Detection fluorescence spectroscopy

Keywords. Enzymes, Mass spectrometry, IR-thermography, Optical detection. Fluorescence spectroscopy... 

A.L. Golub, E.F. Gudgin Dickson, J.C. Kennedy, S.L. Marcus, Y. Park, R.H. Pottier (1999). The monitoring of ALA-induced protoporphyrin IX accumulation and clearance in patients with skin lesions by in vivo surface-detected fluorescence spectroscopy. Lasers Med. Sci., 14, 112-122. 

Ambrose W P, Basche T and Moerner W E 1991 Detection and spectroscopy of single pentacene molecules in a p-terphenyl crystal by means of fluorescence excitation J. Phys. Chem 95 7150-63... 

Electron Microprobe A.na.Iysis, Electron microprobe analysis (ema) is a technique based on x-ray fluorescence from atoms in the near-surface region of a material stimulated by a focused beam of high energy electrons (7—9,30). Essentially, this method is based on electron-induced x-ray emission as opposed to x-ray-induced x-ray emission, which forms the basis of conventional x-ray fluorescence (xrf) spectroscopy (31). The microprobe form of this x-ray fluorescence spectroscopy was first developed by Castaing in 1951 (32), and today is a mature technique. Primary beam electrons with energies of 10—30 keV are used and sample the material to a depth on the order of 1 pm. X-rays from all elements with the exception of H, He, and Li can be detected. 

The continuous methods combine sample collection and the measurement technique in one automated process. The measurement methods used for continuous analyzers include conductometric, colorimetric, coulometric, and amperometric techniques for the determination of SO2 collected in a liquid medium (7). Other continuous methods utilize physicochemical techniques for detection of SO2 in a gas stream. These include flame photometric detection (described earlier) and fluorescence spectroscopy (8). Instruments based on all of these principles are available which meet standard performance specifications. 

The most significant differences (i.e. independence) in the analytical methods are provided in the final chromatographic separation and detection step using GC/ MS and LC-FL. GC and reversed-phase LG provide significantly different separation mechanisms for PAHs and thus provide the independence required in the separation. The use of mass spectrometry (MS) for the GC detection and fluorescence spectroscopy for the LG detection provide further independence in the methods, e.g. MS can not differentiate among PAH isomers whereas fluorescence spectroscopy often can. For the GC/MS analyses the 5% phenyl methylpolysiloxane phase has been a commonly used phase for the separation of PAHs however, several important PAH isomers are not completely resolved on this phase, i.e. chrysene and triphenylene, benzo[b]fluoranthene and benzofjjfluoranthene, and diben-z[o,h]anthracene and dibenz[a,c]anthracene. To achieve separation of these isomers, GC/MS analyses were also performed using two other phases with different selectivity, a 50% phenyl methylpolysiloxane phase and a smectic liquid crystalline phase. 

Wolfbeis, O. S. Fiierlinger, E. pH-dependent fluorescence spectroscopy. 15. Detection of an unusual excited-state species of 3-hydroxyxanthone. J. Am. Chem. Soc. 1982, 104, 4069 1072. 

Instrumentation for fluorescence spectroscopy has been reviewed [8]. For standards in fluorescence spectroscopy, see Miller [138]. Fluorescence detection in HPLC has recently been reviewed [137], Phosphorescence detection of polymer/additive extracts is not being practised. 

Raman spectroscopy has enjoyed a dramatic improvement during the last few years the interference by fluorescence of impurities is virtually eliminated. Up-to-date near-infrared Raman spectrometers now meet most demands for a modern analytical instrument concerning applicability, analytical information and convenience. In spite of its potential abilities, Raman spectroscopy has until recently not been extensively used for real-life polymer/additive-related problem solving, but does hold promise. Resonance Raman spectroscopy exhibits very high selectivity. Further improvements in spectropho-tometric measurement detection limits are also closely related to advances in laser technology. Apart from Raman spectroscopy, areas in which the laser is proving indispensable include molecular and fluorescence spectroscopy. The major use of lasers in analytical atomic... 

