testingmethodsop

 PURPOSE: To describe the Laboratory standard operating procedure for measurement of Dissolved Oxygen of Water and Waste Water samples. SCOPE: Applicable to the Laboratory for analysis of Water and Waste Water samples, where measurement of Dissolved oxygen is required.   RESPONSIBILITY:  Lab chemist : Analysis of sample for measurement of Dissolved oxygen. Technical Manager : Review of activity  Quality Manager : Implementation and compliance of SOP. PROCEDURE:  Principle: Oxygen present in sample oxidize the divalent Mn to its high valency which precipitates as a brown hydrate oxide after addition of sodium hydroxide and KI. Upon acidification, manganese reverts to divalent state and liberates iodine from potassium iodideiodidel equivalent to DO content in the sample. The liberated iodine is titrated against 0.025N Na2S2O3 using starch as indicator. Instrument and Equipment: BOD bottles 300ml capacity, 25 ml Burette  Reagents:  Magnus sulfate: Dissolv...