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OCR for page 51
51 Name: SODIUM POLYPHOSPHATE, GLASSY CAS No.: 10124-56-8 Chemical Formula: Description: (NaPO3)n Na2O Na2O/P2O5 = 1.1 to 1.3 P2O5 = 63-68% NAS/CWTC 024-82 Typically, n = 14 Colorless, odorless, glassy solid, plates, granules, or powder. Slight salty taste. Hygroscopic and extremely soluble in water. Use: Used as metal corrosion inhibitor and sequestrant to avoid iron, copper and manganese discoloration. Threshold scale inhibitor and water softener. Purit Reauirements Y ~ . Analyses of available grades of glassy sodium polyphos- phate show the presence of cadmium and lead but at levels far below that which would necessitate RMIC values based on a maximum dosage of 10.7 mg/liter. If analyses are desired, the following protocol is recommended. Bulk Sample Collection: Sample in accordance with Standard for Sodium Tripolyphos- phate, AWWA B503-78, American Water Works Association, Denver, Colorado (1978).

OCR for page 51
52 Analytical Sample Preparation . Weigh out 2.5 g of sodium polyphosphate. In a 150-ml acid-washed beaker dissolve the sample in 100 ml of deionized distilled water. Under a hood, acidify 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. Quantita- tively transfer to a 100-ml 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 polyphos- phate 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