1.1 This standard specifies the potassium periodate spectrophotometric method used for determination of manganese in water.
This standard is applicable to the determination of filterable manganese and total manganese in drinking water, surface water, groundwater and industrial wastewater.
1.2 Determination range
In case of using a cuvette with an optical path length of 50mm and a test portion with a volume of 25mL, the minimum detection concentration of the method is 0.02mg/L and the upper limit of determination is 3mg/L. For water samples high in manganese, the amount of test portion may be reduced appropriately or a cuvette with an optical path length of 10mm may be adopted, and the upper limit of determination may reach 9mg/L.
2 Definitions
2.1
filterable manganese
amount of manganese determined in the filtrate, i.e. soluble manganese, obtained by filtering and acidifying the filtrate with a 0.45μm filter on site immediately after the sample is collected
2.2
total manganese
amount of manganese determined after digestion, which is obtained by acidifying the sample immediately (without filtration) after it is collected
3 Theory
In a neutral potassium pyrophosphate medium, potassium periodate may oxidize low-priced manganese to purple-red heptavalent manganese in an instant at room temperature. Then determine the content of manganese at 525 nm with the spectrophotometric method.
