The standard applies to all types of water. Notes 1. Phenols other than hydroxybenzene form compounds with deviating color and/or color intensity with the reagent. The measured levels may therefore deviate from the actual levels. 2. Dis urbances caused by colored compounds, by sulfur compounds such as sulfite and sulfide, and by compounds that form precipitates in an alkaline environment are eliminated (see 7).
NEN 3235 9.1-1978 history
1978NEN 3235 9.1-1978 Test methods for waste water. Photometric determination of the content of phenols voiatile with water vapour