FI-Spetrophotometric Determination of Phosphate in Estuarine Water and Method of Correction for Salt Effect

A method of FI-spectrophotometry for the determination of phosphate in estuarine water was proposed. Salt effects, including refraction effect, matrix effect and kinetic effect, were discussed, and it was found that only refraction effect interfered with the determination. It was shown that this interference was avoided by adjusting the sample volume, reaction time, and time of integration. Linearity range was kept between 5.00-480 μg·L-1 of phosphate, with detection limit (3S/N) of 1.04 μg·L-1. The proposed method was applied to the analysis of estuarine water sample, giving value of RSD (n=7) of 1.4%, and value of average recovery of 100.4%.