A Single-Solution Method for the Determination of Soluble Phosphate in Sea Water

Abstract

It has been found that a reagent containing sulphuric acid, ammonium molybdate and ascorbic acid may be used as a single-solution reagent for the determination of phosphate in sea water. Development of the molybdenum-blue colour is complete in 24 h at room temperature and in 30 min at 60° C; the colour is stable for at least 3 days. Beer's law is obeyed closely up to at least 500 μg PO 4 3− -P/1. The salt error is approximately 4% with sea water of chlorinity 19·3%. The interference due to either arsenate or silicate at their concentrations in sea water is negligible.