Development and optimization of analytical method for the determination of cadmium from mineral water samples by off-line solid phase extraction system using sisal fiber loaded TAR by FAAS

Abstract

In the present work, a minicolumn of sisal fiber loaded with tiazolylazo-Resorsinol (TAR) is proposed a preconcentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. In the optimization was first of all a full factorial design of two levels (24) was used for preliminary evaluation of four factors, involving the variables: sampling flow rate, elution flow rate, buffer concentration and pH. This design has showed that, for the studied levels, buffer concentration and pH are significant factors. Using the established experimental conditions in the optimization step of: pH 7.0, buffer concentration of 0.009mol L−1 for elution utilized HCl at 2.0mol L−1, this system allows the determination of cadmium with a detection limit (LD) (3σ/S) of 0.05μg L−1 and a quantification limit (LQ) (10σ/S) of 0.17μg L−1, precision expressed as a relative standard deviation (R.S.D.) of 2.9 and 3.4% for a cadmium concentration of 10.0 and 20.0μg L−1, respectively, and a preconcentration factor of 30 for a sample volume of 50.0mL. The accuracy was confirmed by cadmium with spike tests with recuperations varying from 92% to 103%, procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. From the five samples analyzed, the achieved concentrations varied from 0.10 to 0.54μgL−1.