ISO 2999:1974
Withdrawn
A Withdrawn Standard is one, which is removed from sale, and its unique number can no longer be used. The Standard can be withdrawn and not replaced, or it can be withdrawn and replaced by a Standard with a different number.
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04-23-2019
English, French
12-01-1974
Applicable to products containing at least 90 % (m/m) of tetrasodium pyrophosphate and in the absence of more condensed forms of phosphates. The reaction based on conversion of tetrasodium pyrophosphate to disodium dihydrogenpyrophosphate by addition of hydrochloric acid. Introduction of zinc sulfate in solution for precipitation of zinc pyrophosphate and formation of sulphuric acid. Potentiometric titration of the sulphuric acid formed with standard volumetric sodium hydroxide solution. Has also been approved by the IUPAC.
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