Study of Digestion Efficiency on Spectrophotometric Determination of Phosphate in Water Sample by Flow Injection Analysis

Abstract

A method suitable for the determination of phosphate in water samples is presented. The flow injection (FI) manifold contain a PTFE reaction coil wrapped around a low power UV lamp and is based on the spectrophotometric determination of Orthophosphate and mineralized organic phosphate at 690 nm after reduction of phosphomolybdate to molybdenum blue with tin(II) chloride. The linear range was 0-1.5 mg L-1 P, with a detection limit (3 s) of 7 μg L-1 and a sample throughput of 40 h-1. The tolerance of interference from Fe(II), Al(III), and Fe(III) was achieved using on-line sample pre-treatment by a strong acid ion exchange colum