BS 4427-11:1983

This Part of BS 4427 describes a method for the separation and the determination of the different phosphate forms in sodium tripolyphosphate (pentasodium triphosphate) and sodium pyrophosphate (tetrasodium diphosphate) for industrial use.

The procedure specified allows the selective determinations of orthophosphate (Na₂HPO₄), of pyrophosphate (Na₄P₂O₇) and of tripolyphosphate (Na₅P₃O₁₀), and also the evaluation of the total content of more condensed forms of phosphates in the absence of tetrametaphosphates and pentametaphosphates.

NOTE 1 In practice, tetrametaphosphates and pentametaphosphates are not usually present in commercial tripolyphosphates and pyrophosphates.

NOTE 2 Although the procedure can separate orthophosphate, its determination is not possible if the content is lower than 0.1 % (m/m); in this case its determination should be carried out by the method specified in BS 4427-8.

NOTE 3 The titles of the publications referred to in this Part of this British Standard are listed on the inside back cover.

Determination of ortho-, pyro- and tripolyphosphates, and higher condensed phosphate forms, in the absence of $7Itetra$7R- and $7Ipenta$7R-metaphosphates.