Direct combination of thermogravimetric analyser and atomic absorption spectrometer for detection of atomic vapour in thermal analysis

Nagayama, Kazuyuki; Takada, Takeo

doi:10.1016/0040-6031(89)87166-7

Cited by 7 publications

(7 citation statements)

References 6 publications

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“…By varying the temperature of the GF, the temperaturedependence of the diffusion process can also be assessed. L'vov [60] earlier drew attention to the problem [60,61] Measurement of bulk diffusion of metal vapors in graphite [54] Measurement of oscillator strengths [63,64] Measurement of heat of vaporization of refractory metals [66,67] Measurement of desorption energies of surface ad-atoms [68][69][70][71] Study of high-temperature reaction mechanisms [72,73] Study of phase transitions in solids [74][75][76] of high-temperature metal vapor diffusing through the porous walls of his graphite cuvette and pointed out the need to have the GF coated with a more impervious layer of pyrolytic graphite. Styris [54] measured the effective bulk diffusion coefficients of a number of metal vapors passing through porous graphite at high temperature using mass spectrometric detection.…”

Section: Physico-chemical Applications Of the Gfmentioning

confidence: 99%

“…The spectroscopic technique of shadow spectral filming proposed by Gilmutdinov [73] also possesses a number of attributes which make it a useful tool in combination with sample atomization in the GF to aid the elucidation of hightemperature reaction mechanisms. In a similar manner, the use of MS as a detection system for the monitoring of species evolving from heated samples at low temperatures will aid in the confirmation of high-temperature precursor species, as for example the combination of thermogravimetric measurements with MS or simply with real time AAS data [74]. Phase transitions in solids can be investigated with GF-AAS [75] techniques and the use of a pressure regulated GF-AAS system to aid in the separation of the analyte generation function from the loss process has proved useful for the characterization of diffusion in solids and the speciation of bulk, surface and grain-boundary deposits of analyte within solids [76].…”

Section: Physico-chemical Applications Of the Gfmentioning

confidence: 99%

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The graphite furnace and its role in atomic spectroscopy

Sturgeon

1996

Analytical and Bioanalytical Chemistry

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The diversity of applications of the graphite furnace is extraordinary, encompassing the fields of physics, thermochemistry, spectroscopy and analytical chemistry. In this respect, the graphite furnace has been used on a continuous basis as a research tool for nearly a century. Following its introduction as an atomization source for atomic absorption spectrometry by L'vov in 1959, its role in atomic spectrometry expanded considerably to encompass analytical applications in emision, fluorescence, absorption and mass spectrometry. In addition to its conspicuous use as an atomization source in these areas, it is frequently employed as a vaporizer when used in the format of combined and tandem sources with other instrumentation. The unique physico-chemical micro-environment which can be attained within the graphite furnace has also been used to advantage in a number of investigations, including the determination of gas- and solid-phase diffusion coefficients of high-temperature metal vapours, the heats of sublimation of refractory metals, fundamental optical constants and the measurement of the heats of desorption of adatoms from high-temperature surfaces. The range of such applications remains to be more fully explored. The attractive features of this source, viz., the high atomization/vaporization efficiency, comparatively long atomic vapour residence times, controllable chemical and thermal environment and its ability to handle high dissolved solids content samples (

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Section: Physico-chemical Applications Of the Gfmentioning

confidence: 99%

Section: Physico-chemical Applications Of the Gfmentioning

confidence: 99%

The graphite furnace and its role in atomic spectroscopy

Sturgeon

1996

Analytical and Bioanalytical Chemistry

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“…L'vov and Kocharova (18) calculated correction factors to account for the effect of hyperfine structure on signal amplitude. A potentially useful system for fundamental studies in AAS was a combined thermogravimetric analyzer and AA spectrometer (19), which allowed AA signals and thermogTavimetric changes to be monitored simultaneously. Another useful diagnostic technique may be impedance atomic spectroscopy (20), based on laser-induced changes in the dielectric constant of the gases in an atom cell.…”

Section: B Fundamental Datamentioning

confidence: 99%

Atomic absorption, atomic emission, and flame emission spectrometry

Jackson¹,

Qiao²

1992

Anal. Chem.

