Determination of cadmium by FAAS after on-line enrichment using a mini column packed with Amberlite XAD-2 loaded with TAM

Abstract

A procedure for determination of trace amounts of cadmium with on-line preconcentration has been proposed. It is based on chemical sorption of cadmium(II) ions onto a minicolumn packed with Amberlite XAD-2 resin loaded with TAM reagent. After being preconcentrated, cadmium was eluted by 0.50 mol l−1 hydrochloric acid solution and straight determined on-line by flame atomic absorption spectrometry. A time-based technique was used. Chemical and flow variables as well as concomitant ions were studied in the developed procedure. Detection limit (3σ, n=22) was 1.2 μg l−1 for the analytical curve within the range of 0–200.0 μg l−1. An enrichment factor of 108 and a retention efficiency of 75.6% were achieved for a sample volume of 5.2 ml (1 min preconcentration time). The precision of the continuous preconcentration method, calculated as the relative standard deviation in sample solutions containing 10 μg l−1 of cadmium was 4 and 9%, regarding repeatability and reproducibility, respectively. The selectivity of the proposed procedure was also evaluated. Results showed that iron(III), zinc(II), nickel(II), manganese(II), aluminum(III), copper(II), lead(II), cobalt(II), chromium(VI) (200 μg l−1 concentration) did not interfere during cadmium determination (10.0 μg l−1concentration). Achieved analytical results for rice flour (NIES 10c) and lobster hepatopancreas (TORT-1) standard reference materials were in good agreement with the certified values. A high sample throughput (40 samples h−1), preconcentration factor and simplicity are the main advantages in this analytical procedure.