SERS, analytical method

Hernandez-Jover et al. (72) derived an improved analytical method from the HPLC procedure setup they developed in 1995 (73) for the determination of BAs in fish. The method consists of the extensive extraction with HC104, ion-pair (with sodium octanesulfonate) RP-HPLC separation, postcolumn derivatization with PA/ME, and spectrofluorimetric detection. Determination limits were up to 1.5 mg/kg. In particular, His, Tyr, Phe, Ser (serotonine), Cre (creatinine), Try, Oct (octopamine), Dop (dopamine), Cad, Put, Agm (agmatine), Spm, and Spd were studied in pork and beef meat, fresh, cooked, or ripened. Tyramine, His, Put, Cad, and Try levels were... 

Alternatively, various analytical methods based on SPR phenomenon have been developed, including surface plasmon field-enhanced Raman scattering (SERS) [7], surface plasmon field-enhanced fluorescence spectroscopy (SPFS) [8-11], surface enhanced second harmonic generation (SHG) [12], surface enhanced infrared absorption (SEIRA) [13], surface plasmon field-enhanced diffraction spectroscopy (SPDS) [14-18], Most of these methods take advantage of the greatly enhanced electromagnetic field of surface plasmon waves, in order to excite a chromophoric molecule, e.g., a Raman molecule or a fluorescent dye. Therefore, a better sensitivity is expected. 

Hurd, D. C. and Theyer, F. Changes in the physical and chemical properties of biogenic silica from the central equatorial Pacific-- . Solubility, specific surface area, and solution rate constants of acid-cleaned samples, 211 230, in COLbb, Jr., T. R. P., editor) "Analytical Methods in Oceanography," Adv. Chem. Ser. 147, 1975. 

Ut. Free. Natl. Acad. Sci. USA 93,12637 (1996). gen. ACS Symp. Ser. 340,1-310 (1987) Barton-Nakanishi 3, 529-598 (review) Fengel Wegener, Wood Cbemistiy, Ultrastructure, Reactions, Berlin de Gruyter 1989 Kennedy et al.. Cellulose and its Derivatives, Chichester Norwood 1985 Kirk-Othmer(4.)5,476-497 6,1023 7,292 8,451 Klemm et al. (eds.). Comprehensive Cellulose Chemistry (2 Vol. Vol. 1 Fundamentals and Analytical Methods Vol. 2 Derivat-ization of Cellulose), Weinheim Wiley-VCH 1998 Methods Biotechnol. 10,57 -69 (1999) (enzymatic synthesis) Nature (London) 311, 165 (1984) (biosynthesis) Nevell et al.. Cellulose Chemistry, Chichester Norwood 1985 "Tappi J. 72 (3), 169 (1989) Ullmann (5.) AS, 377-418 Wilke et al., Chem. Technol. Rev. 218 Enzymatic Nydrolysis of Cellulose, Park Ridge Noyes Data Corp. 1983 Wood, Methods Enzymol. 160/A, San Diego Academic Press 1988 Young etal.. Cellulose, New York Wiley 1986. - Journal Cellulose (Roberts, ed.), London Chapman Hall (since 1994). - [HS 391211.391290 CAS9004-34-6(C.) 528-50-7(cellobiose)]... 

Abstract Surface analyses have been one of the key technologies for corrosion control and surface finishing. It is very important that the most appropriate apparatus for the purpose of the analyses should be selected from various analytical techniques. In this chapter, surface analytical methods for corrosion control and surface finishing, such as X-ray fluorescence analysis (XRF), X-ray diffraction analysis (XRD), X-ray photo-electron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Auger electron spectroscopy (AES), Secondary ion mass spectrometry (SIMS), Rutherford back-scattering spectrometry (RBS), Surface-enhanced Raman spectroscopy (SERS), Fourier-transform infrared spectroscopy (FTIR), and so on, are briefly introduced. 

Capar S., 1991. Analytical method aspects of assessing dietary intake of trace elements. In Subramanian, K., Iyengar, G., Okamoto, K. (Eds.), Biological Trace Element Research. ACS Symp. Ser. 445, 181-195. 

The discovery and understanding of SERS was important not only because it made Raman a more viable analytical method but also because it introduced the concept of surface-enhanced spectroscopies in general. With the SERS precedent, surface-enhanced resonance Raman spectroscopy (SERRS) and surface-enhanced hyper-Raman spectroscopy (SEHRS) have both been discovered and put to use as analytical tools. In fact, enhancement factors as large as 10 have been measured in SEHRS experiments (see Section VII.B). This immense enhancement was only recently surpassed by the 10 " enhancement measured in single molecule SERS (see Section X). 

