Rapid Determination of Chromium in Chromite Samples by Titrimetry with Ammonium Ferrous Sulfate

A method for the rapid determination of chromium in chromite samples by titrimetry with ammonium ferrous sulfate is reported in this paper. The factors influencing the determination of chromium were studied. Mixed flux of Na2O2-NaOH was used for sample decomposition. It has a better oxidation effect on chromium with 200 g/L ammonium persulphate in 0.5 mol/L sulfuric acid oxidation system and 5 mL of 20 g/L AgNO3 provided a better catalytic effect. 50 g/L NaCl could be used to eliminate the interference. The method has been applied to the determination of chromium in practical samples and the results are in agreementwith recommended values with precision of 0.18%～0.23%RSD(n=5). The method provides the advantages of simpility, high efficiency and reliability.