water extraction, yet recoveries of aflatoxins B1 and G1 from corn were very good. This manuscript provides the first evidence that solvent-free extraction of aflatoxins from corn may be feasible, reducing the need for expensive solvents, improving the safety of the extraction, and reducing solvent disposal costs. Technical Abstract: Aflatoxins are potent carcinogens that are produced by certain Aspergillus fungi. The aflatoxins were first discovered in the 1960s and since that time have been found to be distributed worldwide in a variety of commodities, foods, and feeds. Many of the early techniques for detecting aflatoxins involved extraction with halogenated solvents. With the increased availability and use of reverse-phase solid phase extraction cartridges and the availability of immunoaffinity columns, aqueous mixtures of non-halogenated solvents have been frequently used. To further reduce the need for solvents we examined the effects of eliminating solvents during the extraction of maize using aqueous mixtures of the detergent sodium dodecyl sulfate (SDS). Following extraction and filtration, aflatoxins B1 and G1 (AFB1, AFG1) were isolated using commercially available immunoaffinity columns. The isolated AFB1 and AFG1 were derivatized with trifluoroacetic acid before separation by liquid chromatography and detection by fluorescence. In spiked maize the limits of detection were 0.5 ng/g and 1 ng/g for AFB1 and AFG1 respectively. Recoveries of AFB1 spiked into maize between 1 and 20 ng/g, averaged 87.5% (range 76.3% to 99.0%), with an average repeatability standard deviation (RSDr) of 4.0%. Recoveries of AFG1 spiked into maize between 2 and 20 ng/g averaged 80.4% (range 70.3% to 85.8%), with an average RSDr of 3.5%. This is the first reported demonstration of an effective solvent-free extraction of aflatoxins from maize at ambient pressure, and may serve to help reduce solvent consumption during aflatoxin analysis. |
