University of North Florida
Browse the Citations
-OR-

Contact Info

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

View Stuart Chalk's profile on LinkedIn

BCR 176

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 Arsenic And Vanadium In Airborne Related Reference Materials By Inductively Coupled Plasma-mass Spectrometry"
Anal. Chim. Acta 1999 Volume 392, Issue 2-3 Pages 299-306
Chu-Fang Wang, C. Y. Chang, C. J. Chin and L. C. Men

Abstract: This study investigated sample digestion techniques and instrumental interference in determining As and V in airborne related reference materials using inductively coupled plasma mass spectrometry (ICP-MS). Four reference materials, NIST SRM 1648 urban particulate matter, BCR Reference Material No. 176 city waste incineration ash, NIST SRM 2709 San Joaquin soil, and NIST SRM 1633b coal fly ash were dissolved by acid mixture high-pressure bomb digestion. A HNO3+H2O2+HF mixed acid digestion with a low temperature evaporation procedure is proposed as an effective sample pretreatment method for the determination of As in all samples. The addition of HF is required especially for dissolving geologically originated samples such as soil or dust. It was found that, with the proposed digestion procedure, the determinations of V are still unacceptable for highly chlorinated samples when using quadrupole ICP-MS. It was also proved that sector-field ICP-MS is sufficiently sensitive for the determination of V, and can be utilized as a valid tool to investigate the amount and direction of biased results obtained from ICP-MS.
Arsenic Vanadium Mass spectrometry Optimization Interferences Reference material