University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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BCR 320

Classification: Reference Material -> BCR -> 320 -> River sediment

Citations 2

"Coupling On-line Preconcentration By Ion-exchange With ETAAS. A Novel Flow Injection Approach Based On The Use Of A Renewable Microcolumn As Demonstrated For The Determination Of Nickel In Environmental And Biological Samples"
Anal. Chim. Acta 2000 Volume 424, Issue 2 Pages 223-232
Jianhua Wang and Elo Harald Hansen

Abstract: A novel way of exploiting flow injection/sequential injection (FIA/SIA) on-line ion-exchange pre-concentration with detection by electrothermal atomic absorption spectrometry (ETAAS) is described and demonstrated for the determination of trace-levels of nickel. Based on the use of a renewable microcolumn incorporated within an integrated µFI-system, the column is loaded with a defined volume of small beads of an SP Sephadex C-25 cation-exchange resin and subsequently exposed to a metered amount of sample solution. However, instead of eluting the retained analyte from the organic ion-exchange resin, the beads are along with 30 µL of carrier (buffer) solution transported via air segmentation directly into the graphite tube, where they are ashed during the pyrolysis and atomization process. The ETAAS determination is performed in parallel with the pre-concentration process of the ensuing sample. An enrichment factor of 72.1, a detection limit of 9 ng L-1, along with a sampling frequency of 12 h-1 were obtained with 150 s of sample loading time at a sample flow rate of 12 µL s-1 (corresponding to 0.72 mL min-1). The relative standard deviations were 3.4%. The procedure was validated by determination of the nickel contents in two certified reference materials and in a human urine sample.
Nickel Spectrophotometry Reference material Solvent extraction Preconcentration Column Sephadex Sequential injection Interferences Optimization

"Determination Of Thallium In River Sediment By Flow Injection Online Sorption Preconcentration In A Knotted Reactor Coupled With Electrothermal Atomic Absorption Spectrometry"
Analyst 1997 Volume 122, Issue 7 Pages 667-671
Elissaveta Ivanova, Xiu-Ping Yan, Willy van Mol and Freddy Adams

Abstract: Sediment was digested by heating with HNO3/HF and then with HClO4. Aqueous bromine (up to 0.3%) was added to the final solution, which was made 2 M in HNO3. The resulting solution was pumped (4.8 ml/min) and mixed with a reagent stream (1.3 ml/min) of 0.05% ammonium pyrrolidinedithiocarbamate (APDC) before being loaded into a knotted PTFE reactor (100 cm x 0.5 mm i.d.). After a 30 s pre-concentration time, the reactor was washed with 0.1% H2SO4 and the Tl-APDC chelate was eluted with 45 µL ethanol (a diagram of the manifold used and details of the operating sequences employed are given). The eluate was analyzed for Tl by ET AAS at 276.8 nm using an Ir-modified graphite tube and pyrolysis and atomization temperatures of 600 and 1300°C, respectively (other operating conditions tabulated). The calibration graph was linear for 0.05-1.5 µg/l Tl, the detection limit was 15 ng/l and the RSD (n = 11) was 2.9%. The throughput was 26 samples/h. A flow injection online sorption pre-concentration electrothermal atomic absorption spectrometric (ETAAS) method mas developed for the determination of thallium, The Tl3+-tetramethplenedithiocarbamate (pyrrolidinedithiocarbamate) complex formed in strongly acidic medium (0-3 mol L-1 HNO3, 0-3 mol L-1 H2SO4, 0-2.5 mol L-1 HClO4 or 0-2 mol L-1 HCl) is sorbed on the inner malls of a PTFE knotted reactor (100 cm x 0.5 mm id) and quantitatively eluted with 45 µl of ethanol, The ETAAS determination is performed in parallel with the pre-concentration of the next sample, Using a pre-concentration time of 30 s and a sample loading rate of 4.8 mi min-1, an enhancement factor of 27 is obtained in comparison with direct injection of 45 pi of aqueous solution, The adsorption efficiency is 51%. The detection Limit (3s) is 0.015 µg L-1 and the precision (RSD) is 2.9% for 0.4 µg L-1 TI (It = II), The accuracy of the method is demonstrated by the analysis of a Community Bureau of Reference certified reference material 320 river sediment (indicative value for thallium concentration). 30 References
Thallium Sample preparation Spectrophotometry Preconcentration Knotted reactor Reference material Complexation Interferences