Analytical Sciences

Determination of Cadmium in River Water Samples by Flame AAS after On-line Preconcentration in Mini-Column Packed with 2-Aminothiazole-modified Silica Gel

Ilton L. ALCÂNTARA,*¹ Paulo S. ROLDAN,*¹ Gustavo R. CASTRO,*¹ Fabrício V. MORAES,*² Fábio A. SILVA,*² Cilene C. F. PADILHA,*³ Jorge D. OLIVEIRA,*^1,*⁴ and Pedro M. PADILHA*²

*1 Instituto de Química, Departamento de Química Analítica-UNESP, P. O. Box 355, 14800-900, Araraquara, SP, Brasil
*2 Instituto de Biociência, Departamento de Química e Bioquímica-UNESP, P. O. Box 510, 18618-000, Botucatu, SP, Brasil
*3 Instituto de Biociências, Departamento de Física e Biofísica-UNESP, P. O. Box 510, 18618-000, Botucatu, SP, Brasil
*4 Universidade Estadual do Maranhão-CESI, 65901-480, Imperatriz, MA, Brasil

A rapid and sensitive method was developed to determine trace levels of Cd²⁺ ions in an aqueous medium by flame atomic absorption spectrometry, using on-line preconcentration in a mini-column packed with 100 mg of 2-aminothiazol modified silica gel (SiAT). The Cd²⁺ ions were sorbed at pH 5.0. The preconcentrated Cd²⁺ ions were directly eluted from the column to the spectrometer’s nebulizer-burner system using 100 µL of 2 mol L^-1 hydrochloric acid. A retention efficiency of over 95% was achieved. The enrichment factor (calculated as the ratio of slopes of the calibration graphs) obtained with preconcentrations in a mini-column packed with SiAT (A = -1.3 × 10^-3 + 1.8 × 10^-3[Cd²⁺]) and without preconcentrations (A = 4 × 10^-5 + 3.5 × 10^-5[Cd²⁺]), was 51 and the detection limit calculated was 0.38 µg L^-1. The preconcentration procedure was applied to determine trace levels of Cd in river water samples. The optimum preconcentration conditions are discussed herein.

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