Green quantification of amino(poly)phosphonates using ion chromatography coupled to integrated pulsed amperometric detection.

Abstract

Aminopolyphosphonates (APPs) are widely used as chelating agents, and their increasing release into the environment has raised concerns due to their transformation into aminomethylphosphonic acid (AMPA) and glyphosate, compounds of controversial environmental impact. This transformation highlights the urgent need for detailed studies under controlled conditions. Despite the availability of various methods for quantifying individual aminopolyphosphonates and aminomonophosphonates, a green, low-cost approach for the simultaneous quantification of APPs and their transformation products in laboratory experiments has been lacking. In this study, we present a novel analytical method utilizing ion chromatography (IC) coupled to integrated pulsed amperometric detection (IPAD) to simultaneously quantify the six aminophosphonates: AMPA, glyphosate, iminodi(methylene phosphonate) (IDMP), aminotrismethylene(phosphonates) (ATMP), ethylenediamine tetra(methylene phosphonate) (EDTMP), and diethylenetriamine penta(methylene phosphonate) (DTPMP). This method achieves separation within a 35-min run time and method detection limits (MDLs) ranging from 0.014 μM for AMPA to 0.14 μM for DTPMP. The method's applicability was successfully shown by monitoring DTPMP, IDMP, and AMPA during DTPMP transformation on manganese dioxide. A key advantage of this method is its environmental friendliness compared to existing aminophosphonate quantification techniques. Next to the simultaneous analysis, it avoids the use of derivatization agents and organic solvents and employs an energy-efficient detector. While the method's limitations lie in the detector's inherent non-specific nature, it offers a low-cost and sustainable alternative to existing methods.