Monitoring methods Fluorescence

In addition, typical methods of sensing are total internal reflection fluorescence or monitoring of fluorescence resonance energy transfer6,7. The second class is a direct optical detection principle which relies either on reflectometry or refractometry. The latter is connected to evanescent field... 

Signals for methyl paraben were monitored with UV detection at 254 nm. The signal for rhodamine 110 chloride was monitored via fluorescence detection with an excitation filter of 482 nm (35 nm bandwidth) and emission filter of 535 nm (40 nm bandwidth). A gradient method (same as the one in Figure 6.16) was used. The compositions of mobile phases A and B were 5 95 H20 CH3CN with 0.1 HCOOH and CH3CN with 0.085% HCOOH, respectively, with a total flow rate of 300 fiL/ min (corresponding to 12.5 /rL/min for each column). 

Continuous monitoring methods based on amperometric (Nikolic et al. 1992) or spectrophotometric (Kuban 1992 Ma and Liu 1992) techniques for the quantification of free cyanide are also available. Ion chromatography with amperometric determination provides good sensitivity (2 ppb) and selectivity for free cyanide and the weak complexes of cadmium and zinc (Rocklin and Johnson 1983). Postcolumn derivatization and fluorescence detection provides low detection limits as well (0.1 ppb) (Gamoh and Imamichi 1991). 

Automatic on-line monitoring of inhibitor reserve. This involves sampling a bypass stream of cooling water and is usually achieved by the measurement of a specific chemical inhibitor component, such as molybdenum. Other monitoring methods include azole fluorescence (as in the well-established Nalco TRASAR system) or... 

The triplet-photochrome labeling method has been used to study very rare encounters in a system containing the Erythrosin B sensitiser and SITC photochrome probe (Mekler and Likhtenshtein, 1986). Both types of the molecules were covalently bound to a-chymotrypsin. The photoisomerisation kinetics was monitored by fluorescence decay of the frans-SITS. The rate constants of the triplet-triplet energy transfer between Erythrosin B and SITS (at room temperature and pH 7) were found k,r = 2 xlO7 NT s-1 and ktT = 107 M V. It should be emphasized that the concentration of the triplet sensitiser attached to the protein did not exceed 10 7 M in those experiments, and the collision frequencies were close to 10 s 1 which are 8-9 orders of magnitude less than those measured with the regular luminescence or ESR techniques. 

Monitoring methods may be classified as direct scanning without subsequent spectral conversion or as additional methcxls such as measutements based upon fluorescence, photo-acoustic spectroscopy, spin resonance, and radioactivity measurements. 

There are numerous spectroscopic studies of the chromophores bound to the chemically modified silica gel(2-4) but dynamic studies such as fluorescence lifetime measurements are rather limited. In their recent work, Lochmuller and Hunnicutt (5) have employed the time-correlated single photon counting technique and analyzed the non-exponential decays in detail to disclose the complex features of the interfaces through (10-(3-pyrenyl)decyl)dimethylmonochlorosilane chemically bonded to silica as a probe. Unfortunately, however, their method, though sophisticated enough to monitor heterogeneous fluorescence decays, cannot distinguish one microparticle from the other and hence unavoidably follows overall decays. 

For the development of methods able to estimate biological effects of radiation, two approaches were pursued in this study. The first approach concerned the utilisation of intact photos3mthetic microorganisms, monitored by fluorescence emission as signal transduction. The second approach utilised extracted and fixwen biological material, also monitored by fluorescence of PSIL For its particular feature, after isolation and suitable inmiobilisation, the multiprotein complex PSII maintained the activity. 

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