Considerations in the gas flow design of a graphite furnace vaporization interface: Effects of a halocarbon atmosphere and sample matrix. Invited lecture

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Abstract

A commercially available graphite tube furnace was coupled with an air-acetylene flame using two different designs of interface. The transverse sample introduction hole of the horizontal graphite tube was used as the exit for the evolved substances in one of the designs ('upward streaming'), while in the other version the vaporized product passed through one of the ends of the graphite tube ('end-on streaming'), the latter design being more generally applicable to plasma excitation-ionization sources (e.g., the inductively coupled plasma). Cadmium was selected as the test element as it is known that there are major changes in the transport efficiency of this element, in the presence of different matrices. Using fast heating (analytical conditions), the end-on streaming resulted in a 3-fold increase in integrated absorbance values for 20 ng of Cd, volatilized in an Ar atmosphere compared with upward streaming, and this factor decreased to 1.2 when using an atmosphere of Ar+CCl4 in the furnace. The signal enhancement factor due to the introduction of a halocarbon was 3.9 and 1.6 for upward and end-on streaming, respectively. The enhancement effect of 20 μg of Se (as Na2SeO4) without halogenation was 260 and 40%, and with halogenation it decreased to 21 and 12% for upward and end-on streaming, respectively (measured as the integrated absorbance for 20 ng of Cd). This means that the analytical performance was much better with end-on streaming in the absence of a halocarbon, but the difference in this respect decreased if CCl4 vapour was introduced. With the use of end-on streaming, the absorbance-time profile for Cd deteriorated with slow heating, owing to the re-vaporization of the partially condensed material from the end of the graphite tube. Therefore, the upward streaming system is recommended for use in volatilization studies (thermal evolution analyses).

Original languageEnglish
Pages (from-to)219-224
Number of pages6
JournalJournal of Analytical Atomic Spectrometry
Volume7
Issue number2
Publication statusPublished - 1992

Fingerprint

Halocarbons
Graphite
Vaporization
Flow of gases
Furnaces
Halogenation
Heating
Acetylene
Inductively coupled plasma
Ion sources
Cadmium
Vapors
Plasmas
Air

Keywords

  • Cadmium
  • Electrothermal vaporization
  • Graphite furnace
  • Halocarbon atmosphere
  • Interface design

ASJC Scopus subject areas

  • Spectroscopy

Cite this

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title = "Considerations in the gas flow design of a graphite furnace vaporization interface: Effects of a halocarbon atmosphere and sample matrix. Invited lecture",
abstract = "A commercially available graphite tube furnace was coupled with an air-acetylene flame using two different designs of interface. The transverse sample introduction hole of the horizontal graphite tube was used as the exit for the evolved substances in one of the designs ('upward streaming'), while in the other version the vaporized product passed through one of the ends of the graphite tube ('end-on streaming'), the latter design being more generally applicable to plasma excitation-ionization sources (e.g., the inductively coupled plasma). Cadmium was selected as the test element as it is known that there are major changes in the transport efficiency of this element, in the presence of different matrices. Using fast heating (analytical conditions), the end-on streaming resulted in a 3-fold increase in integrated absorbance values for 20 ng of Cd, volatilized in an Ar atmosphere compared with upward streaming, and this factor decreased to 1.2 when using an atmosphere of Ar+CCl4 in the furnace. The signal enhancement factor due to the introduction of a halocarbon was 3.9 and 1.6 for upward and end-on streaming, respectively. The enhancement effect of 20 μg of Se (as Na2SeO4) without halogenation was 260 and 40{\%}, and with halogenation it decreased to 21 and 12{\%} for upward and end-on streaming, respectively (measured as the integrated absorbance for 20 ng of Cd). This means that the analytical performance was much better with end-on streaming in the absence of a halocarbon, but the difference in this respect decreased if CCl4 vapour was introduced. With the use of end-on streaming, the absorbance-time profile for Cd deteriorated with slow heating, owing to the re-vaporization of the partially condensed material from the end of the graphite tube. Therefore, the upward streaming system is recommended for use in volatilization studies (thermal evolution analyses).",
keywords = "Cadmium, Electrothermal vaporization, Graphite furnace, Halocarbon atmosphere, Interface design",
author = "T. K{\'a}ntor",
year = "1992",
language = "English",
volume = "7",
pages = "219--224",
journal = "Journal of Analytical Atomic Spectrometry",
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T1 - Considerations in the gas flow design of a graphite furnace vaporization interface

