Abstract:The amount and change of Fe(II) is tightly related to the oxidation-reduction properties of soils and sediments. Inaccurate evaluation commonly occurs in spectrometry because of co-existed Fe(III). In the present work, the reliable spectrometric determination of Fe(II) was investigated by using the alternative chromogenic reagent of 2,2’-dipyridine and ferrozine. The results indicated that co-existed Fe(III) resulted in the overestimation of Fe(II) due to the formation of Fe(III) complexes with chromogenic reagent, and the overestimation extent depended on Fe(III) concentration and the types of chromogenic reagent. When 2,2’-dipyridine was chosen, Fe(II) could be overestimated by 0.012 mg/L per mg/L Fe(III). If ferrozine employed, the overestimation magnitude of Fe(II) ranged from 0.010 to 0.032 mg/L per mg/L Fe(III), which depended on Fe(III) concentration. Fluoride ion could efficiently inhibit the formation of Fe(III) complexes with chromogenic reagents. While Fe(III) was masked completely, the amount of added fluoride was estimated to be at least 4 times higher than Fe(III). With the modified method, Fe(II) in extractants of soils and sediments could be determined with a satisfactory result.