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OCR for page 66
66 Name: SODIUM ZINC POLYPHOSPHATE, GLASSY CAS No.: 65997-17-3 NAS/CWTC 036-82 Formula Weight: Unknown Chemical Formula: (MPO3)n M2O Where M = Na and/or 1/2 Zn n = 5 P2O5 = 55-61% Description: White to colorless glassy plates Use: Corrosion inhibitor. Purity Requirements: , granules or powder. Analyses of available grades of glassy sodium zinc poly- phosphate show the presence of cadmium and lead, but at levels far below that which would necessitate RMIC values based on a maximum dosage of 12.3 to 13.6 mg/liter, de- pending on the P2O5 content of the specific product used. If analyses are desired, the following protocol is recommended. Bulk Sample Collection: Sample in accordance with Standard for Sodium Tri- polyphosphate, AWWA B503-78, American Water Works AS SOC iation, Denver, Colorado (1978).

OCR for page 66
67 Analytical Sample Preparation: Weigh out 2.5 g of sodium zinc 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 HNC3 to a pH of less than 2. Gently heat the solution to reduce the volume below loo 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. Pro- cess a reagent blank by the same procedure. Sample Analyses: The analyses are to be performed on the sodium zinc poly- phosphate 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