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“…HgCl 2 (s) is very volatile and its vapor pressure is well established [2,9,10]. This increases rapidly in the 150-250 • C range (3 × 10 −3 atm., 150 • C; 0.1, 228 • C; 0.2, 246 • C), with a boiling point of about 300 • C. Thermogravimetric measurements for HgCl 2 clearly indicate this rapid sublimation [11], and an attached atomic absorption analyzer confirmed the molecular nature of the vaporization [12]. No evidence was indicated for the presence of free Hg atoms while the mass decreased.…”

mentioning

confidence: 92%

Comment on Ernest et al. Programmable Thermal Dissociation of Reactive Gaseous Mercury, A Potential Approach to Chemical Speciation: Results from a Field Study. Atmosphere 2014, 5, 575–596

Schofield

2016

Atmosphere

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The authors of this paper utilized a so-called "programmable thermal dissociation method" to monitor HgCl 2 emitted from a coal-fired Florida combustion plant. By comparison, they did confirm that the emitted mercury compound was in fact the dichloride, which is in fact the only such plausible molecule for mercury. However, the subtle implications in the paper that the HgCl 2 (g) molecule is not thermally stable and can readily dissociate in the gas phase at temperatures below 300 • C is not consistent with a very broad spectrum of chemical information and clearly can be misleading and incorrect if not more fully explained.Unlike elemental mercury, its dichloride is known as a corrosive sublimate and it is soluble in water. Its heat of formation and heat of vaporization are well known, providing a gas-phase heat of formation that indicates an atomization energy D 0,Atomization (HgCl 2 ) g = 445 ± 5 kJ·mol −1 [1,2], supported also by theory [3]. The monohalide, HgCl(g), is well characterized and known to be very weakly bound, with D 0 (HgCl) = 96 ± 8 kJ·mol −1 (experimentally) [4,5] and 94 kJ·mol −1 (theoretically) [3,6,7]. Coupling these values implies the ClHg-Cl bond in HgCl 2 (g) has a bond strength of about 350 kJ·mol −1 . This is a significant strength and clearly indicates the unequal strengths of the two bonds. Its stability is the reason, in chemical equilibrium calculations describing combustion, why it is predicted that elemental Hg should be negligible and HgCl 2 (g) dominant [8]. The fact that it is not is due to the kinetic and time constraints on the formation mechanisms converting Hg to HgCl 2 . Nevertheless, the thermodynamic calculations illustrate its bond strength and that it should be thermally stable below 500 • C, above which it does begin to thermally dissociate or be hydrolyzed by any gaseous water present. HgCl 2 (s) is very volatile and its vapor pressure is well established [2,9,10]. This increases rapidly in the 150-250 • C range (3 × 10 −3 atm., 150 • C; 0.1, 228 • C; 0.2, 246 • C), with a boiling point of about 300 • C. Thermogravimetric measurements for HgCl 2 clearly indicate this rapid sublimation [11], and an attached atomic absorption analyzer confirmed the molecular nature of the vaporization [12]. No evidence was indicated for the presence of free Hg atoms while the mass decreased. The confusion has arisen from mercury's ability under certain conditions to release atomic mercury in nature from its molecules not only from oceanic sources but also from vegetation and soils [13,14]. This also has been apparent when HgCl 2 is absorbed into mixtures such as quartz, pyrex or ceramic wool, or activated charcoal [15], or may happen from the gypsum produced from combustor flue gas desulfurizers [16]. Although studied for many years, the mechanism for this chemical reduction and release still remains unknown [17,18].In relation to coal combustion, this laboratory has monitored the induced conversion of Hg(g) to HgCl 2 (g) on passing coal-fired flue gases through a non-catalytic honeyco...

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Direct combination of thermogravimetric analyser and atomic absorption spectrometer for detection of atomic vapour in thermal analysis

Cited by 7 publications

References 6 publications

The graphite furnace and its role in atomic spectroscopy

The graphite furnace and its role in atomic spectroscopy

Atomic absorption, atomic emission, and flame emission spectrometry

Comment on Ernest et al. Programmable Thermal Dissociation of Reactive Gaseous Mercury, A Potential Approach to Chemical Speciation: Results from a Field Study. Atmosphere 2014, 5, 575–596

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