Spectrophotometric analysis of water quality - Determination of total phosphorus

In neutral condition, potassium persulfate (or nitric acid perchloric acid) is used to digest the sample, and all the phosphorus contained is oxidized to orthophosphate In acid medium, orthophosphate reacts with ammonium molybdate to form phosphomolybdic heteropoly acid in the presence of antimony salt, which is immediately reduced by ascorbic acid to form a blue complex This standard specifies a method for the determination of total phosphorus by ammonium molybdate spectrophotometry with potassium persulfate (or nitric acid perchloric acid) as oxidant to digest unfiltered water sample Total phosphorus includes dissolved, granular, organic and inorganic phosphorus This standard is applicable to surface water, sewage and industrial waste water Take 25ml water sample, the minimum detection concentration of this standard is 0.01mg/l, and the upper limit is 0.6mg/l Under acid condition, arsenic, chromium and sulfur interfere with the determination.