| 摘要 |
For a determination of nitrite in aqueous phosphating solutions which contain simple and/or complex fluorides, a bath sample of the phosphating solution is acidified with sulfuric acid, nitric acid and/or perchloric acid and in the presence of aluminum ions in a molar surplus of at least five times over the fluoride content of the phosphating solution is titrated by the cerium (IV) sulfate method with an oxidation-reduction electrode used for an electric indication. Preferably, the bath sample is acidified with sulfuric acid and the aluminum ions are added as aluminum sulfate-18-hydrate. The method for determination can be used to advantage for a control of metering means for controlling the supply of nitritecontaining make-up concentrate to phosphating solutions.
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