Chemical analysis of polycyclic aromatic hydrocarbons by surface-enhanced Raman spectroscopy

Costa, Juliana Leles; Sant’Ana, Antônio Carlos; Cório, Paola; Temperini, Márcia L. A.

doi:10.1016/j.talanta.2006.01.036

Cited by 73 publications

(52 citation statements)

References 18 publications

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Section: Spectroelectrochemistrymentioning

confidence: 99%

“…Recently it has been demonstrated that PAH adsorption on nanostructured gold surfaces may cause their oxidative degradation. 16,17 When the applied potential is made more positive than + 0.9 V, Raman spectral changes indicate the electrochemical oxidation of adsorbed anthracene.New Raman bands, characteristic of oxidized species, are observed at 1032, 1600 and 1665 cm -1 . Changes are also seen in the high frequency region of the spectra, where characteristic vibrational modes of aromatic and aliphatic CH stretching appear.…”

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confidence: 99%

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Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

Cordeiro

Cório

2009

J. Braz. Chem. Soc.

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Este trabalho apresenta o estudo do comportamento fotoquímico de hidrocarbonetos policíclicos aromáticos (HPAs), potenciais poluentes secundários em reações em aerossóis, através de espectroscopia Raman em comparação com seu comportamento eletroquímico. Os HPAs estudados incluem pireno, antraceno, fenantreno e fluoreno. Esses foram adsorvidos sobre o catalisador TiO 2 e irradiados com radiação ultravioleta (254 nm). A oxidação eletroquímica foi estudada via espectroscopia Raman intensificada pela superfície (SERS) in situ e levou à formação de produtos carbonilados. Intermediários oxidados contendo o grupo C=O foram também observados nos processos de fotodegradação. A comparação entre os intermediários formados nos processos fotoquímicos e eletroquímicos revela produtos idênticos para o antraceno, mas não para o pireno. Esse resultado advém da diferença de mecanismo para esses dois processos. A degradação fotocatalítica sobre TiO 2 é iniciada por radicais hidroxila, enquanto a oxidação eletroquímica é iniciada por transferência eletrônica direta com o HPA adsorvido no eletrodo, gerando cátions radicais do HPA que desencadeiam as reações subseqüentes. This paper presents the study of photochemical behavior of polycyclic aromatic hydrocarbons (PAHs), potential pollutants in secondary reactions in aerosols, through Raman spectroscopy compared with its electrochemical behavior. The PAHs studied include pyrene, anthracene, phenanthrene and fluorene. These were adsorbed onto TiO 2 and irradiated with ultraviolet light (254 nm). Their electrochemical oxidation was studied by in situ Surface-enhanced Raman Scattering (SERS) and led to the formation of carbonyl-containing products. Oxidized intermediates bearing the C=O group were also formed during photodegradation. The joint analysis of the photodegradation data with those produced by electrochemical means -using spectroscopic techniques for the identification and characterization of the products -revealed the formation of identical products for anthracene, but not for pyrene. A reasonable explanation for this difference in results is that photochemical and electrochemical oxidation reactions proceed via different mechanisms. While photocatalytic degradation over TiO 2 is initiated by hydroxyl radicals, electrochemical oxidation is initiated by the direct electron transfer from adsorbed PAH to the electrode, generating PAH cation radicals that undergo subsequent reactions.Keywords: advanced oxidative processes, photocatalysis, TiO 2 , spectroelectrochemistry, SERS IntroductionExcessive concentrations of particulate matter in the atmosphere are cause for significant concern in many metropolitan areas around the world. This particulate matter exhibits dynamic behavior owing to potential chemical and photochemical reactions, changing its composition according to time and environment. Polycyclic aromatic hydrocarbons (PAHs), a class of chemicals present in particulate matter, are of special interest due to their mutagenic and carcinogenic properties. 1,2 PAHs are character...

