On-line Preconcentration Of Cadmium Research Articles

Application of a Novel Sorbent Functionalized with 2-(5- Bromo-2-Pyridylazo)-5-Diethylaminophenol for On-line Preconcentration of Cadmium and Zinc

Application of a Novel Sorbent Functionalized with 2-(5- Bromo-2-Pyridylazo)-5-Diethylaminophenol for On-line Preconcentration of Cadmium and Zinc

DEVELOPMENT OF A SYSTEM FOR Cd PRE CONCENTRATION ON XAD-4 RESIN MODIFIED WITH FENILFLUORONA AND DETERMINATION BY ATOMIC ABSORPTION SPECTROMETRY

Cadmium is considered a potentially toxic element, since it doesn't perform any biological function and is highly cumulative. This element is usually found in environmental samples in very low concentrations. For this reason, there is a necessity to develop methods that allow sufficiently low detection limits. From this perspective, a simple, sensitive, selective and low cost methodology was developed for the determination of Cd by F AAS. The system involves the on-line pre concentration of cadmium onto a commercial polystyrene divinil benzene (PSDV) resin modified with phenylfluorone (PF). The experimental conditions (both chemical and physical) were optimized to achieve highest sensitivity. The modified resin had high chemical and physical resistance, and could be reused for 300 cycles without compromising the system's sensitivity. The obtained enrichment factor was around 8 times and accuracy, calculated as relative standard deviation (RSD), of 5.5% for cadmium concentration of 40 µg L-1. The limits of detection and quantification obtained were 0.15 and 0.49 µg L-1, respectively. This methodology proved to be applicable for samples of river waters, in which matrix interferences were not observed. In these samples recovery tests were conducted in order to evaluate the accuracy of the method, and these results varied between 89 and 118%.

Novel Functionalized Silica Gel for On-line Preconcentration of Cadmium(II), Copper(II), and Cobalt(II) with Determination by Flame Atomic Absorption Spectrometry

ABSTRACTSilica gel functionalized with 2-[N,N’-bis(2,3-dihydroxybenzaldimin)] aminoethylamine was employed as a novel sorbent for preconcentration of copper(II), cobalt(II), and cadmium(II) by flow injection-solid phase extraction. The pH of the analyte solution, sample and eluent flow rate, eluent volume, and the presence of concomitant ions were optimized. The limits of detection were 0.65, 0.52, and 1.42 µg/L and preconcentration factors were 12.3, 21.5, and 7.31 for cadmium(II), copper(II), and cobalt(II), respectively. The adsorption capacities of the functionalized silica gel for cadmium(II), copper(II), and cobalt(II) ions were 41.1, 31.7, and 26.5 mg/g. The preconcentration method was validated by determination of cadmium(II), copper(II), and cobalt(II) levels in Virginia Tobacco Leaves (CTA-VTL-2) and Water-Trace Elements (NWTM-15.2) certified reference materials. The method was also used to analyze water and food samples, and offers simplicity, reproducibility, high recovery, rapid and automated analysis, favorable ease of use, and low detection limits.

Salen impregnated silica gel as a new sorbent for on-line preconcentration of cadmium(II)

A new sorbent – salen impregnated silica gel – was prepared and characterised for application as a minicolumn packing for flow-injection on-line preconcentration of cadmium(II). The system was coupled with flame atomic absorption spectrometer (FI-FAAS). The optimal pH for Cd(II) sorption was in the range of 7.4–8.8 and nitric acid (1%, v/v) was efficient as eluent. Sorption was most effective within the sample flow rate up to 7 mL min−1. Sorption capacity of the sorbent found in a batch procedure was 26.3 µmol g−1 (2.95 mg g−1). Enrichment factor (EF) and limit of detection (LOD) obtained for 120-second loading time were 113 and 0.26 µg L−1, respectively. The sorbent stability in the working conditions was proved for at least 100 preconcentration cycles. The evaluated method was applied to Cd(II) determination in various water samples.

Highly sensitive pneumatic nebulization flame furnace atomic absorption spectrometry: complete sample aerosol introduction and on-line preconcentration of cadmium by atom trap

Complete introduction of sample aerosol into flame AAS is achieved by hyphenating pneumatic nebulization (PN) with flame furnace AAS (FF-AAS). The analyte solution is introduced via a pneumatic nebulizer into the flame heated furnace by a flow of carrier gas (air or argon). The middle part of the flame furnace, where the carrier gas impacts, is cooled by the gas flow as well as the sample aerosol, and this provides a fine strategy for on-line atom trapping for the purpose of preconcentration. A stainless steel plate is put on the top of the flame burner in the middle to form a flame-free zone, which also lowers the temperature of the flame furnace and facilitates the atom trapping process. Cadmium is selected as the analyte element because its low temperature atomization characteristic most suits for this approach. With 10 s preconcentration time (corresponding to 300 µL sample solution), a sensitivity enhancement factor of 730 (over conventional flame AAS) is obtained. The limit of detection for cadmium by the proposed method was found to be 15 ng L–1, comparable to that by graphite furnace AAS or chemical vapour generation atomic fluorescence spectrometry. This superior detectability originates from the atom trapping step involved in this simple and cost-effective approach.