ROBERT M FAUST
Vehicle Board in Pittsburgh, PA

4544639, Oct 1, 1985

Oct 21, 1983

6/544033

Robert J. Faust - Pittsburgh PA

Calgon Corporation - Pittsburgh PA

G01N 2175

436104

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.