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Cereal Chem 53:91 - 100.  |  VIEW ARTICLE
A New Method of Analysis of Protein Content in Grain by Proton Activation.

D. A. Dohan, K. G. Standing, and W. Bushuk. Copyright 1976 by the American Association of Cereal Chemists, Inc. 

This new technique measures the total nitrogen in a sample like the classical Kjeldahl method, but uses a nuclear reaction instead of a chemical reaction. A beam of 16 MeV protons strikes a sample of grain and produces radio active 140 nuclei through the reaction 14N+p-140+n. The 140 decay (half-life 71 sec) is detected off-line by its characteristic 2.31 MeV gamma-ray. The ratio of the number of gamma-rays counted to the total number of protons striking the sample determines the abundance of nitrogen. The gamma-rays provide a unique identification of this nuclear reaction and thus an unambiguous measure of the nitrogen content of the sample. The method is applicable to either whole or ground grain. Weighing the sample is unnecessary since its effective thickness is determined by the proton range (approximately equal to 0.23 g/cm2). Samples of barley, common wheat, durum wheat, oats, rapeseed, rye, triticale, and high-protein flour have been tested. Accuracy is comparable to the accuracy of the Kjeldahl method. When developed, the technique should be capable of analyzing approximately 10 samples per min, with resulting advantages in cost.

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