S. Krause, H. Schöler, T. Heberer
Mar 1, 2000
Citations
0
Influential Citations
2
Citations
Journal
Environmental Science & Technology
Abstract
SIR: Knepper et al. present an interesting study on the metabolism of phenylsulfonamide, explaining the formation of the ubiquitous sarcosine-N-(phenylsulfonyl) (SPS) by degradation of 6-[methyl(phenylsulfonyl)amino]hexanoic acid (HPS) via a 2-fold â-oxidation (1). Knepper et al. used the frequently applied diazomethane for derivatization, which creates a problem for the quantification of sarcosine-N(phenylsulfonyl), as shown by Krause et al. in a paper entitled “N-(phenylsulfonyl)glycinesa new contaminant in sewageand surface water” published in Chemosphere in 1998 (2). When SPS was detected by Heberer et al. in sewage farm waters and in sewage plants near Berlin (3-5) as well as in surface water samples at a number of locations in Germany and Italy (6, 7) and by Knepper et al. in several rivers in Germany (8, 9), Krause et al. addressed the question of whether further phenylsulfonylamides exist in the environment. River samples (e.g. river Rhine, river Neckar; Germany) and samples from municipal sewage treatment plants were investigated for glycine-N-(phenylsulfonyl) (GPS), alanineN-(phenylsulfonyl), and sarcosine-N-(phenylsulfonyl) as well as for their corresponding p-toluene analogues (10). To detect glycine-N-(phenylsulfonyl) and sarcosine-N-(phenylsulfonyl) simultaneously, Krause et al. applied diazoethane for derivatization. The distinguishing feature between GPS and SPS is the methyl group of SPS at the nitrogen. On derivatization with diazomethane, the secondary aminogroup of glycine-N-(phenylsulfonyl) is methylated, and thus GPS cannot be distinguished from sarcosine-N-(phenylsulfonyl) (see Figure 1). By using diazoethane GPS can be distinguished from SPS by retention time and mass spectrum, also after ethylation of the secondary amino group. GPS was identified not only by the mass spectrum but also by its retention time comparing to the corresponding standard. So there is no doubt about the identification of GPS. As a result of the investigations carried out by Krause et al., glycine-N-(phenylsulfonyl) was identified as an hitherto unknown polar contaminant (2, 10). In surface waters, the concentrations of GPS ranged between 50 and 850 ng/L. In municipal sewage treatment plants the concentrations varied: GPS was only found in one influent waste water sample with a concentration of 1200 ng/L; in the biological clarification step and in the effluent its concentration ranged from 80 to 300 ng/L. The measured GPS concentrations were always lower than those of the sarcosine derivative, nevertheless the GPS concentrations could not be ignored. Thus by using diazomethane for derivatization Knepper et al. could not distinguish between SPS and GPS. Their measured SPS concentration is the sum of SPS and GPS!