Determination of cadmium at ultra-trace levels by CPE-molecular fluorescence combined methodology.
A highly sensitive micelle-mediated extraction methodology for the preconcentration and determination of trace levels of cadmium by molecular fluorescence has been developed. Metal was complexed with o-phenanthroline (o-phen) and eosin (eo) at pH 7.6 in buffer Tris medium and quantitatively extracted into a small volume of surfactant-rich phase of PONPE 7.5 after centrifugating. The chemical variables affecting cloud point extraction (CPE) were evaluated and optimized. The RSD for six replicates of cadmium determinations at 0.84 microg L(-1) level was 1.17%. The linearity range using the preconcentration system was between 2.79 x 10(-3) microg L(-1) and 2.81 microg L(-1) with a correlation coefficient of 0.99. Under the optimal conditions, it obtained a LOD of 8.38 x 10(-4) microg L(-1) and LOQ of 2.79 x 10(-3) microg L(-1). The method presented good sensitivity and selectivity and was applied to the determination of trace amounts of cadmium in commercially bottled mineral water, tap water and water well samples with satisfactory results. The proposed method is an innovative application of CPE-luminescence to metal analysis comparable in sensitivity and accuracy with atomic spectroscopies.
Talio
María Carolina
MC
Instituto de Química de San Luis-CONICET, Chacabuco y Pedernera, 5700 San Luis, Argentina.
Luconi
Marta O
MO
Masi
Adriana N
AN
Fernández
Liliana P
LP
D002104:Cadmium / Q000032:analysis*; D002498:Centrifugation; D002614:Chelating Agents; D004801:Eosine Yellowish-(YS); D005453:Fluorescence; D005456:Fluorescent Dyes; D005618:Fresh Water / Q000737:chemistry; D008722:Methods; D008823:Micelles; D010618:Phenanthrolines; D015203:Reproducibility of Results; D013501:Surface-Active Agents; D014131:Trace Elements / Q000032:analysis; D014881:Water Supply / Q000032:analysis
D002614:Chelating Agents; D005456:Fluorescent Dyes; D008823:Micelles; D010618:Phenanthrolines; D013501:Surface-Active Agents; D014131:Trace Elements; D002104:Cadmium; D004801:Eosine Yellowish-(YS); C025205:1,10-phenanthroline