The general principle of detection of free radicals is based on the spectroscopy (absorption and emission) and mass spectrometry (ionization) or combination of both. An early review has summarized various techniques to detect small free radicals, particularly diatomic and triatomic species.68 Essentially, the spectroscopy of free radicals provides basic knowledge for the detection of radicals, and the spectroscopy of numerous free radicals has been well characterized (see recent reviews2-4). Two experimental techniques are most popular for spectroscopy studies and thus for detection of radicals laser-induced fluorescence (LIF) and resonance-enhanced multiphoton ionization (REMPI). In the photochemistry studies of free radicals, the intense, tunable and narrow-bandwidth lasers are essential for both the detection (via spectroscopy and photoionization) and the photodissociation of free radicals. 

FBAs can also be estimated quantitatively by fluorescence spectroscopy, which is much more sensitive than the ultraviolet method but tends to be prone to error and is less convenient to use. Small quantities of impurities may lead to serious distortions of both emission and excitation spectra. Indeed, a comparison of ultraviolet absorption and fluorescence excitation spectra can yield useful information on the purity of an FBA. Different samples of an analytically pure FBA will show identical absorption and excitation spectra. Nevertheless, an on-line fluorescence spectroscopic method of analysis has been developed for the quantitative estimation of FBAs and other fluorescent additives present on a textile substrate. The procedure was demonstrated by measuring the fluorescence intensity at various excitation wavelengths of moving nylon woven fabrics treated with various concentrations of an FBA and an anionic sizing agent. It is possible to detect remarkably small differences in concentrations of the absorbed materials present [67]. 

Lindgren M, Sorgjerd K, Hammarstrom P (2005) Detection and characterization of aggregates, prefibrillar amyloidogenic oligomers, and protofibrils using fluorescence spectroscopy. Biophys J 88(6) 4200-4212... 

Buehler, C., Stoeckli, K. and Auer, M. (2001). The integration of single molecule detection technologies into miniturized drug screening Current status and future perspectives. In New Trends in Fluorescence Spectroscopy (Valeur, B. and Brochon, J. C., eds.). Springer, Berlin, pp. 331-79. 

Conventional TCSPC equipment has been successfully employed in LSM for fluorescence spectroscopy on discrete microscopic volumes [18, 19] and for fluorescence lifetime imaging at a low acquisition speed [1], The use of conventional TCSPC equipment for imaging results in very long acquisition times, several to many minutes per (time-resolved) image. Importantly, operating the TCSPC detection system at too high detection rates, above 5% of the excitation frequency, results in distortion of the recorded decay curve [20],... 

Volkmer, A., Hatrick, D. A. and Birch, D. J. S. (1997). Time-resolved nonlinear fluorescence spectroscopy using femtosecond multiphoton excitation and single-photon timing detection. Meas. Sci. Technol. 8, 1339 19. 

Chong et al. [742] have described a multielement analysis of multicomponent metallic electrode deposits, based on scanning electron microscopy with energy dispersive X-ray fluorescence detection, followed by dissolution and ICP-MS detection. Application of the method is described for determination of trace elements in seawater, including the above elements. These elements are simultaneously electrodeposited onto a niobium-wire working electrode at -1.40 V relative to an Ag/AgCl reference electrode, and subjected to energy dispersive X-ray fluorescence spectroscopy analysis. Internal standardisation... 

Most commonly absorption or fluorescence spectroscopy is used for detection of the changes in the concentration of G or HG. The monitoring wavelength is chosen so that the difference between the molar absorptivities, in case of absorption, or emission quantum yields, in the case of fluorescence detection, between G and HG is maximized. The amplitude of the relaxation process depends on the difference in the molar absorptivities or fluorescence quantum yields, but the observed rate constants are the same at all observation wavelengths when the kinetics are first- or pseudo-first order (Fig. 3). 

Bublitz [62] used time resolved laser induced fluorescence spectroscopy and fibre optics to determine polyaromatic hydrocarbons in oil polluted soils. The detection limit was 5mg kgy1 oil in soil. 

Rabaioli G., Taglietti A. (2001) Fluorometric Detection of Anion Activity and Temperature Changes, in Valeur B. and Brochon J. C. (Eds), New Trends in Fluorescence Spectroscopy. Applications to Chemical and Life Sciences, Springer-Verlag, Berlin, pp. 209-27. 

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