Indophenol Blue Colorimetric Method to Determine Grain Protein Content of Cereal Plants

Here, we propose a method to convert the organic nitrogen in maize kernels into ammonia in solution and then chlorinate it to prepare monochloride salts, which can form an oxidatively coupled blue-green mixture with sodium salicylate and sodium dichloroisocyanurate. The concentration of ammonium ions in the blue-green mixture can then be determined in the solution, and finally the protein content in maize kernels can be calculated from the nitrogen content.