Abstract New research and practice on page 71 of textbook Chemistry Volume 1(Compulsory) (People’s Education Press, 1st edition, 2019):Testing iron in food provided the experimental scheme for reference, the spinach juice was tested by adding dilute nitric acid and potassium thiocyanate solution. Because nitric acid and potassium thiocyanate may also produce red, this paper proved that the method had interference through the blank experiment, and designed two representative experimental schemes: blanching test and burning test. The experiment showed that: the effect of oxalic acid and chlorophyll in spinach was eliminated by burning, then added acid to dissolve, and then iron could be tested. If the oxidant was added, the phenomenon would be more obvious, 0.2 mol/L dilute sulfuric acid +5% H2O2+3 mol/L KSCN was selected for the experiment, and the effect was more obvious.
