Cereal Chem 51:788 - 797.  |  VIEW ARTICLE
Heavy Metals in Whole Kernel Dent Corn Determined by Atomic Absorption.

W. J. Garcia, C. W. Blessin, and G. E. Inglett. Copyright 1974 by the American Association of Cereal Chemists, Inc. 

Whole kernel corn was wet-ashed with nitric and perchloric acids, and the resultant salts were dissolved in dilute acid. Concentration levels in corn samples were determined for zinc, manganese, copper, lead, cadmium, and chromium by flame atomic absorption. Because this technique is not sensitive enough to measure the small quantities of mercury present, an oxidation procedure was developed that decomposed organic material in corn at a temperature of 70 C. The mercury was retained effectively in an aqua regia solution until the elemental mercury was de-emanated for measurement of the vapor by a nonflame atomic absorption technique. The aqua regia solution ensured that mercury was completely solubilized. In addition, mercury standards prepared in a 10% aqua regia medium have proved to be stable at low concentrations for extended periods. Mean concentration values for the seven metals studied in 11 different corn samples ranged from a high of 23 gamma per g. for zinc to a low of approximately 0.0024 gamma per g. for mercury.