Resumen

DORIA HERRERA, Gloria María; PAZ ORDONEZ, Paulo Andrés  y  HORMAZA ANAGUANO, Angelina. Standardization of diphenylcarbazid as an indicator and a complexity factor in the identification of chromium hexavalent - Cr (VI). Rev. P+L [online]. 2013, vol.8, n.2, pp.9-20. ISSN 1909-0455.

Introduction. The treatment of water polluted with metals has gained a great importance in history, as the presence of such water not only generates a nasty visual impact, but also affects the ecosystems. One of the most toxic and stable metals in solution is Cr (VI). Its identification and quantification are very important, and so is its removal. Among the analysis techniques, colorimetry is one of the most economic and efficient to identify this metallic ion in solution, thanks to the action of the 1, 5-diphenylcarbazid, which allows an exact determination of its presence in solution. Objective. To establish the best conditions to implement 1, 5- diphenylcarbazid as a complexity agent to determine Cr (VI) in solution. Materials and methods. The best work conditions were assessed by elaborating the calibration curves, identification of extinction coefficients, effect of the dissolvent, detection-quantification limit and degradation kinetics, after the action of the complexity agent. The determinations were performed with the UV- visible spectrophotometry technique. Results. The calibration curves obtained satisfactory results (99.11 %, 97.35 % and 99.17 %) with 95 % of confidence. The detection limit determined is 0.096 ppm and the quantification limit is 0.35 ppm. These results are very satisfactory, given the sensibility of the technique. The effect of the dissolvent with acetone, methanol and ethanol showed small batochromic displacements and a good correlation. Conclusion. 1, 5-diphenylcarbazid is an adequate complexity agent to determine Cr (VI) in solution.

Palabras clave : diphenylcarbazid; complexity; chromium; metals; quantification; Uv-visible spectrophotometry.

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