Modified Method for Determination of Tannin, Lignin and Humic Substances

摘要

The equipment and reagents needed to conduct a procedure for determining tannin, lignin, and humic substances are discussed. It is found that tannins and lignins reduce tungstophosphoric and molybdophosphoric acids to produce a blue color suitable for the estimation of concentrations up to at least 9 mg/L at wavelength 600-700 nm for tannin acid or lignin. Soluble humic substances reduce the same tungstophosphoric and molybdophosphoric acids to produce a grayish color up to at least 20 mg/L at UV wavelength 265-400 nm.