Fluorescence quantitative relationship

In a report by Thoma and Kerker (95), the effects of irradiation time and absolute radiation dose on the decomposition rates and photoproducts of betametha-zone valerate chloramphenicol, molsidomine, metronidazole, and indomethacin were studied. Their results show that substances sensitive to UV radiation, such as the above-listed five drugs, despite their instability in sunlight, have little or no decomposition upon exposure to irradiation from tubular fluorescent lamps at an irradiation intensity of 79 W/m. In addition, for those compounds that did degrade, they noted differences in the quantitative relationships of the decomposition products as well as their decomposition rates. The tubular fluorescent lamps used were found to be unsuitable for simulation of direct daylight. 

Luminescence spectroscopy is used more often in quantitative analysis than in any other application. The quantitative relationship between fluorescence intensity F and analyte concentration C is derived from the Beer-Lambert law ... 

The quantitative relationship between fluorescence power and analyte concentration can be derived from the number of molecules in the excited state and the radiant power absorbed by the processed sample ... 

A maximum cellular content of carotenoids could be estimated since there was a quantitative relationship between total carotenoid content and average fluorescence intensity of a culture. A maximum yield of between 14,600 and 19,(XX) jig g was obtained. However, there was considerable heterogenity in autofluorescence among individual cells which suggests that the yield could be improved. Maximum synthesis could also be improved by directed transport, esterification of astaxanthin, or excretion as described below. 

Chemicals listed in Table I have been tested for their effects on chlorophyll fluorescence. All chemicals show prompt fluorescence kinetics similar to that of DCMU, except for nitrofen and trifluralin which are excluded from the group of so-called DCMU-type inhibitors . A quantitative relationship between inhibitor concentration and selected fluorescence parameters has been researched. 

Fluorescence analysis methods are now widely used because of their extreme sensitivity, which provides detection limits at picomolar levels and below, and the great variety of sample presentation methods available. Flowing liquids, soHd surfaces, concentrated solutions, and suspensions can all be studied in addition to measurements in dilute solution. This article is concerned with the quantitative relationships underpinning steady-state fluorescence measurements time resolved fluorescence is considered separately. 

Hence, it is possible to construct a standard curve relating viscometric measurements to steady-state anisotropy measurements for a particular fluid and use the quantitative relationship to determine the viscosity of the fluid by fluorescence polarization [4,9-11]. A standard curve in a reference calibration oil such as white paraffin oil can be used to determine the viscosity of another fluid as long as the calibration fluid is similar in dielectric constant and viscosity to the fluid being analyzed. It is important to keep in mind that the same fluorescent probe may display different behavior even in different hydrocarbon calibration oils, hence one must exercise caution when determining absolute values for microvis-... 

The relationships between amount of substance applied and the heights or areas of the peaks in the chromatogram scan are employed for the quantitative determination of fluorescent substances The following relationship is apphcable when the amount of substance is small... 

Both WDXRF and EDXRF lend themselves admirably to quantitative analysis, since there is a relationship between the wavelength or energy of a characteristic X-ray photon and the atomic number of the element from which the characteristic emission line occurs. The fluorescence intensity of a given element is proportional to the weight fraction. Emitted fluorescence radiation is partly absorbed by the matrix, depending on the total mass absorption coefficient ... 

One of the most popular applications of molecular rotors is the quantitative determination of solvent viscosity (for some examples, see references [18, 23-27] and Sect. 5). Viscosity refers to a bulk property, but molecular rotors change their behavior under the influence of the solvent on the molecular scale. Most commonly, the diffusivity of a fluorophore is related to bulk viscosity through the Debye-Stokes-Einstein relationship where the diffusion constant D is inversely proportional to bulk viscosity rj. Established techniques such as fluorescent recovery after photobleaching (FRAP) and fluorescence anisotropy build on the diffusivity of a fluorophore. However, the relationship between diffusivity on a molecular scale and bulk viscosity is always an approximation, because it does not consider molecular-scale effects such as size differences between fluorophore and solvent, electrostatic interactions, hydrogen bond formation, or a possible anisotropy of the environment. Nonetheless, approaches exist to resolve this conflict between bulk viscosity and apparent microviscosity at the molecular scale. Forster and Hoffmann examined some triphenylamine dyes with TICT characteristics. These dyes are characterized by radiationless relaxation from the TICT state. Forster and Hoffmann found a power-law relationship between quantum yield and solvent viscosity both analytically and experimentally [28]. For a quantitative derivation of the power-law relationship, Forster and Hoffmann define the solvent s microfriction k by applying the Debye-Stokes-Einstein diffusion model (2)... 

Numerous theoretical and experimental studies of solvent effects on the fluorescence spectra of organic molecules (fluorophores) have led to a variety of quantitative expressions similar to Eq. (6-2) [4, 13, 16, 90, 112, 487]. Among the existing relationships describing how a change in dipole moment (A// = — fif) correlates with elec-... 

Thanks to the linear relationship between the intensity of the characteristic X-ray radiation generated in the sample by electrons and the concentration of the given element, quantitative elemental analysis is also possible. X-ray microanalysis performed using SEM-EDX is, in principle, point analysis and is suitable for studying very small samples of solid materials that are stable in an electron beam. The X-ray fluorescence method, on the other hand, can be applied to the study of both solids and liquids. The signal reaching the detector always originates from a certain sample volume, and thus it is not point analysis. It is more sensitive than the SEM-EDX method. 

Barnett JD, Block S, Piermarini GJ (1973) An optical fluorescence system for quantitative pressure measurement in the diamond-anvil cell. Rev Sci Instrum 44 1-9 Batlogg B, Maines RG, Greenblatt M, DiGregorio S (1984) Novel p-V relationship in ReOs under pressure. Phys Rev B 29 3762-3764... 

When the fluorescence method becomes more generally adopted, it will be necessary to study not only those factors (neutral salt, temperature) which alter the equilibrium relationships, but also those which influence fluorescence (deformation effect, influence of solvent, etc. cf. P. W. Danckwortt, Luminescence Analysis, 2 Ed., Leipzig 1929 F. Weigebt, Optical Methods in Chemistry, 1927). The interesting publication of L. J. Desha should be consulted regarding the quantitative aspects of fluorometry. In quantitative work it is best to use the filtered monochromatic ultraviolet radiation (X = 366 mm) from a quartz lamp. Con-... 

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