Development of a flow method for the determination of phosphate in estuarine an...

• Author(s): Mesquita, Raquel B.R. ; Ferreira, M. Teresa S.O.B. ; Tóth, Ildikó V. ; Bordalo, Adriano A. ; McKelvied, Ian D. ; Rangel, António O.S.S.
• Date: 2011
• Persistent ID: http://hdl.handle.net/10400.14/7459
• Origin: Veritati - Repositório Institucional da Universidade Católica Portuguesa
• Subject(s): Sequential injection; Phosphate determination; Estuarine and river water; Spectrophotometry; Multireflective
• Document Type: Article
• Language: English

Description

A sequential injection system with dual analytical line was developed and applied in the comparison of two different detection systems viz; a conventional spectrophotometer with a commercial flow cell, and a multireflective flow cell coupled with a photometric detector under the same experimental conditions. The study was based on the spectrophotometric determination of phosphate using the molybdenumblue chemistry. The two alternative flow cells were compared in terms of their response to variation of sample salinity, susceptibility to interferences and to refractive index changes. The developed method was applied to the determination of phosphate in natural waters (estuarine, river, well and ground waters). The achieved detection limit (0.007 mM PO4 3−) is consistent with the requirement of the target water samples, and a wide quantification range (0.024–9.5 mM) was achieved using both detection systems.