Spectrophotometric determination of chromium in steel with 4-(2- thiazolylazo)-resorcinol (TAR) using microwave radiation

Journal of the Brazilian Chemical Society

Luciene S. De Carvalho¹  Antônio Celso S Costa¹  Sérgio L. C Ferreira¹  Leonardo S. G Teixeira¹ 

[1] ,Universidade Federal da Bahia Campus Universitário da Federação Instituto de QuímicaSalvador BA ,Brazil

关键词: chromium;    TAR;    spectrophotometric;    microwave radiation;    steel;   

DOI  :  10.1590/S0103-50532004000100025

来源: SciELO

【 摘 要 】

A spectrophometric method for the determination of Cr(III) with 4-(2- thiazolylazo)-resorcinol was developed. Cr(III) slowly forms a red complex with TAR at pH 5.7. Irradiating the reacting mixture with microwave energy can accelerate the complex formation. The absorbance reached its maximum with 5 min of irradiation and remained stable, at least, for 24 h. N-cetyl-N,N,N-trimethylammonium bromide (CTAB) was used for increasing the sensitivity and solubility of the system. The method allowed the determination of chromium ranging from 0.050 to 3.0 mg mL-1 (9.62 x 10-7 to 5.77 x 10-5 mol L-1) with a molar absorptivity of 2.73x10(4) L-1 mol-1 cm-1 and a detection limit of 17 ng mL-1 (3.3 x 10-7 mol L-1) at 545 nm. The selectivity was improved by using EDTA and citrate as masking agents. Fe(III) interferes and must be extracted previously, if present in the sample. The proposed method has been successfully applied to the determination of chromium in steel. The precision (R.S.D. < 2%) and accuracy were satisfactory.

【 授权许可】

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