Nitric acid concentrated acid and nitric oxide for dilute acid. or Concentrated nitric acid oxidizes I, P, and S into HIO, HPO, and HSO, respectively. Nitric acid reacts with proteins to form yellow nitrated products. This reaction is known as the xanthoproteic reaction. This test is carried out by adding concentrated nitric acid to the substance being tested, and then heating the mixture. If proteins that contain amino acids with aromatic rings are present, the mixture turns yellow. Upon adding a base such as ammonia, the color turns orange. These color changes are caused by nitrated aromatic rings in the protein. Xanthoproteic
Fulvic acid only method that the California departments of agriculture will accept when registering a product. California does not recognize fulvic acid as separate substance from humic acid and requires that all label registrations list the content as humic acid only. Until 2017, Oregon also required using this method but has recently switched to the Lamar Method of fulvic acid quantification and now allows the label registration of fulvic acid as a substance apart from humic acid. The Verploegh and Brandvold method (V&B) quantifies both humic and fulvic acid and is a quick, cost effective, and easy test to perform. It does