Flow injection preconcentration system using a new functionalized resin for determination of cadmium(II) by flame atomic absorption spectroscopy

Abstract

A rapid and sensitive method for the determination of trace level of Cd(II) in industrial effluents by flame atomic absorption spectroscopy has been developed. The technique is based on the online flow injection preconcentration of Cd(II) ions on a mini column, packed with Amberlite XAD-2 functionalized with xylenol orange. Flow injection variables have been optimized for the determination and quantitative preconcentration of Cd(II). Cd(II) ions are effectively retained on the mini column at <i style="mso-bidi-font-style:normal">p</i>H 5.0. A high sorption capacity of 348 µmol/g of dry resin is obtained and chelating resin can be reused for 70-80 cycles of sorption desorption without any significant change in the sorption capacity. With preconcentration times of 60 s and 120 s at a sample loading flow rate of 5 mL min^-1, preconcentration factors of 17 and 32 are obtained. The calibration graph using the preconcentration system for Cd(II) is linear over the concentration range of 0-120 µg L^-1. The precision for 5 replicate measurements are 1.68 and 1.12 for the determination of 20 and 50 µg L^-1Cd(II) respectively. The limits of detection obtained are 1.038 and 0.57 µg L^-1for 60 s and 120 s sorption time respectively. A sample throughput of 32 h^-1 is obtained with 5 mL of sample solution. Spiked recovery studies in water samples with certified Cd(II) nitrate solution traceable to NIST shows recovery in the range of 98-99 %. The accuracy of the developed online FI-FAAS procedure has been validated by analyzing cadmium(II) in standard reference material (SRM-1643e).