Characterization of a chelating resin functionalized via azo spacer and its analytical applicability for the determination of trace metal ions in real matrices

A selective flame atomic absorption spectrometric method has been developed for the determination of trace amount of metal ions after preconcentration on salicylic acid (SA) loaded Amberlite XAD-4 resin (AXAD-4) at suitable pH. The chelating resin AXAD-4-SA was characterized based on FTIR, thermal and chemical stability, and hydrogen ion capacity. The sorption capacity was found to be 245.0, 156.2, 155.0, 145.0, 125.0, 122.5, and 70 μmol g^-1 for Cu(II), Cr(III), Zn(II), Cd(II), Mn(II), Ni(II), and Co(II), respectively with t_1/2 <15 min. All the metals could be eluted by 5 mL of 4 mol L^-1 HCl/HNO₃ resulting in high preconcentration factor of 200-360 up to a low preconcentration limit of 5.5-10 μg L^-1. The accuracy and precision of the developed method was checked by analyzing standard reference materials. The experimental values were not statistically significant from the certified values with <5% RSD. The detection limits were found to be 0.42, 0.57, 0.63, 0.77, 0.94, 0.96, and 1.41 μg L^-1, respectively. The analytical utility of the AXAD-4-SA for preconcentration and determination of metal ions was explored by analyzing river, canal, sewage, and tap water by direct as well as standard addition method.