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On the Use of the Optothermal Window Technique for the Determination of Low Concentrations of Chromium (VI) and Phosphorus in Water

Abstract In this work we report about the use of the Optothermal Window (OW) technique, actually a variant of Photoacoustic Spectroscopy, combined with well-proven colorimetric methods to the determination of low concentrations of pollutants in water. As a first approach, chromium (VI) and phosphorus were determined in distilled water samples. The determination of Cr (VI) and P species in environmental and biological systems is currently of considerable interest due to the toxicity of their compounds to live organisms. Their maximum allowed values in drinking water were well discriminated in our experiments as well as the limits of optical spectrophotometric measurements. The detection limit in our measurements was 0.1 μmol/L P-PO4 3- for phosphorus at 632.8 nm and 0.2 μmol/L for chromium (VI) at 514 nm.