Digester for Total Phosphorus


This module is an accessory for the 3S phosphorus analyzer. It allows the analysis of all forms of phosphorus through a complete digestion of the sample. The digestion happens in the instrument reactor where the sample is mixed with acid/persulfate and processed using heat and UV radiation. After the treatment, the sample can be analyzed using the 3S colorimetric analyzer for the phosphate ion. The module can also perform dilution of the sample thus increasing the maximum allowed range of the 3S phosphate analyzer.

Digester for Total Phosphorus

Product code

  • A46DIGUN00 - Digester for Total Phosphorus

Working principle

Phosphorus occurs in several forms: ortho, poly and organically bound. Further classification can be made on whether the phosphorus is dissolved (passing through a 0.45 micron filter). In TP oxidation / digestion, polyphosphates and organic phosphorus are converted into orthophosphate. Organic phosphorus is converted to orthophosphate by UV catalyzed persulfate digestion; polyphosphates are converted to orthophosphate by sulphuric acid digestion. All forms of phosphorus are converted to its ortho form in the TP procedure, in the presence of persulfate and an acid background. The Total Phosphorus concentration can be measured using two different methods depending on the range requested. Both methods use advanced photochemical oxidation, sulphuric acid, heat, UV irradiation and a chemical oxidizer (sodium persulfate). After the complete oxidation of the phosphorus in the sample to PO43-, then a colorimetric reaction is performed and the intensity of the colour developed is proportional to the phosphate concentration present in the sample.

Related products

3S Phosphate Analyzer