Abstract Blank test proved that concentration greater than 1 mol/L HCl solution as extraction liquid of Fe3+, or concentrated hydrochloric acid solution as acidified solution, the Fe3+ in hydrochloric acid would bring interference to test Fe3+ in the test solution. When checking the iron element in food, if the iron was in the form of Fe2+, if adding hydrogen nitrate to oxidize Fe2+ to Fe3+, Fe3+ in hydrogen nitrate would bring interference to test Fe3+ in the test solution.
