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

TALANTA

卷:103

Article

Kowalewska, Zofia¹  Welz, Bernhard^2,3  Castilho, Ivan N. B.²  Carasek, Eduardo² 

[1] Res Dev Ctr Refinery Ind SA, PL-09411 Plock, Poland

[2] Univ Fed Santa Catarina, Dept Quim, BR-88040900 Florianopolis, SC, Brazil

[3] Univ Fed Bahia, Inst Nacl Ciencia & Tecnol, CNPq, INCT Energia & Ambiente, Salvador, BA, Brazil

关键词: Vanadium determination;    GF AAS;    HR-CS GF AAS;    Chemical modifiers;    Petroleum analysis;   

DOI  :  10.1016/j.talanta.2012.10.007

来源: Elsevier

【 摘 要 】

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. (C) 2012 Elsevier B.V. All rights reserved.

【 授权许可】

Free