Application of modified simplex on the development of a preconcentration system for cadmium determination in sediments, food and cigarettes

摘要

A modified simplex algorithm was used to optimize a system of preconcentration for cadmium determination in samples of sediments, cigarettes and food using flame atomic absorption spectrometry. The preconcentration system is based on the sorption of cadmium in a minicolumn packed with Amberlite XAD-2 resin functionalized with 3,4-dihydroxybenzoic acid (DHB). The optimized variables were pH and sampling flow rate and the optimum conditions found for these variables were, respectively 8.7 and 8.8 mL min -1 . The developed system showed a preconcentration factor of 15.3, detection limit of 0.49 ?μg L -1 , quantification limit of 1.65 ?μg L -1 and precision expressed as relative standard deviation (% RSD, n=10) of 5.9. The accuracy of the method was checked by analysis of estuary sediment certified reference material (NIST 1646-1). The cadmium concentrations found in sediment samples ranged from 1.73 and 1.90 ?μg g -1 . In cigarette samples the results were 0.085 and 0.193 ?μg g -1 , and in food samples (coriander and lettuce) the concentrations found of this metal were, respectively, 0.33 and 0.12 ?μg g -1 .