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

Elsevier

Año: 2008

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 graphite furnace atomic absorption spectrometry (GFAAS) using polyethyleneglicolmono-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 ~ 10−5 mol L−1, [PONPE 7.5] = 0.2%, added methanol volume = 1.0 mL, pre-concentration of 50 mL sample permitted an enhancement factor of 22-fold. The lower limit of detection (LOD) obtained under the optimal conditions was 0.01 ƒÊg L−1. The precision for 10 replicate determinations at 2.0 ƒÊg L−1 Hg was 4.0 % relative standard deviation (R.S.D.). The calibration graph using the pre-concentration system for mercury was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 16 ƒÊg L−1. The method was successfully applied to the determination of mercury in biological samples and in certified reference material (QC metal LL3).