Coupling of non-selective adsorption with selective elution for novel in-line separation and detection of cadmium by vapour generation atomic absorption spectrometry.

Abstract Non-selective adsorption of Cd 2+ ions on a cation exchange fiber and subsequent selective elution with a KI solution has been strategically utilized to develop a highly selective in-line separation of Cd 2+ ions from other metal ions for its rapid and reliable quantification by cold vapour-atomic absorption spectrometry. After retention of Cd 2+ with a high efficiency on cation exchange fiber, selective elution of the retained Cd 2+ was subsequently accomplished with 0.3 M KI. Vapour generation of Cd for in-line CV-AAS determination was then achieved by merging the eluate with HCl and NaBH 4 . Interferences from most base metals with the vapour generation of Cd were eliminated by this approach, with the exception of Pb 2+ ions which was removed by co-precipitation with BaSO 4 prior to the in-line separation. Substantial improvement in sensitivity of the in-line CV-AAS determination of Cd was achieved by increasing the sample loading time. A detection limit of 0.6 ng L −1 (3 σ ) was obtained with sample loading time of 120 s, corresponding to a consumption of 24 mL of sample solution. Application of the method to the determination of Cd in certified sediment and fish samples gave a good agreement with the certified values. Further validation by recovery study in real fish sample digests and water gave average Cd recoveries of 98.7±1.0% for fish and 92±3% for water with RSD of 1.5% for fish and 4% for water, respectively.