T2 - Effects of a halocarbon atmosphere and sample matrix. Invited lecture

AU - Kántor, T.

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N2 - A commercially available graphite tube furnace was coupled with an air-acetylene flame using two different designs of interface. The transverse sample introduction hole of the horizontal graphite tube was used as the exit for the evolved substances in one of the designs ('upward streaming'), while in the other version the vaporized product passed through one of the ends of the graphite tube ('end-on streaming'), the latter design being more generally applicable to plasma excitation-ionization sources (e.g., the inductively coupled plasma). Cadmium was selected as the test element as it is known that there are major changes in the transport efficiency of this element, in the presence of different matrices. Using fast heating (analytical conditions), the end-on streaming resulted in a 3-fold increase in integrated absorbance values for 20 ng of Cd, volatilized in an Ar atmosphere compared with upward streaming, and this factor decreased to 1.2 when using an atmosphere of Ar+CCl4 in the furnace. The signal enhancement factor due to the introduction of a halocarbon was 3.9 and 1.6 for upward and end-on streaming, respectively. The enhancement effect of 20 μg of Se (as Na2SeO4) without halogenation was 260 and 40%, and with halogenation it decreased to 21 and 12% for upward and end-on streaming, respectively (measured as the integrated absorbance for 20 ng of Cd). This means that the analytical performance was much better with end-on streaming in the absence of a halocarbon, but the difference in this respect decreased if CCl4 vapour was introduced. With the use of end-on streaming, the absorbance-time profile for Cd deteriorated with slow heating, owing to the re-vaporization of the partially condensed material from the end of the graphite tube. Therefore, the upward streaming system is recommended for use in volatilization studies (thermal evolution analyses).

AB - A commercially available graphite tube furnace was coupled with an air-acetylene flame using two different designs of interface. The transverse sample introduction hole of the horizontal graphite tube was used as the exit for the evolved substances in one of the designs ('upward streaming'), while in the other version the vaporized product passed through one of the ends of the graphite tube ('end-on streaming'), the latter design being more generally applicable to plasma excitation-ionization sources (e.g., the inductively coupled plasma). Cadmium was selected as the test element as it is known that there are major changes in the transport efficiency of this element, in the presence of different matrices. Using fast heating (analytical conditions), the end-on streaming resulted in a 3-fold increase in integrated absorbance values for 20 ng of Cd, volatilized in an Ar atmosphere compared with upward streaming, and this factor decreased to 1.2 when using an atmosphere of Ar+CCl4 in the furnace. The signal enhancement factor due to the introduction of a halocarbon was 3.9 and 1.6 for upward and end-on streaming, respectively. The enhancement effect of 20 μg of Se (as Na2SeO4) without halogenation was 260 and 40%, and with halogenation it decreased to 21 and 12% for upward and end-on streaming, respectively (measured as the integrated absorbance for 20 ng of Cd). This means that the analytical performance was much better with end-on streaming in the absence of a halocarbon, but the difference in this respect decreased if CCl4 vapour was introduced. With the use of end-on streaming, the absorbance-time profile for Cd deteriorated with slow heating, owing to the re-vaporization of the partially condensed material from the end of the graphite tube. Therefore, the upward streaming system is recommended for use in volatilization studies (thermal evolution analyses).

KW - Cadmium

KW - Electrothermal vaporization

KW - Graphite furnace

KW - Halocarbon atmosphere

KW - Interface design

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