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OCR for page 72
72 Name: TETRASODIUM PYROPHOSPHATE CAS No: 7722-88-5 Chemical Formula: Na4P2O7 Formula Weight: 266 Description: White, odorless crystals or granules. Use: Used as corrosion inhibitor. Purity Requirements: NAS/CWTC 039/82 Na4P2O7 1OH2O 446 Analyses of available grades of tetrasodium pyrophosphate show the presence of cadmium and lead but at levels far below that which would necessitate RMIC values based on a maximum dosage of 14 mg/liter. Bulk Sample Collection: Sample in accordance with the Standard for Sodium Tripoly- phosphate, AWWA B503-78, American Water Works Association, Denver, Colorado (1978). 1 Analytical Sample Preparation: Weigh out 2.5 g of tetrasodium pyrophosphate. 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. Quanti-

OCR for page 72
73 tatively 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 tetrasodium pyrophosphate 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