Spectrophotometric flow system using vanadomolybdophosphate detection chemistry and a liquid waveguide capillary cell for the determination of phosphate with improved sensitivity in surface and ground water samples

A flow injection procedure based on the vanadomolybdate method for the determination of dissolved reactive phosphorus in water samples is described. The system includes a liquid waveguide long pathlength cell connected to a charge coupled device (CCD) spectrophotometer. Calibration was linear up to 500 μg P L−1, with a detection limit of 17 μg P L−1 and a quantification limit of 56 μg P L−1. An injection throughput of 60 determinations h−1 and repeatability (R.S.D.) of 2.2% were achieved. Potential interference from silicate was effectively masked by addition of a tartaric acid stream. The accuracy of the proposed methodology was assessed through analysis of a certified reference material and recovery tests on water samples. The developed procedure allows the determination of phosphorus in water samples at trace levels with high sensitivity, reduced reagent consumption and low waste production.