Determination of phosphonates in natural waters by ion-pair high-performance liquid chromatography.

The paper describes a new method for the determination of phosphonates by ion-pair high-performance liquid chromatography. The phosphonates are complexed with Fe(III) and separated on a reversed-phase polymer column. The eluent consists of a bicarbonate solution at pH 8.3, tetrabutylammoniumbromide as counter-ion and 14% acetonitrile. The complexes are detected at 260 nm. The four phosphonates HEDP (1-hydroxyethylene-1,1-diphosphonic acid). ATMP (aminotris [methylenephosphonic acid]), EDTMP [ethylenediaminetetra(methylenephosphonic acid)], and DTPMP [diethylenetriaminepenta (methylenephosphonic acid)] are well separated within 20 min. The limits of detection are 5.10(-8) M for ATMP and EDTMP, 1.10(-7) M for DTPMP and 5.10(-7) M for HEDP. The method is suitable for the determination of phosphonates in the influent and effluent of wastewater treatment plants. A preconcentration of 10 is easily achieved by adsorption of the phosphonates onto freshly precipitated calcium carbonate and subsequent dissolution of the solid-phase by HCl.