Use of Al2O3 in an automated on-line pre-concentration system for determination of cadmium(II) by FAAS

This paper presents the development of an on-line pre-concentration system to determine cadmium(II) in aqueous samples. The analyte was trapped in a mini-column filled with Al2O3 in the form of macro-spheres obtained by the mixture of Al(NO3)3·9H2Oaq and chitosan dissolved in acetic acid. The mixture was dropped into an NH4OH aqueous solution under rigorous agitation using a peristaltic pump, the macro-spheres were separated from alkaline solution and dried, and finally were submitted to thermal treatment. The pre-concentration system was linear between 1.0 and 100 μg L−1, with a linearity of 0.999, sensitivity of 3.58 × 10−3 L μg−1 and enrichment factor of 21.9. The limits of detection and quantification were 0.08 μg L−1 and 0.28 μg L−1, respectively. The repeatability was between 2.6 and 5.9%. Recovery tests were carried out with a real aqueous sample.