Chromatographic investigations of the behaviour of dichlobenil and 2,4,5-T in water during slow sand filtration [Herbicides]

In this study the behaviour of the herbicides dichlobenil and 2,4,5-T during slow sand filtration of surface water was investigated. Slow sand filtration is applied to artificial groundwater recharging of Ruhrwater. The herbicides were added into the Ruhrwater supply of a pilot plant. The quantitative determination of dichlobenil, 2,4,5-T and their metabolites was performed by high pressure liquid chromatography. Sample preparation and analysis were simplified either by direct injection of the filtered water sample into a liquid chromatograph or by using a column switching system consisting of a short precolumn as enrichment column and an analytical column-this was used when working in the ppb range. With dichlobenil a partial elimination by adsorption and degradation was observed. The elimination rate of 2,4,5-T was very low, only app. 10% of the added amount; no degradation product was observed.