Chemiluminescent determination of humic substances based on the oxidation by peroxymonosulfate

The intensity of emission radiation produced by humic (HA) and fulvic acids (FA) in the presence of SO52− in basic medium was used to determine HA and FA in the range of 0.5-20.0 mg l−1. The detection limit was 0.24 mg l−1. A comparative study was carried out using H2O2 in the presence of CH2O as oxidizing agent. Humic substances (HS) from several soil sources, different extraction and purifying procedures led to different calibration sensitivities and selectivity. Cations and anions such as Cu(II), Cr(III), Ca(II), Cl−, EDTA2−, NO3−, PO43− and CO32−, did not interfere with the determination of HA. Although it was not possible to confirm the accuracy of the chemiluminescent method, low concentrations of HS in natural waters can be detected.