Sum of orthophosphate and hydrolyzable phosphorus compounds

2 Sum of orthophosphate and hydrolyzable phosphorus compounds General remarks 

Separate quantitative determination of orthophosphate, hydrolyzable phosphates and organic phosphorus compounds is not possible with the means offered by conventional water analysis if these substances are present together in dissolved form, since in the course of hydrolysis not only orthophosphates but also organic phosphate compounds are partially codetected. 

however, one can be certain that organic phosphates are not present it is possible to determine the inorganic phosphates by hydrolysis with subsequent determination as hydrogen phosphate. 

Two groups of hydrolyzable phosphates may be distinguished the (linear) polyphosphates with chain-like anions and the (cyclic) metaphosphates with ring-shaped anions. 

When dealing with problems of water treatment and corrosion protection, the determination of hydrolyzable phosphates is particularly important. As 

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