Cloud Point Extraction, Preconcentration and Spectrophotometric Determination of Erbium(III)-2-(3,5-Dichloro-2-pyridylazo)-5-dimethylamino-phenol

M. F. SILVA; L. FERNÁNDEZ; R. OLSINA; D. STACCHIOLA

ANALYTICA CHIMICA ACTA

Elsevier

Año: 1997 vol. 342 p. 229 - 238

0003-2670

The extraction and preconcentration of metal chelates via surfactant-mediated phase separation was studied. The effects on extraction parameters of several experimental variables were evaluated. A successive approximation method, using a leastsquares computer program, was employed for the calculation of partition and acid dissociation constants of the chelating reagent. A new, high-sensitive and low-cost methodology for the determination of Er(III)-Z-(3,5-dichloro-Z-pyridylazo)-Sdimethylaminophenol - with the nonionic surfactant, polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5), with a cloud point extraction step prior to absorptiometric determination - was developed and optimized. Under the optimal experimental conditions, the molar absorptivity was 1.27 x 10? 1 mol-? cm-?. Calibration plot of absorbance (584 nm) vs. concentration was linear within the range 0.02-2 mg 1-l Er(III). The lower limit of detection (LOD) was 1.48x lo-? mol 1-l. The proposed procedure was successfully applied to the determination of Er(III) in synthetic samples, reproducing superconducting materials and permanent magnets.nm) vs. concentration was linear within the range 0.02-2 mg 1-l Er(III). The lower limit of detection (LOD) was 1.48x lo-? mol 1-l. The proposed procedure was successfully applied to the determination of Er(III) in synthetic samples, reproducing superconducting materials and permanent magnets.1-l Er(III). The lower limit of detection (LOD) was 1.48x lo-? mol 1-l. The proposed procedure was successfully applied to the determination of Er(III) in synthetic samples, reproducing superconducting materials and permanent magnets.