CLOUD POINT EXTRACTION OF MERCURY WITH PONPE 7.5 PRIOR TO ITS DETERMINATION IN BIOLOGICAL SAMPLES BY ETAAS

PEDRO R. ARANDA; RAÚL A. GIL; SUSANA MOYANO; IRMA E. DE VITO; LUIS D. MARTINEZ

TALANTA

Año: 2008 vol. 75 p. 307 - 311

0039-9140

Cloud point extraction (CPE) has been used for the pre-concentration of mercury, after the formation of a complex with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (5-Br-PADAP), and later analysis by electrothermal atomic absorption spectrometry (ETAAS) usingpolyethyleneglycolmono-p-nonyphenylether (PONPE 7.5) as surfactant. The chemical variables affecting the separation step were optimized.Under the optimum conditions, i.e, pH 8.5, cloud point temperature 80 ◦C, 5-Br-PADAP = 4×10−5mol L−1, PONPE 7.5 = 0.2%, sample vol-ume = 1.0mL, an enhancement factor of 22-fold was reached. The lower limit of detection (LOD) obtained under the optimal conditions was0.01gL−1. The precision for 10 replicate determinations at 2.0 gL−1Hg was 4.0% relative standard deviation (R.S.D.). The calibration graphusing the pre-concentration system for mercury was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least16gL−1. The method was successfully applied to the determination of mercury in biological samples and in certified reference material (QCMETAL LL3).© 2007 Elsevier B.V. All rights reserved.Keywords: Mercury; Pre-concentration; CPE–ETAAS; Microwave digestion; Human hair; Urine