Determination of Cr(VI) ions by flame AAS with preconcentration on Tris(2-aminoethyl)amine bonded silica gel using on-line column solid phase extraction technique

In this thesis, a new method was developed for the selective determination of Cr(VI) ions with flame atomic absorption spectrometry based on the preconcentration by the on-line column solid phase extraction technique using mini column filled with tris(2-aminoethyl)amine bonded silica gel (TRIS-SG). The effect of solution pH on the adsorption of Cr(III) and Cr(VI) ions on TRIS-SG was investigated by the batch method. When the pH of the solution containing Cr(III) and Cr(VI) ions was 1.0 and 2.0, Cr(VI) ions were selectively adsorbed on TRIS-SG. In the preconcentration of Cr(VI) ions with on-line column solid phase extraction technique, the effects of various parameters such as solution volume, type and volume of eluent solution, sample flow rate and volume and effect of matrix ions were investigated. Under the optimum conditions, the enrichment factor for Cr(VI) ions was 16.77 and the detection limit of the developed method (LOD) was found as 2.5 µg/L. The Cr(VI) levels in warious water samples were successfully determined using the developed method. In Cr(VI) adsorption studies performed by batch method, Cr(VI) adsorption capacity of TRIS-SG was calculated as 48.8 ± 2.1 mg/g.