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Section: Spectroelectrochemistrymentioning

confidence: 99%

mentioning

confidence: 99%

Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

Cordeiro

Cório

2009

J. Braz. Chem. Soc.

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“…Hydrophobic forces were proposed as being responsible for chemical sensing between PAHs and an Au-propanethiol modified surface analyzed with Raman spectroscopy. 21 In addition to the hydrophobic forces, the interaction between the Au-HPYT and coronene should take the contribution of electronic nature into consideration. The pyridine moiety in the HPYT molecule has a lone electron pair pointing to solution.…”

Section: Scanning Tunneling Microscopymentioning

confidence: 99%

Polycyclic aromatic hydrocarbons from asphalt binder: extraction and characterization

Pinheiro¹,

Fernandes²,

Cavalcante³

et al. 2009

J. Braz. Chem. Soc.

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“…Attention to this point has focused on simpler chemical modifiers that can introduce a degree of selectivity or promote binding as well as signal attachment through direct observation of additional bands characteristic of the analyte itself. Figure 3.6 shows a selection of the surface-binding modifiers (predominantly thiols) [40][41][42][43][44][45][46][47][48] that have already been used to promote adsorption of specific target analytes for SERS.…”

Section: Selectivitymentioning

confidence: 99%

“…More generally, within mixed monolayers, there is the possibility of varying the properties of the surface between the extreme values found for full monolayer coverage of either component and thus of designing and building surfaces with continuously tuneable properties. Alternatively, the properties of surfaces treated Figure 3.6 Surface-modifying agents that have been used for SERS: (a) dithiocarbamate calix [4]arene derivative [40], (b) pentachlorobenzenethiol [41], (c) N-(9methylanthracene)N -methyldithiocarbamate [40], (d) trimercaptotriazine [42], (e) thiol derivatized dibenzo-18 crown-6 [43], (f) lucigenin [44], (g) paraquat [44], (h) cysteamine derivatives including R = H or CH 3 [45], (i) propane-1-thiol [46], (j) mixed decane-1-thiol and 6-mercaptohexan-1-ol [47] and (k) hexadecane-1-thiol [48].…”

Section: Selectivitymentioning

confidence: 99%

Quantitative SERS Methods

Bell¹,

Stewart²

2010

Surface Enhanced Raman Spectroscopy

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The goal of transforming SERS from an interesting novelty into a viable quantitative analytical technique has been pursued for many years, but it is only recently that the first indications that quantitative SERS could be generally achievable have appeared. Up to this point, the challenges of preparing sensitive and reproducible enhancing media and the need to develop a deep understanding of the fundamental mechanisms of the effect (or at least to have a working knowledge of the relationship between the microstructure of the enhancing materials, their surface chemistry and the enhancements that they provide; see also Chapter 1) have been sufficient to occupy the attention of researchers who were interested in using SERS for quantitative measurements. However, many of these issues have now either been fully resolved or at least brought to the stage where they are no longer impediments. For example, new generations of enhancing media have been developed; the links between microstructure, plasmon resonances and enhancements have been established; and the role of the media's surface chemistry is being addressed. This chapter discusses these new developments and also considers the extent to which the separate strands can be combined to create standard, generally applicable methods for quantitative SERS. In addition, it highlights the need to begin the process of judging the success of new SERS methods against competing technologies, rather than against previous SERS results. SERS MediaThe choice of enhancing media for SERS studies has grown to an extraordinary extent, although they can still be broadly divided into solution-phase suspensions of nanoparticles and micro-textured solid substrates. This division dates back to the earliest work in the area, which used either colloidal suspensions of silver or gold nanoparticles [1] or the surfaces of roughened noble-metal electrodes [2]. Since this

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Chemical analysis of polycyclic aromatic hydrocarbons by surface-enhanced Raman spectroscopy

Cited by 73 publications

References 18 publications

Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

Electrochemical and photocatalytic reactions of polycyclic aromatic hydrocarbons investigated by raman spectroscopy

Polycyclic aromatic hydrocarbons from asphalt binder: extraction and characterization

Quantitative SERS Methods

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