SERS has also been applied as a sensitive, molecule-specific detection method in chromatography, e.g. thin layer, liquid, and gas chromatography. SERS-active colloids were deposited on the thin layer plates or mixed continuously with the liquid mobile phases. After adsorption of the analytes, characteristic spectra of the fractions were obtained and enabled unambiguous identification of very small amounts of substance. 

Since SERS and SERRS are substance specific, they are ideal for characterisation and identification of chromatographically separated compounds. SE(R)R is not, unfortunately, as generally applicable as MS or FUR, because the method requires silver sol adsorption, which is strongly analyte-dependent. SE(R)R should, moreover, be considered as a qualitative rather than a quantitative technique, because the absolute activity of the silver sol is batch dependent and the signal intensity within a TLC spot is inhomogeneously distributed. TLC-FTIR and TLC-RS are considered to be more generally applicable methods, but much less sensitive than TLC-FT-SERS FT-Raman offers p,m resolution levels, as compared to about 10p,m for FTIR. TLC-Raman has been reviewed [721],... 

Since its observation more than three decades ago by VanDuyne and Jeanmaire as well as Albrecht and Creighton [23, 24], SERS has been gaining popularity in analytical and physical chemistry and very recently also in the biomedical field [25-28]. The potential of SERS in bioanalytics lie in the combination of sensitivity that can be achieved [29-31] with the structural information that is generated in Raman spectroscopy as a vibrational method. In addition to the increased sensitivity, SERS offers the opportunity... 

Sampling in surface-enhanced Raman and infrared spectroscopy is intimately linked to the optical enhancement induced by arrays and fractals of hot metal particles, primarily of silver and gold. The key to both techniques is preparation of the metal particles either in a suspension or as architectures on the surface of substrates. We will therefore detail the preparation and self-assembly methods used to obtain films, sols, and arrayed architectures coupled with the methods of adsorbing the species of interest on them to obtain optimal enhancement of the Raman and infrared signatures. Surface-enhanced Raman spectroscopy (SERS) has been more widely used and studied because of the relative ease of the sampling process and the ready availability of lasers in the visible range of the optical spectrum. Surface-enhanced infrared spectroscopy (SEIRA) using attenuated total reflection coupled to Fourier transform infrared spectroscopy, on the other hand, is an attractive alternative to SERS but has yet to be widely applied in analytical chemistry. 

A combination of electrochemical methods and SERS is used to detect chlorinated hydrocarbons in aqueous solutions [28], Electrochemistry prepares the surface of a copper electrode for SERS and concomitantly concentrates the analyte on the surface of the electrode, possibly by electrophoretic processes. Detection sensitivity of <1 ppm for trichloroethylene, for example, was achieved. 

The SERS spectra from an organic analyte deposited on the substrate were found to show a enhancement factor of 104, which is comparable to the enhancement obtained from two-dimensional silver gratings produced by electron beam lithography by Kahl et al. [39]. Like the self-assembled three-dimensional opal gratings, the templated gratings provide clear practical advantages over ordered substrates produced by more complex and expensive methods. The results reported are summarized in Table 10.2. From the... 

The shape of the metal specimen considered is obviously related to the kind of system to be modelled. For SERS and the others SE phenomena, the presence of curved surfaces, with a curvature radius on the nanometric scale, is fundamental for the enhancement. Thus, spheres, ellipsoids, ensembles of spheres, spheres close to planar metal surfaces and planar metal surfaces with random roughness have been considered. We refer to the review by Metiu [57], which describes most of these analytically solvable models. More recently, the modelling of the electric field acting on the point molecule has moved to more realistic shapes (including fractal metal specimen) [59] which require numerical methods to be tackled. The aim of these approaches is usually to calculate the total electric field around the metal particle, and the molecule does not even appear explicitly in the calculations. Interested readers are referred to some recent reviews on the subject [60] (see also Chapters 2 and 5 of ref. [56]). 

To demonstrate the application of these butterfly wing SERS substrates to the problem of protein-binding detection, Garrett et al. devised a protein-binding assay. There are a variety of methods for binding proteins to a metal surface, some of which depend on the amino acid composition of the protein, others of which do not. Direct adsorption via covalent bonds between sulfur groups in proteins and metal surfaces has been used with some success [43] however, this method is unsuitable for use in Raman spectroscopy-based assays, as nonspecific binding may result in a wide variety of conformational orientations of the molecules with respect to the metal s surface. This can lead to Raman spectra that are difficult to reproduce. Not only that, but the analyte may bind to the metal as well as the antibody, which can lead to noisy spectra. 

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