ÖNORM EN 1484

This European Standard gives guidance for the deterrnination of organic carbon in drinking water, ground water, surface water, sea water and waste water. It deals with definitions, interferences, reagents, and the sample pretreatment of water sampies with a content of organic carbon ranging from 0,3 rngli to 1000 mgll while the lower value is only appiicable in special cases, for example drinking water, measured with instruments capable of rneasuring these low levels. Higher concentrations rnay be determined after appropriate diiution. This European Standard does not deal with the instrument-dependent aspects. In addition to organic carbon the water sample may contain carbon dioxide or ions of carbonic acid. Prior to the TOC determination, it is essential that this inorganic carbon is removed by purging the acidified sarnple with a gas which is free from CO, and organic compounds. Alternatively, both total carbon (TC) and total inorganic carbon (TIC) rnay be determined and the organic carbon content (TOC) may be calcuiated by subtracting the total inorganic carbon from the TC. This rnethod is particularly suitable for samples in which the total inorganic carbon is iess than the TOC. Purgeable organic substances, such as benzene, toluene, cyclohexane, and chloroform may partly escape upon stripping. In presence of these substances the TOC contrentration is determined separately, or the differential method (TC - TIC = TOC) may be applied, By using the differential rnethod, the value of the TOC should be higher than the TIC, or at least of similar size. Cyanide, cyanate, and particlec of elemental carbon (soot) when present in the sarnple, will be determined together with the organic carbon. NOTE: In presence of humic material low values may occur when UV-radiation is used.