Modification for the FI-Photometric Method for Determination of Total Phosphate in Water

Manifold of a FI-photometric installation for determination of total phosphate in water was designed and fabricated. The mode of sample injection after digestion was changed to digestion after sample injection. Linear relationship between values of absorbance and mass concentration of total phosphate was obtained in the range of 0.01-2.0 mg·L-1, with detection limit (3S/N) of 1.4 μg·L-1. The proposed method was applied to the determination of total phosphate in water samples, giving values of recovery obtained by standard addition method in the range of 93.0%-105.0%. Analytical results by the present method were compared with those found by the GB method. As verified by t-test, no significant difference was found between the results found by the 2 methods.