DETERMINATION OF LEAD IN NATURAL-WATERS USING FLOW-INJECTION WITH ONLINE PRECONCENTRATION AND FLAME AAS DETECTION

A rapid and sensitive method has been developed for the determination of lead in water samples by flame atomic absorption spectrometry using on-line preconcentration on a microcolumn packed with silica gel trea ted with a mixture of Aliquat 336 and nitroso-R-salt. The lead is reta ined at pH 5.5. The preconcentrated lead is directly eluted from the c olumn to the nebulizer-burner system using 150 muL of 0.1 mol/L hydroc hloric acid. The optimum preconcentration conditions are given and the retention efficiency achieved is higher than 80%. The enrichment fact or is 37 and 100 for sample volumes of 5 and 30 mL, respectively. The limits of detection are 10.0, 6.0 and 4.0 ng/mL when 5, 10 and 30 mL o f water is preconcentrated.