Time-resolved fluorimetry

This time-resolved fluorescence technique allows a measure of the time dependence of fluorescence intensity after a short excitation pulse. It consists of obtaining a spectrum measured within a narrow time window during the decay of the fluorescence of interest. The usefulness of this technique is now well proven for biochemical assays and immunoassays. Lanthanide chelates have luminescence decay times over 600 ps, which allows time-gated fluorecence detection, with a complete rejection of other fluorecence signals. For these quantitative applications, the primary source is generally a quartz lamp associated with a splitter. 

There are several ways to perform time-resolved fluorescence measurements. Since the time dependence of fluorescence emission is typically on a picosecond to nanosecond time scale it is very difficult to achieve. To overcome this difficulty either a frequency domain method or the single photon counting approach is used. 

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Keywords Anisotropy Intensity sensing Time-resolved fluorimetry Wavelength ratiometry... 

Time of flight (TOF), 75 660-661 Time-of-flight (ToF) mass analyzers, 24 109 Time of flight diffraction (TOFD), 79 486 Time-of-flight instrumentation, in particle counting, 78 150—151 Time-of-flight-SIMS technique, 24 109 Time-resolved fluorimetry, 74 148-149 Time-resolved spectra, analysis of, 74 613 Time standards, 75 749—750 Time-temperature parameters (TTP), 73 471, 478, 479 creep properties and, 73 480 Time-temperature superposition, 27 746-747... 

The problem of background fluorescence has been largely overcome with the introduction of time-resolved fluorimetry. This technique relies on the use of fluorophores with a long-lived fluorescence which can be measured... 

R. D. Petrea, M. J. Sepaniak, and T. Vo-Dinh, Fiber-optic time-resolved fluorimetry for immunoassays, Talanta 35, 139-144 (1988). 

The advent of nanosecond time-resolved fluorimetry in the late 1970s and early 1980s made it possible to obtain fluorescence lifetimes of the prototropic forms as a function of proton concentration. Dynamic analysis at nanosecond resolution enabled a more accurate estimation of pK a values. Phenomenon like pro-ton-induced fluorescence quenching in naphthylamines could then be given a satisfactory explanation. Shizuka s review [18] in 1985 summarizes the dynamic analysis techniques that were employed. Certain intermolecular proton-transfer... 

Time-resolved fluorimetry is also useful for the elimination of interferences from stray light caused by Rayleigh and Raman scatter. The latter phenomena occur on a time scale of because they have... 

Time-resolved fluorimetry is also useful for the elimination of interferences from stray light due to Rayleigh and Raman scatter. The latter phenomena occur on a time scale of l(r14-l(T13 s and, as they have a much shorter duration than lamp or laser pulses, the light associated with them can be eliminated from the signal that ultimately reaches the detector. Time-correlated single-photon counting is superior in its ability to resolve multiple fluorescence from the same solution. 

Lytle, F.E., and Kelsey, M.S. (1974) Cavity dumped argon ion laser as an excitation source in time resolved fluorimetry. Analytical Chemistry, 46, 855 860. 

Some applications of time-resolved fluorimetry using streak cameras will now be considered in order to illustrate the various possibilities available to the photochemist. The ps decay of the acridine singlet state has been determined as a function of temperature and solvent using the third harmonic of a mode-... 

Correlation based approaches to time-resolved fluorimetry have been reviewed by Hieftje and Haugen. Despite the apparent low costs of the equipment and the reasonable time resolution, little application of the methods were evident. 

Recently, a highly sensitive immunoassay based on the time resolved fluorimetry was developed for the analysis of MCs in water [169]. In order to improve the sensitivity and to simplify the procedure, this method uses a fluorescent lanthanide (Europium) for labeling the MC and the product of the reaction is detected with a time resolved fluorimeter. This method showed a more consistent response at the lowest concentrations and an equal sensitivity compared to the ELISA methods. 

By solving the inverse problem, the fluorescence lifetime r of a fluorophore can be determined independently from the dependence Nn(tdei). In the experiment the fluorescenoe signal is measured in relative units. For comparison of the experimental data with the theoretical ones it is necessary to normalize the obtained experimental curve to the fluorescence intensity at some fixed time delay. This procedure, the fluorimeter capabiUties in the kinetic mode and the corresponding theory can be found elsewhere (Banishev et al., 2006). The difference of such variant of kinetic fluorimetry from the conventional time-resolved fluorimetiy is that the fluorescence is excited by a pulse with rather long duration ( 10 ns), and for fluorescence registration an optical gated multichannel analyser is used. Whereas, the conventional time-resolved fluorimetry (Lakowicz, 1999) is based on the analysis of fluorescence decay curves after the excitation pnilse, whose duration is much shorter than the lifetime of a fluorophore in the excitation state (picoseconds). 

Europium Complex formation with 4,7-bis(chlorosulfophenyl)-1,10-phenanth roline-2,9-dicarboxylic acid 3x10- mol - Determination using microsecond time-resolved fluorimetry... 

Yuan J. L., K. Matsumoto. Synthesis of a new tetradentate beta-diketonate-europium chelate and its application for time-resolved fluorimetry of albumin, J. Pharm. Biomed. AruiL, 15, 1397-1403 (1997). 

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