A Critical Study on the Methods of Water Analysis. V

On the Determination of Phosphate

Abstract

Denigès-Atkins' method of the determination of phosphate is discussed here.
1) The author has prepared the stannous chloride solution from pure SnCl₂2H₂O instead of dissolving a tin foil in hydrochloric acid. No differences are found between these two reagents in their reducing actions of phospho-molybdate.
2) There is a marked influence which reduces the amount of phosphate, when silicate is present more than 15mg./l. with respect to SiO₂ On the contrary, influences by chloride and iron are quite neglegible, except the colour tint becomes somewhat yellowish, but this is easily eliminated with a yellow glass filter.