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
Email: schalk@unf.edu
Website: @unf

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Hafnium

  • IUPAC Name: hafnium
  • Molecular Formula: Hf
  • CAS Registry Number: 7440-58-6
  • InChI: InChI=1S/Hf
  • InChI Key: VBJZVLUMGGDVMO-UHFFFAOYSA-N

@ ChemSpider@ NIST@ PubChem

Citations 6

"A Micro-scale Mercury Cathode Electrolysis Procedure For Online Flow Injection Inductively Coupled Plasma Mass Spectrometry Trace Elements Analysis In Steel Samples"
Anal. Chim. Acta 1999 Volume 389, Issue 1-3 Pages 247-255
Aurora G. Coedo, Isabel Padilla, Teresa Dorado and Francisco J. Alguacil

Abstract: An online matrix-analyte separation technique was developed for flow injection inductively coupled plasma mass spectrometry (FI-ICP-MS) trace analysis. A µelectrolytic cell was designed to be inserted in the FI manifold. The technique was used to separate Zr, Hf, Y, rare earth elements (REEs), Th and U from a steel-matrix (Fe, Cr, Ni, Co, Mn and Mo). A microwave-assisted HNO3-HCl-HF-H2SO4 digestion procedure, with temperature/pressure regulation, was used for sample dissolution. Obtained solutions were evaporated to SO3 fumes, and 2 mi of this diluted sulfuric solution were introduced in the electrolytic cell through the manifold circuit. After matrix removal, the electrolyte was conducted to load a 300 µl sample loop to be injected into the plasma torch. Direct multielement standard solutions in diluted sulfuric acid (without matrix matching and sample pretreatment) were applied for external calibration. The determination limits, with reference to the solid, were improved by a factor of about 10 compared with that obtained from direct measurements of 0.1% (m/v) sample solutions. The relative standard deviations for all the analytes were better than 3.5% for concentrations above 10 times the limit of quantification. The developed method was applied in the determination of certified elements in Steel Reference Materials: NIST 363 and NIST 364. Recoveries from 0.200 g test portions of high-purity iron spiked at two different concentration levels were found better than 97%.
NIST 363 NIST 364 Mass spectrometry Matrix removal Extraction

"Online Ion-exchange Separation And Determination Of Niobium, Tantalum, Tungsten, Zirconium, And Hafnium In High-purity Iron By Flow Injection Inductively Coupled Plasma Mass Spectrometry"
Anal. Chim. Acta 1995 Volume 315, Issue 3 Pages 331-338
Aurora G. Coedo*, Teresa D. López and F. Alguacil

Abstract: A study was made to investigate the feasibility of using an anion-exchange resin for on-line separation of trace amounts of niobium, tantalum, tungsten, zirconium and hafnium from iron matrix samples. The incorporation of a micro-column packed with Dowex 1X8-100 ion-exchange resin into a flow injection system is presented. The detection was done with inductively coupled plasma mass spectrometry (ICP-MS). The sample treatment, optimization of analytical variables and measurable concentration levels are discussed. Recoveries from standard additions to a high-purity iron were for all the analytes close to 100%, with relative standard deviations ranging from 0.7 to 3.0%. The limits of quantification (10 sn-1) calculated from a 5% (m/v) iron sample solution were 8, 5, 14, 12 and 10 ng g-1 for Nb, Ta, W, Zr and Hf, respectively. The accuracy of the proposed method was tested by determining these elements in Euronorm-CRM 098-1 reference material. Recoveries from 0.250 g test portions of the above reference material spiked with 2.5 and with 12.5 ng each of the five analytes are reported.
High purity Ion exchange Mass spectrometry

"An Optosensor Based On The Fluorescence Of Metal Complexes Adsorbed On Chelex 100"
Anal. Chim. Acta 1996 Volume 325, Issue 3 Pages 201-204
Zhilong Gong and Zhujun Zhang*

Abstract: The flow optosensor for Al(III), Ga(III), In(III), Zr(IV) and Hf(IV) was based of the formation of ternary complexes between the metal ion, quinolin-8-ol-5-sulfonate (QS) and Chelex 100. Metal ion solutions were diluted to 25 mL following the addition of 5 mL 0.1 M acetic acid/0.1 M sodium acetate buffer at pH 5.5 and 2 mL 1 mM QS and then pumped through a detection cell (20 µL) packed with Chelex 100 (200-400 mesh). The fluorescence intensity was monitored at the wavelengths of maximum excitation and emission for each metal ion and the metal ion concentration was calculated from the fluorescence at 30 s. Calibration graphs were linear from 0.02-50, 0.05-80, 0.08-80, 0.5-80 and 0.7-90 µM, respectively, for Al(III), Ga(III), In(III), Zr(IV) and Hf(IV) and the corresponding detection limits were 3, 5, 20, 20 and 30 nM. Most common metal ions did not interfere with the determination apart from Fe(III) which should be masked with 1,10-phenanthroline.
Fluorescence Sensor Chelex Interferences Complexation Indirect

