On the use of the optothermal window technique for the determination of low concentrations of chromium (VI) and phosphorus in water

In this work we report about the use of the Optothermal Window (OW) techniq ue, actually a variant of Photoacoustic Spectroscopy, combined with well-pr oven colorimetric methods to the determination of low concentrations of pol lutants in water. As a first approach, chromium (VI) and phosphorus were de termined in distilled water samples. The determination of Cr (VI) and P spe cies in environmental and biological systems is currently of considerable i nterest due to the toxicity of their compounds to live organisms. Their max imum allowed values in drinking water were well discriminated in our experi ments as well as the limits of optical spectrophotometric measurements. The detection limit in our measurements was 0.1 mu mol/L P-PO43- for phosphoru s at 632.8 nm and 0.2 mu mol/L for chromium (VI) at 514 nm.