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Degree Name

Doctor of Philosophy




Air samples are collected for analysis from the Ames Solid Waste Recovery System. The high level of airborne fungi within the processing area is of concern due to the possible presence of toxic mycotoxins, and carcinogenic fungal metabolites. An analytical method has been developed to determine the concentration of aflatoxins B1, B2, G1, and G2 in the air of the plant which produces Refuse Derived Fuel (RDF);After extraction with methanol, some components in the matrix are precipitated by dissolving the sample in 30% acetonitrile/chloroform. An aliquot of this solution is injected onto a Styragel column where the sample components undergo simultaneous size exclusion and reverse phase partitioning. Additional studies have provided a more thorough understanding of solvent related non-exclusion effects on size exclusion gels. The Styragel column appears to have a useable lifetime of more than six months. After elution from Styragel, the sample is diverted to a second column containing Florisil which has been modified with oxalic acid and deactivated with water;Aflatoxins are eluted with 5% water/acetone. After removal of this solvent, the sample is dissolved in 150 (mu)L of a spotting solvent and the entire sample applied to a thin layer chromatography (TLC) plate using a unique sample applicator developed here. The aflatoxins on the TLC plate are analyzed by laser fluorescence;A detection limit of 10 pg is possible for aflatoxin standards using a nitrogen laser as the excitation source. Sample concentrations are determined by comparing with an internal standard, a specially synthesized aflatoxin derivative. In two separate RDF samples, aflatoxin B1 was found at levels of 6.5 and 17.0 ppb. The analytical method has also proven useful in the analysis of contaminated corn and peanut meal samples;In a separate study, the spore pigment in Aspergillus flavus wasisolated. The mass spectrum indicates a molecular weight in excessof 700. Only aliphatic hydrocarbons have been identified in the massspectrum of products from a permanganate oxidation. The isolatedpigment is obviously a mixture and no further work was done to;elucidate structures;('1)This research was supported by U.S. Department of Energy, Contract No. W-7405-Eng-82.



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Merlin K. L. Bicking



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164 pages