"Flow System For Liquid Sample Introduction In Arc-spark Excitation Sources"
Analyst 1996 Volume 121, Issue 12 Pages 1923-1927
Carlos Roberto Bellato and Celio Pasquini

Abstract: A flow system, based on the monosegmented flow analysis approach, is described for the automated delivery of liquid samples to arc/spark excitation sources commonly used with plane grating spectrographs. The sample (50 µL) was carried between two air segments into the path of the excitation source via a hole drilled in a conventional graphite electrode. The arc/spark is applied to excite the sample for a pre-set time interval and the light emitted is integrated. A diagram of the flow system is given. The throughput was 25 samples/h. The flow system was used in the determination of Al, Pb and mixtures of Hf and Zr in aqueous solution (results presented and discussed).
Spectrophotometry Interface

"Optimization Of Operating Conditions For Improved Precision Of Zirconium And Hafnium Isotope Ratio Measurement By Inductively Coupled Plasma Mass Spectrometry (ICP-MS)"
J. Anal. At. Spectrom. 1995 Volume 10, Issue 2 Pages 99-103
Qianli Xie and Rob Kerrich

Abstract: The optimal instrument operating parameters (IOPs) for improving the precision of Zr and Hf isotope ratio measurements by inductively coupled plasma mass spectrometry (ICP-MS) were investigated, as an initial step towards improving precision in the determination of Zr and Hf abundances in samples with low concentrations of these elements by isotope dilution ICP-MS. An Elan Model 5000 ICP-MS was employed. Isotopes investigated were 90Zr, 91Zr, 92Zr, 94Zr, 177Hf, 178Hf, 179Hf and 180Hf. Varying the r.f. power from 1000 to 1300 W did not significantly affect the measured isotope ratios. Mass bias, always showing preferential reduction in response of light isotopes, occurred for both Zr and Hf isotope ratio measurements. Significant variations of measured isotope ratios were found as a function of ion lens setting and dwell time. Precision was optimized and mass bias minimized at a B lens setting of 60 digipots and a dwell time of 30 ms. The ratios 91Zr : 90Zr and 179Hf : 178Hf are the best for natural samples. Argid and oxide interferences on these masses are minimal; for example 162Dy16O and 163Dy16O translate into uncertainties of 0.02% in measured 179Hf : 178Hf ratios. By optimizing IOPs, it is not necessary to correct for potential interferences from rare earth element oxides, without sacrificing precision and accuracy of isotope ratio measurement. Precision and mass bias are insensitive to the concentration of Zr and Hf over the range of sub-ppb to ppm. An overall precision of 0.2-0.6% relative standard deviation can be achieved for Zr and Hf isotope ratio measurement, and can be maintained over 7 h periods.
Mass spectrometry Isotope ratio Precision Optimization

"The Determination Of Dissolved Zirconium And Hafnium From Seawater Using Isotope Dilution Inductively Coupled Plasma Mass Spectrometry"
Mar. Chem. 1998 Volume 60, Issue 3-4 Pages 245-255
Brad A. McKelvey* and Kristin J. Orians

Abstract: This paper describes the development of an analytical technique utilizing isotope dilution and inductively coupled plasma mass spectrometry (ICP/MS) to determine the picomolar and femtomolar concentrations of dissolved Zr and Hf found in seawater. Data acquired using this technique are presented to verify the method; in the subarctic North Pacific Zr ranges from 25 to 366 pmol/kg and Hf from 0.20 to 1.02 pmol/kg, with concentrations increasing smoothly with depth. The chelating ion-exchange resin, Chelex-100, was found to be suitable for the extraction/concentration step required for the determination of dissolved Zr and Hf in seawater using isotope dilution analysis. The extraction was optimized for pH, flow rate, resin volume, elution volume, and the time required for isotope equilibration. The isotope ratios 91Zr/90Zr and 178Hf/177Hf were measured using flow injection ICP/MS. The detection limits for a one litre sample are 0.21 and 0.03 pmol/kg for Zr and Hf, respectively. The analytical precision (1s) of the technique improves with increasing concentration and varies from 7% at 42 pmol/kg to 2.5% at 280 pmol/kg for Zr and from 22% at 0.28 pmol/kg to 9% at 1.4 pmol/kg for Hf.
Sea Mass spectrometry Mass spectrometry