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OCR for page 68
68 NAS/CWTC 037-82 Name: SODIUM ZINC POTASSIUM POLYPHOSPHATE, GLASSY CAS No.: 65997-17-3 Chemical Formula: (MPO3)n Description: M2O P2O5 = 53-55% Where M = Na K- - = 1/2 an = 5 White to colorless glassy plates, granules or powder. Use e Used as corrosion inhibitor. Puritv Requirements: Analyses of available grades of glassy sodium zinc potas- sium polyphosphate show the presence of cadmium and lead, but at levels far below that which would necessitate RMIC values based on a maximum dosage of 13.7 to 14.1 mg/liter, depending on the P2O5 content of the specific product used. If analyses are desired, the following protocol is recomended. Bulk Sample Collection: Sample in accordance with Standard for Sodium Tripoly- phosphate, AWWA B503-78, American Water Works Association, Denver, Colorado (1978). Analytical Sample Preparation: Weigh out 2.5 g of sodium zinc potassium polyphosphate. In a 150-m1 acid-washed beaker, dissolve the sample in

OCR for page 68
69 100 ml of deionized distilled water. Under a hood, acid- ify the solution with concentrated HNO3 to a pH of less than 2. Gently heat the solution to reduce the volume below 100 ml, making certain that it does not boil. Quan- titatively transfer to a 100-m' acid-washed volumetric flask and make to volume with deionized distilled water. Process a reagent blank by the same procedure. Sample Analyses: The analyses are to be performed on the sodium zinc potas- sium polyphosphate solution in accordance with: Standard Methods for the Examination of Water and Waste- water, 15th Edition, American Public Health Association, Washington, D.C. (1981). Cadmium Lead Section 304 Section 304