Colorimetric Determination of Oxidizable Carbon in Acid Soil Solutions

Abstract A simple and sensitive method is described that determines, colorimetrically, oxidizable organic matter in solutions from acid soils. It relies on measuring the loss of color by a Mn(III)‐pyrophosphate complex as Mn(III) becomes reduced by organic C in the presence of concentrated H 2 SO 4 . The method is applicable to 1‐mL samples containing 0.08 to 4.0 µmol of organic C and is practically free of interferences in aerobic solutions.