Determination of total and organic phosphorus by alkaline persulphate oxidation

14 Determination of total and organic phosphorus by alkaline persulphate oxidation 

It was observed that organically bound phosphorus is completely decomposed to phosphate when oxidized with persulphate in an alkaline medium. Furthermore, more than 60 % of condensed phosphates are hydrolyzed. As concentrations of polyphosphates are negligible in most natural waters, a simultaneous oxidation procedure for organic phosphorus and nitrogen compounds has been developed by Korolejf (1977). Valderrama (1981) compared the procedure with former methods using separate determinations. In the simultaneous oxidation, the pH of the reaction starts at ca. 9.7 and ends at 4-5. These conditions are obtained by a boric acid-NaOH system. In seawater samples no precipitation is formed when the oxidation mixture is added. At elevated temperatures a precipitation is formed, which, however, dissolves as oxidation proceeds. 

precision and interferences are identical to those outlined in Section 10.2.13. 

One of the two oxidizing reagents below is required in addition to the reagents listed for phosphate (see Section 10.2.5.4). 

Oxidizing reagent Dissolve 50 g of potassium peroxodisulphate and 30 g of boric acid in IL of 0.375 mol/L (15.00 g/L) NaOH. Store this solution at room temperature in a tightly closed polyethylene bottle wrapp ed with aluminium foil. The mixture is stable for several 

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See also in sourсe #XX -- [ ]

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