Resumo

LESCANO, E; BARREIRO, N  e  SLEZAK, V. Pulsed thermal lens technique for Cr(VI) traces detection in water. An. AFA [online]. 2015, vol.26, n.3, pp.113-117. ISSN 0327-358X.

The detection of heavy metals in water coming from natural and anthropogenic sources is of great interest all over the world because it can affect human life as well as aquatic and terrestrial organisms. In particular, Cr(VI) is a metal produced in many industrial processes and exposure to it can be lethal. In this sense, it is important to develope a selective technique which allows Cr(VI) detection with low detection limit. In this work we propose the use of thermal lens spectroscopy in collineal dual-beam mismatched configuration, for the detection of Cr(VI) in samples with DPC, which increases and shifts to the green part of the spectrum its absorption peak. For this, we used for excitation a pulsed dye laser tuned by means of a diffraction gratting at the absorption maximum of the Cr(VI)-DPC complex at 540 nm and a probe diode laser at 635nm. This work shows the optimization of the system and its calibration obtaining a detection limit of 0.004 mg/l. Next, we applied the system to measure water samples of Reconquiesta River and sink water obtaining low Cr(VI) concentrations compared to the maximum allowed by the World Health Organization (0.05 mg/l).

Palavras-chave : Thermal Lens; Environmental analysis; Hexavalent chromium.

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