Rapid differential flow injection of phosphorus compounds in wastewater by sequential spectrophotometry and inductively coupled plasma atomic emission spectrometry using a vacuum ultraviolet emission line

Abstract

A rapid and accurate flow analysis technique for the determination of total phosphorus and phosphate in wastewater is described. Phosphate was determined as molybdovanadophosphoric acid using a colorimetric method and the solution from the flow cell of the spectrophotometer was directly introduced to an inductively coupled plasma. The determination of total phosphorus was performed by measuring the emission intensity at 177.499 nm. The effect of the flow-rate and injection volume on emission signals was studied. The calibration graphs for phosphate and total phosphorus were linear up to 200 µg ml^–1 of phosphorus. The precision for 11 replicate measurements (200 µl of 10 µg ml^–1) was 2.01% relative standard deviation. Although chromium caused a positive error in colorimetric determination, no ions commonly existing in wastewater interfere with the determination of total phosphorus. Eighty samples can be analysed in an hour by this method. The proposed method was applied to the determination of phosphate and total phosphorus in wastewater and satisfactory results were obtained.