Graphite atomizers modified with high-melting carbides for electrothermal atomic absorption spectrometry. II. Practical aspects

Volynsky, Anatoly B.

doi:10.1016/s0584-8547(98)00221-3

Cited by 59 publications

(26 citation statements)

References 233 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, evaluation of the surface activity seems to be impossible, because it depends both on the nature and the composition of carbides and the structure of the carbide layer. The actual reason for the improved sensitivity of thallium in the case of the W-coated tube can be explained by more efficient dissociation of Tl 2 O [27]. The formation of tungsten carbides on the graphite surface was studied in detail by controlled decomposition of (NH 4 ) 2 WO 4 mixed with the graphite RW-A (SGL CARBON GmbH, Germany), used for the tube manufacture.…”

Section: Resultsmentioning

confidence: 99%

Slurry sampling for the determination of thallium in soils and sediments by graphite furnace atomic absorption spectrometry

Dobrowolski

2002

Anal Bioanal Chem

View full text Add to dashboard Cite

The analytical conditions for thallium determination in soils and sediments by slurry sampling graphite furnace atomic absorption spectrometry were studied and optimized. Elimination of a strong background for soils rich in organic materials by application of tungsten carbides coated graphite tubes/platforms was studied in detail. Tungsten carbides increased the maximum permissible pyrolysis temperature from 300 to 900 degrees C. The mechanism of tungsten carbide formation on different graphite surfaces was proposed. Application of a strong basic anion-exchange resin for interference elimination in thallium determination in marine sediments was described. Calibration was performed directly using aqueous standards both for soil and sediment analysis. Analysis of CRM confirmed the reliability of the approach. The precision and accuracy of thallium determination by the described method for soils and sediments was acceptable. A characteristic mass of 13.8 pg was obtained and the limit of detection for the proposed method was around 0.06 microg g(-1) Tl.

show abstract

Section: Resultsmentioning

confidence: 99%

Slurry sampling for the determination of thallium in soils and sediments by graphite furnace atomic absorption spectrometry

Dobrowolski

2002

Anal Bioanal Chem

View full text Add to dashboard Cite

show abstract

“…The modifying properties of tungsten [1][2][3][4][5][6][7][8] are often used in atomic absorption spectrometers (AAS) with electrothermal atomization (ETA) [9,10] in order to enhance the analyte signal. Tungsten and its compounds also can be used as a permanent modifier to minimize the interaction between the analyte and the carbon component of the furnace.…”

Section: 422mentioning

confidence: 99%

Tungsten-assisted modification of graphite furnaces for an atomic absorption spectrometer

et al. 2009

View full text Add to dashboard Cite

543.422We have used scanning electron microscopy to study changes in the morphology of the inner surface of graphite tube furnaces for an atomic absorption spectrometer when modified by tungsten. We have demonstrated the role of the tungsten-containing material as a dividing interlayer between the sample to be dispensed and the carbon component of the furnace. We consider the advantages and disadvantages of furnaces modified by the proposed methods.Introduction. The modifying properties of tungsten [1][2][3][4][5][6][7][8] are often used in atomic absorption spectrometers (AAS) with electrothermal atomization (ETA) [9,10] in order to enhance the analyte signal. Tungsten and its compounds also can be used as a permanent modifier to minimize the interaction between the analyte and the carbon component of the furnace. On the other hand, in analysis of shaping elements such as, for example, silicon [11,12], it is important to passivate this impurity in the carbon material that is complicated to remove. In order to create a barrier difficult to overcome for any sample component, including the analyte, usually a thin layer of the modifier on the surface of the furnace is sufficient.During a study of the parameters for silicon atomization signals from the surface of tungsten-modified graphite tube furnaces for ETA-AAS, considering the result of [13], we hypothesized that the effectiveness of the modification depends on the method used to treat the graphite furnaces with the modifier. Impregnating the furnace with sodium tungstate, other than improving the sensitivity of silicon determination, did not provide appreciable advantages over the standard furnace with a pyrolytic carbon coating. The positive effect of dispensing the sample with sodium tungstate was more pronounced for furnaces uncontaminated by silicon. Lining with tungsten foil improved the sensitivity and selectivity of the measurements, regardless of the presence of the analyte in the furnace material.The goal of this work was to use scanning electron microscopy to study the morphological features of the surface of graphite furnaces for different methods of tungsten-assisted modification.The Experiment. The studies were carried out on a RE ′ MMA-102 (SELMI, Ukraine) scanning electron microscope equipped with wavelength-dispersive and energy-dispersive x-ray spectrometers. The micrographs were obtained in secondary and backscattered electron detection modes with accelerating voltage 20 kV. A feature of backscatter microphotography is that the gray level is determined by the atomic number: the higher the atomic number of the material, the brighter the section of the image [14]. We used new graphite furnaces made by LEG (Kharkov) (average weight, ≈0.9 g [15]), analogous to a Perkin Elmer HGA-500 furnace (length 28 mm, inner and outer diameters 6 mm and 7.6 mm), for an A-5 atomizer (KAS-120.1 system [16]) made from MPG-6 graphite, and also old furnaces from the same manufacturer with average weight ≈0.8 g.The furnaces were modified by three methods [13]: by imp...

show abstract

“…These are conventional modifiers, which are added each time along with the sample while permanent modifiers are coated once in the beginning of the experiment. Its use is described in several review articles [12][13][14][15]. Usually, carbide forming elements (W, Zr, Nb, Mo and Ta) [16,17], pre-reduced noble metals (Pd, Rh, Ru, Pt and Ir) [18][19][20][21] and mixed carbide forming elements (W and Zr) in combination with noble metals (Rh, Ru or Ir) have been used for coating of the graphite tubes /platforms [22][23][24][25][26][27][28][29][30][31] for determination of hydride forming elements [22][23][24], trace elements in slurries [25][26][27] lubricating oil [28], and naphtha [29].…”

Section: Introductionmentioning

confidence: 99%

Studies on reduction of chloride matrix interferences on determination of germanium using zirconium–ruthenium and palladium–magnesium modifiers by electrothermal atomic absorption spectrometry

Meeravali

Reddy

Kumar

2007

Spectrochimica Acta Part B: Atomic Spectroscopy

View full text Add to dashboard Cite

Graphite atomizers modified with high-melting carbides for electrothermal atomic absorption spectrometry. II. Practical aspects

Cited by 59 publications

References 233 publications

Slurry sampling for the determination of thallium in soils and sediments by graphite furnace atomic absorption spectrometry

Slurry sampling for the determination of thallium in soils and sediments by graphite furnace atomic absorption spectrometry

Tungsten-assisted modification of graphite furnaces for an atomic absorption spectrometer

Studies on reduction of chloride matrix interferences on determination of germanium using zirconium–ruthenium and palladium–magnesium modifiers by electrothermal atomic absorption spectrometry

Contact Info

Product

Resources

About