Metabolism Studies of Phenylsulfonamides Relevant for Water Works

Abstract

Polar organic contaminants in surface water for drinking water purposes are relevant if they are poorly degradable, and analyses of such compounds are challenging because they are extremely water soluble. The problem is enhanced with more polar and unknown metabolites such as Sarkosin- N -(phenylsulfonyl) (SPS) which was detected in the Rhine river constantly in concentrations between 0.5 and 2 μg/L. The ubiquitous presence of SPS in the water was initially hypothesized to be due to the microbial degradation in sewage plants of 6-[methyl(phenylsulfonyl)amino]hexanoic acid (HPS) which is extensively used in Germany as a corrosion inhibiting agent. Soil suspension as well as closed-bottle degradation experiments with sewage water confirmed this hypothesis. Immobilized cell systems simulated the behavior in underground passage. HPS was totally degraded within hours, while SPS and other metabolites such as 4-[methyl(phenylsulfonyl)amino]butanoic acid (BPS) and methyl(phenylsulfonyl)amide (MPS) were identified. These studies revealed that phenylsulfonamides should be included in the group of drinking water relevant compounds because of their positive identification in drinking water itself. Even if the toxic effects of the investigated phenylsulfonamides have not yet been substantiated possibly also due to their inadequate biodegradability, their presence in the environment is a concern in general and therefore should be minimized.