Chemical reactions in the graphite tube for some carbide and oxide forming elements

Wendl, W.; Müller‐Vogt, G.

doi:10.1016/0584-8547(84)80031-2

Cited by 63 publications

(18 citation statements)

References 7 publications

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“…Thermal decomposition of the carbide 24 or vaporization of the free metal 25 has been proposed as atomization mechanisms for chromium in GF AAS. However, these proposed mechanisms do not explain the behavior observed in the present work.…”

Section: Heating Program Optimization For Cr(vi) Speciationmentioning

confidence: 99%

In vitro Cr(VI) speciation in synthetic saliva after releasing from orthodontic brackets using silica-aptes separation and GF AAS determination

et al. 2016

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A method for Cr(VI) speciation in synthetic saliva after releasing from orthodontic brackets, using silica nanoparticles organofunctionalized with (3-aminopropyl)triethoxysilane (APTES) for Cr(III)/Cr(VI) separation and GF AAS determination is proposed. Under the optimized conditions, Cr(VI) speciation was performed using 150 mg of silica organofunctionalized with 2.0% (v v -1 ) of APTES at pH 8. It was observed different sensitivity when calibrations of GF AAS were performed using Cr(III) or Cr(VI) as standard solutions. Consequently, calibrations using stoichiometric mixtures (Cr(III) + Cr(VI)) were used for total Cr determination and calibration using Cr(VI) was used only for the determination of this specie. The reliability of the proposed silica-APTES separation procedure and GF AAS determination was checked by addition of both species in synthetic saliva. Recoveries ranging from 97 to 110% were obtained. The repeatability, based on the relative standard deviation (RSD) inter days was less than 6%. A corrosion test was carried out on 20 orthodontic brackets from two different models, after immersion in synthetic saliva (pH=6.0) at 37 °C with agitation (125 rpm) for 24 h. It was observed that about 40% of the total chromium released from the analyzed orthodontic brackets was Cr(VI).

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Section: Heating Program Optimization For Cr(vi) Speciationmentioning

confidence: 99%

In vitro Cr(VI) speciation in synthetic saliva after releasing from orthodontic brackets using silica-aptes separation and GF AAS determination

et al. 2016

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“…Vanadium is a refractory metal with a melting point of 1730 1C and a boiling point of 3000 1C. In the graphite furnace it is present in the form of carbides or oxides, so that normally relatively high pyrolysis temperatures can be applied [37][38][39][40][41]. The higher oxides can be reduced to lower oxides and carbides or dissociated.…”

Section: Introductionmentioning

confidence: 99%

“…The higher oxides can be reduced to lower oxides and carbides or dissociated. For example, VO and VO 2 were detected in the gas phase by mass spectrometry [40] and X-ray diffraction experiments indicated only the presence of VC above 1200 1C [37]. The V compounds formed in a graphite furnace are not particularly stable, so that V can be determined relatively easily by GF AAS [41].…”

Section: Introductionmentioning

confidence: 99%

“…The V compounds formed in a graphite furnace are not particularly stable, so that V can be determined relatively easily by GF AAS [41]. The V atomization can be a thermal decomposition of the solid VC carbide [37,38], a thermal decomposition of VO (g) [39], or a sublimation of V from the solid phase [41,42]. Fast furnace heating, good pyrolytic coating and high atomization temperature are recommended for the atomization of V [41,43].…”

Section: Introductionmentioning

confidence: 99%

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Effect of magnesium acetylacetonate on the signal of organic forms of vanadium in graphite furnace atomic absorption spectrometry

Kowalewska

Welz

Castilho

et al. 2013

Talanta

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The aim of this work was to investigate the influence of magnesium acetylacetonate (MgA) on the signal of organic forms of vanadium in xylene solution by graphite furnace atomic absorption spectrometry. MgA alone or mixed with palladium acetylacetonate (PdA) was considered as a chemical modifier. It has been found that MgA does not improve, but decreases significantly the integrated absorbance of V in the form of alkyl-aryl sulfonates, acetylacetonates, porphyrins and in lubricating oils, while its effect is negligible in the case of "dark products" from petroleum distillation, i.e., heavy oil fractions and residues. The decrease is also observed in the presence of Pd. The MgA (or MgA+PdA) effect on the integrated absorbance of V has been studied using the following variants: different ways of modifier application, various pyrolysis temperature, additional application of air ashing, preliminary pretreatment with iodine and methyltrioctylammonium chloride, application of various graphite furnace heating systems (longitudinal or transverse) and various optical and background correction systems (medium-resolution line source spectrometer with deuterium background correction or high-resolution continuum source spectrometer). The experiments indicate formation of more refractory compounds as a possible reason for the decrease of the integrated absorbance for some forms of V in the presence of MgA. The application of MgA as a chemical modifier in V determination is not recommended. Results of this work have general importance as, apart from the intentional use of MgA as a modifier, organic Mg compounds, present in petroleum products for other reason (e.g. as an additive), can influence the signal of V compounds and hence the accuracy in V determination. Generally, petroleum products with known amount of V are recommended as standards; however, lubricating oils can be inadequate for "dark products" from petroleum distillation. In the case of unknown samples it is recommended to check the effect of Mg using recovery tests of V in a form that is affected by MgA.

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“…The oxide or carbide of tin is more resistant to volatilization loss, and has been reported to give a higher sensitivity of tin than chloride. 5 The authors, on the other hand, have reported that the sensitivity for organotin can be increased by the addition of organopalladium as a matrix modifier in an organic solvent and by employing a longer ashing time.6 As is widely known, organotin is highly volatile and tin is determined only with very poor sensitivity.' The sensitivity is so poor that it is practically useless for real samples.…”

mentioning

confidence: 99%

Effect of Oxygen Atoms in the Solvent and Ligand in Graphite-Furnace Atomic Absorption Spectrometry of Organotin and Inorganic Tin with the Use of an Organopalladium Matrix Modifier

Gong

Ochiai

et al. 1993

ANAL. SCI.

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Chemical reactions in the graphite tube for some carbide and oxide forming elements

Cited by 63 publications

References 7 publications

In vitro Cr(VI) speciation in synthetic saliva after releasing from orthodontic brackets using silica-aptes separation and GF AAS determination

In vitro Cr(VI) speciation in synthetic saliva after releasing from orthodontic brackets using silica-aptes separation and GF AAS determination

Effect of magnesium acetylacetonate on the signal of organic forms of vanadium in graphite furnace atomic absorption spectrometry

Effect of Oxygen Atoms in the Solvent and Ligand in Graphite-Furnace Atomic Absorption Spectrometry of Organotin and Inorganic Tin with the Use of an Organopalladium Matrix Modifier

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