Process for determining the amount of organic phosphonate present in an aqueous solution

Abstract

The instant invention is directed to a process for determining the amount of organic phosphonate present in an aqueous solution, comprising the steps of: (a) adding 1000 to 20,000 ppm of a strong oxidizing agent and 8 ppb to 5000 ppm silver ion to the aqueous solution; (b) allowing the organic phosphonate present in said solution to react to form orthophosphate; (c) precipitating any excess silver in said solution by the addition of 1000 to 50,000 ppm of a reducing agent or at least an equimolar amount of a halide, based on the silver ion added in Step (a), and removing any precipitate formed; (d) adding to said solution 5 to 30 percent, by volume, of an acid solution containing 500 to 2000 ppm of ions selected from the group consisting of molybdate ion and vanadate ion, and if a halide was used in Step (c), adding 1000 to 50,000 ppm of a reducing agent; (e) measuring the absorbance of said solution at 625 to 880 nanometers and determining the orthophosphate concentration from a calibration curve of orthophosphate concentration versus absorbance; and (f) subtracting any orthophosphate present in the original aqueous solution from the orthophosphate concentration determined in Step (e), to give the total organic phosphonate concentration.

Dependencies are inferred from the claim text.