Thermogravimetric investigations on the mechanism of decomposition of Pb compounds on a tungsten surface

Santos, Daniele Minholo; Luccas, Pedro Orival; Nóbrega, Joaquim A.; Cavalheiro, Éder Tadeu Gomes

doi:10.1016/s0040-6031(00)00578-5

Cited by 9 publications

(8 citation statements)

References 23 publications

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“…3,12,13 The importance of gas phase temperature and protecting gas composition for both WCAAS and WCAES is obvious from several works. [14][15][16] The severity of temperature gradients in a tungsten coil atomizer was emphasized in two different works, 17,18 with variations as significant as À250 K for each mm away from the coil surface. In another study, 19 Cu atomic absorption profile was determined and results suggested that both a high gas phase temperature and a reducing environment may positively affect WCAAS sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Development of a novel spectrometric-based temperature probe and the investigation of atomic cloud generation in a tungsten coil atomizer

Donati

Jones

2011

J. Anal. At. Spectrom.

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A new two-element atomic emission temperature probe is developed and applied to gas phase temperature determinations in both a tungsten coil atomizer and an air/acetylene flame. Results are comparable to the traditional Sn two-line method, with variances as low as 0.08%. The spectrometricbased thermometer is composed of a handheld spectrometer, a fiber optic and a laptop computer. The method is an interesting alternative for a wide range of applications due to its simplicity, portability and high temperature capabilities. Its spatial resolution is especially desirable for spectroscopic studies. An updated version of the Sn two-line method is used to determine the temperature profile of a tungsten coil atomizer and study processes involved in atomic cloud generation in both atomic absorption and atomic emission spectrometry. Tungsten coil atomizers present significant temperature gradients and spectrometric methods based on them are critically dependent on some interrelated parameters such as gas phase temperatures, protecting gas composition, and ultimately, atomizer positioning relative to the detector. Sn atomic absorption, and Li and Cr atomic emission profiles were determined and compared with the atomizer temperature profile. Elements determined by atomic emission are more dependent on gas phase temperatures while Sn absorption signal is more dependent on the reducing atmosphere provided by H 2 molecules present in the protecting gas mixture. Cr presents higher emission signals in a H 2 -rich, more reducing environment, whereas Li is less dependent on both temperature and protecting gas composition. Those results reflect Li lower excitation energy and Cr refractory characteristics.

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Section: Introductionmentioning

confidence: 99%

Development of a novel spectrometric-based temperature probe and the investigation of atomic cloud generation in a tungsten coil atomizer

Donati

Jones

2011

J. Anal. At. Spectrom.

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“…These crystals were characterized as metal-like and yellow in color, with high conductivity. While detailed studies on the effects of chemical modifiers have been reported for tungsten coil atomic absorption spectrometry, 23,24 a reasonable first approximation may be that the increased surface area resulting from these crystals may allow for better adhesion of analyte atoms during the heating program. While the investigation of the exact role of the surface effects on emission signal is beyond the scope of this manuscript, a conditioning program for new coils was developed.…”

Section: Coil Surface and Sensitivitymentioning

confidence: 99%

Simultaneous determination of the Lanthanides by tungsten coil atomic emission spectrometry

Donati

Nóbrega

et al. 2008

J. Anal. At. Spectrom.

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The fourteen Lanthanides are determined by tungsten coil atomic emission spectrometry. Twentyfive microlitre sample aliquots are placed directly on the coil. A simple constant current power source carefully dries the sample prior to analysis. During this dry step, the voltage is monitored to prevent over heating. This allows for shorter atomization programs, while improving sensitivity and coil lifetime. During the 5 s high temperature atomization step, the emission signals for as many as seven Lanthanides are determined simultaneously in the same 55 nm spectral window. The analytical figures of merit for all 14 natural Lanthanides are reported and compared with nitrous oxide flame atomic emission spectrometry. Tungsten coil atomic emission concentration detection limits are in the range 0.8 (Yb) to 600 (Pr) mg l À1 , and are lower than those for the flame in most cases. The absolute detection limits are near or below the ng level: significantly lower than the flame detection limits due to the smaller sample volume required. A three-fold improvement in detection limit may be realized by combining the signals for multiple emission lines for a single element. The method is applied to the determination of seven Lanthanides in a soil sample acquired from the National Institute of Standards and Technology. After a simple acid extraction, the measured values agree with the reported values with 95% confidence in all cases but one, Yb. Finally, a conditioning program for new tungsten coils enhances reproducibility and maximizes the emission signal.

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“…4b) is most likely caused by molecular absorption and radiation scattering due to species formed during the atomization of such a high concentration of the concomitant. While condensed-phase processes are known to cause this type of inter-element interference, [15][16][17][18] competition for H2 in the gas phase might also be a factor. Na atomization is known to depend upon the presence of H2, 18 and such a competition could explain the negative interferences on the Pb signal.…”

Section: Background Correctionmentioning

confidence: 99%

Analytical Characteristics of a Continuum-Source Tungsten Coil Atomic Absorption Spectrometer

et al. 2005

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Thermogravimetric investigations on the mechanism of decomposition of Pb compounds on a tungsten surface

Cited by 9 publications

References 23 publications

Development of a novel spectrometric-based temperature probe and the investigation of atomic cloud generation in a tungsten coil atomizer

Development of a novel spectrometric-based temperature probe and the investigation of atomic cloud generation in a tungsten coil atomizer

Simultaneous determination of the Lanthanides by tungsten coil atomic emission spectrometry

Analytical Characteristics of a Continuum-Source Tungsten Coil Atomic Absorption Spectrometer

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