1 Subject Content and Application Scope
This standard specifies ammonium molybdate spectrophotometric method of determining total phosphorus with potassium persulfate (or nitric acid-perchloric acid) as oxidizerand unfiltered water sample being digested.
Total phosphorus includes dissolved, granular, organic and inorganic phosphorus.
This standard is applicable to surface water, wastewater and industrial waste water.
With 25mL specimen taken, the minimum detectable concentration in this standard is 0.01mg/L, and the upper determination limit is 0.6mg/L.
Under acidic condition, the interference determination of arsenic, chromium and sulfur is carried out.
2 Principle
Under neutrality condition, potassium persulfate (or nitric acid-perchloric acid) is used to digest the sample, and oxidize all the phosphorus contained into orthophosphate. In acid medium, after orthophosphate reacts with ammonium molybdate to generate phosphorus-molybdenum heteropoly acid in the presence of antimonic salt, it’s reduced immediately by ascorbic acid to generate a blue complex.
1 Subject Content and Application Scope
2 Principle
3 Reagent
4 Instruments
5 Sampling and Sample
6 Analysis Procedures
7 Representation of Result
8 Precision and Accuracy
Additional Explanation
