| Texto completo | |
| Autor(es): |
Silva, Sidnei G.
[1]
;
Donati, George L.
[2]
;
Santos, Luana N.
[1]
;
Jones, Bradley T.
[2]
;
Nobrega, Joaquim A.
[1]
Número total de Autores: 5
|
| Afiliação do(s) autor(es): | [1] Univ Fed Sao Carlos, Dept Chem, Grp Appl Instrumental Anal, BR-13560970 Sao Carlos, SP - Brazil
[2] Wake Forest Univ, Dept Chem, Winston Salem, NC 27109 - USA
Número total de Afiliações: 2
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Analytica Chimica Acta; v. 780, p. 7-12, MAY 30 2013. |
| Citações Web of Science: | 5 |
| Resumo | |
Cobalt is used as chemical modifier to improve sensitivity and minimize matrix effects in Cr determinations by tungsten coil atomic emission spectrometry (WCAES). The atomizer is a tungsten filament extracted from microscope light bulbs. A solid-state power supply and a handheld CCD-based spectrometer are also used in the instrumental setup. In the presence of 1000 mg L-1 Co, WCAES limit of detection for Cr (lambda=425.4 nm) is calculated as 0.070 mg L-1; a 10-fold improvement compared to determinations without Co modifier. The mechanism involved in such signal enhancement is similar to the one observed in ICP OES and ICP-MS determinations of As and Se in the presence of C. Cobalt increases the population of Cr+ by charge transfer reactions. In a second step, Cr+/e(-) recombination takes place, which results in a larger population of excited-state Cr atoms. This alternative excitation route is energetically more efficient than heat transfer from atomizer and gas phase to analyte atoms. A linear dynamic range of 0.25-10 mg L-1 and repeatability of 3.8% (RSD, n = 10) for a 2.0 mg L-1 Cr solution are obtained with this strategy. The modifier high concentration also contributes to improving accuracy due to a matrix-matching effect. The method was applied to a certified reference material of Dogfish Muscle (DORM-2) and no statistically significant difference was observed between determined and certified Cr values at a 95% confidence level. Spike experiments with bottled water samples resulted in recoveries between 93% and 112%. (C) 2013 Elsevier B.V. All rights reserved. (AU) | |
| Processo FAPESP: | 10/50238-5 - Determinacao de fosforo, enxofre e silicio em biodiesel usando espectrometro de massa acoplado ao plasma induzido com interface de colisao e reacao |
| Beneficiário: | George Luis Donati |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 11/13288-7 - Desenvolvimento de sistemas de vaporização e atomização empregando radiação no infravermelho e filamento de tungstênio |
| Beneficiário: | Sidnei Gonçalves da Silva |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |
| Processo FAPESP: | 07/51448-0 - Construcao e aplicacao analitica de espectrometro de emissao atomica com atomizacao eletrotermica em filamento de tungstenio. |
| Beneficiário: | Joaquim de Araújo Nóbrega |
| Modalidade de apoio: | Auxílio à Pesquisa - Regular |