Product Notes
- 7918670 reads
Interferences
The temperature of the sample must be below 50°C.
Care must be taken to allow as little contact with air as possible. For example, do not filter the sample. Keep the buret tip below the surface of the sample.
Other oxidizable substances, such as organic compounds, ferrous iron and sulfide are positive interferences. Sulfide may be removed by adding 0.5 g of zinc acetate and analyzing the supernatant of the settled sample.
Nitrite gives a negative interference by oxidizing sulfite when the sample is acidified; this is corrected by either using a proprietary indicator which eliminates nitrite or by adding sulfamic acid.
Copper and possibly other heavy metals catalyze the oxidation of sulfite; EDTA is used to complex metals.
A blank must be run to correct for interferences present in the reagents
Interferences and precaution of test :::
The temperature of the sample must be below 50°C.
Care must be taken to allow as little contact with air as possible. For example, do not filter the sample. Keep the buret tip below the surface of the sample.
Other oxidizable substances, such as organic compounds, ferrous iron and sulfide are positive interferences. Sulfide may be removed by adding 0.5 g of zinc acetate and analyzing the supernatant of the settled sample.
Nitrite gives a negative interference by oxidizing sulfite when the sample is acidified; this is corrected by either using a proprietary indicator which eliminates nitrite or by adding sulfamic acid.
Copper and possibly other heavy metals catalyze the oxidation of sulfite. EDTA is used to complex metals.
A blank must be run to correct for interferences present in the reagents.
