Characterization of 14C residues in the grain of rice plants grown in soil treated with [phenyl-14C]-2-(diphenylmethoxy)acetic acid methyl ester
1991
Nadeau, R.G. | Howe, R.K. | Burnett, T.J. | Lange, B.D.
A study was conducted on the uptake of 14C residues in grain from field-grown rice plants treated shortly after planting with [phenyl-14C]-2-(diphenylmethoxy)acetic acid methyl ester ([14C]DME) and nonradioactive butachlor. Treatment rates of 0.061 and 0.16 kg/ha [14C]DME resulted in residues of 0.015 and 0.060 ppm in the polished rice. Extraction of powdered polished rice with an optimized solvent resulted in only 3.9% extraction of radioactivity. Treatment of the extracted rice with alpha-amylase gave a soluble fraction containing 80% of the radioactivity and a nonsolubilized material. The soluble fraction was treated with alpha-glucosidase to convert maltose to glucose, yielding a material called the starch hydrolysate. HPLC experiments on the starch hydrolysate and its product from acetylation indicated that [14C]glucose was the only detectable radioactive compound present, and 1H NMR analysis of the acetylation product showed that it consisted of a mixture of the alpha and beta isomers of D-glucose pentaacetate. The results indicated that most of the radioactivity in the polished rice was incorporated in natural constituents, mainly in glucose units of starch.
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