Guidelines for improving organic carbon recovery by the wet oxidation method

The study of soil degradation processes as well as the monitoring of environmental quality often yields large sample batches in which organic carbon is the key property to be determined. A description is given for a rapid method to analyse organic carbon by wet oxidation; the reaction is carried out with 3 ml K2Cr2O7 and 6 ml H2SO4 in small vials, and Cr3+ resulting from organic C oxidation is determined by spectrophotometry. No special equipment is needed and handling is reduced to a minimum, enabling over 100 samples per day to be analysed. There is one important detail in the operation protocol: the vials are placed inside an insulator block during oxidation. Heat insulation retards the cooling of vials, which results in a high organic C recovery (over 0.90). The improved method is feasible, simple, and easy to perform. Reproducibility was lower than 10% and recoveries from certified reference materials were about 90%. The simplified method is recommended for widespread organic C content sampling.