Application of differential UV spectroscopy to the determination of lignin substances in polluted water

The absorption spectra of Bjorkman lignin, lignin sulfate, lignosulfonates, and humic substances in neutral and alkaline media are considered. It was found that the difference spectra of lignins (an alkaline solution with reference to a neutral solution) exhibited several intense bands, whereas humic substances exhibited equal shifts of the spectra over the entire spectral range. This distinctive property of the difference spectra of lignin substances, as compared to the spectra of humic substances, can be used for determining lignins in polluted water.