Most of the NOM consist of humic acids. However, the aforementioned effects are often determined by other small fractions. Therefore, it is very important to obtain a further characterization of NOM.
Since 2006, Het Waterlaboratorium invested in an instrument for NOM, developed by DOC-Labor. The NOM is being separated by size chromatographically, and detected with an online DOC-measurement. This consist of a reactor in which a very thin film of eluent is formed, which then is irradiated with UV-light. The organic material present, is directly converted into carbon dioxide, which then is measured with an infrared detector. In one chromatogram, six various fractions can be distinguished from a concentration of 0,2 mg carbon/L.
This method is mainly used for investigation of new treatment steps, especially in pilot installations. Besides, this method is proven to be suitable for research into contamination of membranes.