Aminopolyphosphonates such as diethylenetriaminepenta(methylenephosphonic acid) (DTPMP) and ethylenediaminetetra(methylenephosphonic acid) (EDTMP) are versatile chemicals that are used in household and industrial applications as complexing agents, corrosion inhibitors and bleach stabilisers. In 2019, over 7,000 tonnes of aminopolyphosphonates were used in Germany in detergents and cleaning agents [1], as well as in the paper and textile industries, in water treatment and in cooling circuits. In sewage treatment plants, approximately 80–90% are retained through adsorption processes. [2] The remaining proportion reaches surface waters, where concentrations in the µg/L range have been detected in river water and in the mg/kg range in sediments. [3]

Due to their high stability and known transformation products such as phosphate and aminomethylphosphonic acid (AMPA), aminopolyphosphonates are increasingly becoming the focus of environmental analysis. The formation of transformation products from DTPMP and EDTMP has hardly been investigated to date, partly due to analytical challenges. A meta-analysis of international water data showed a clear wastewater origin of glyphosate and its degradation product AMPA and hypothesised that glyphosate, like AMPA, is not introduced through its use as a herbicide, but is formed from aminopolyphosphonates. [4] This would make aminopolyphosphonates a long-standing, previously unrecognised source of glyphosate in surface waters. 

My doctoral thesis therefore focuses on technical and environmentally relevant processes that may be relevant to this previously overlooked entry pathway. The transformation products of EDTMP and DTPMP are investigated in: oxidation in the presence of transition metals, photolysis, ozonation and degradation in sewage sludge (a paper has already been published on this subject: [5]). Both C-N and C-P bonds can be broken, and oxidation occurs at carbon and nitrogen atoms, resulting in a variety of structurally closely related and partially isomeric transformation products. The aim of my doctoral thesis is to identify transformation products and elucidate the various transformation and degradation pathways of DTPMP and EDTMP in order to understand, among other things, the formation of glyphosate and AMPA from aminopolyphosphonates.

For this non-target or suspect-target analysis, I use many different analytical methods such as capillary electrophoresis mass spectrometry, liquid chromatography mass spectrometry, 1H and 31P NMR spectroscopy, and, in collaboration with other working groups and institutions, other analytical methods, e.g. using ion chromatography. In addition, the synthesis of potential and suspected transformation products for the qualitative identification of sample components is also part of my area of responsibility, as internal standards are usually not commercially available.

Cooperation partners:

• Zweckverband Landeswasserversorgung, Operations and Research Laboratory

• University of Stuttgart, Institute for Sanitary Engineering, Water Quality and Waste Management

• Berliner Wasserbetriebe

Teaching:

• Advanced practical course in physical chemistry for Bachelor's degree in chemistry (AN3P)

• Physical chemistry internship for students of bioinformatics, computer science, physics

• Physical chemistry internship for students of pharmacy

References:

[1] Industrieverband Körperpflege- und Waschmittel e.V. (IKW), Sustainability Report 2021.

[2] Rott, E.; Happel, O.; Armbruster, D.; Minke, R. Behavior of PBTC, HEDP, and Aminophosphonates in the Process of Wastewater Treatment. Water 2020, 12, 53. doi.org/10.3390/w12010053.

[3] Eisemann, L. Phosphonates in detergents and cleaning agents and their fate in the environment – Federal Environment Agency, 2021, ISSN 1862-4804.

[4] Schwientek, M.; Rügner, H.; Haderlein, S.B.; Schulz, W.; Wimmer, B.; Engelbart, L.; Bieger, S.; Huhn, C., Glyphosate contamination in European rivers not from herbicide application?, Water Research 2024, 263, 122140. doi.org/10.1016/j.watres.2024.122140.

[5] Engelbart, L.; Bieger, S.; Thompson, K.; Fischer, L.; Bader, T.; Kramer, M.; Haderlein, S.B.; Röhnelt, A.M.; Martin, P.R.; Buchner, D.; Bloch, R.; Rügner, H.; Huhn, C., In-situ formation of glyphosate and AMPA in activated sludge from phosphonates used as antiscalants and bleach stabilisers in households and industry. Water Research, 2025, 280, 123464. doi.org/10.1016/j.watres.2025.123464.