(redirected from Fluorometric)
Also found in: Dictionary, Medical.


An instrument that measures the fluorescent radiation emitted by a sample which is exposed to monochromatic radiation, usually radiation from a mercury-arc lamp or a tungsten or molybdenum x-ray source that has passed through a filter; used in chemical analysis, or to determine the intensity of the radiation producing fluorescence. Also spelled fluorimeter.



(also fluorimeter), an instrument used for measuring the decay time τ of fluorescence, which is approximately 10–8–10–9 sec. A fluorometer operates on the following principle. During high-frequency modulated excitation of luminescence, the luminescence is modulated at the same frequency as the excitation; however, because of the finite duration of the luminescence emission, the phase of the luminescence modulation lags behind that of the excitation modulation. In the case of excitation that is sinusoidally modulated at a frequency ω and fluorescence that decays exponentially, the phase angle φ = tan–1 (ωτ). The relation between the amplitude A0 of the excitation modulation and the amplitude A of the luminescence modulation is Fluorometer. Thus, to determine τ either φ or the ratio A0/A must be measured. If the decay is not exponential, the same method may be used to establish the mean lifetime of the excited state and to estimate the extent to which the decay is not exponential.

Figure 1. Schematic diagram of a phase fluorometer

The most widely used fluorometers are phase fluorometers, which measure φ (Figure 1). In an optical-excitation phase fluorometer, a light beam from a source (1) is focused on a modulator (2). A portion of the modulated flux is deflected by a semi-transparent plate (3) and enters a photomultiplier (5). The remainder of the flux is focused on a specimen (4) to excite fluorescence, which is deflected to another photomultiplier (6). The phase difference φ between the photoelectric currents from (5) and (6) is measured by means of a phase meter (7). A cathode-ray tube or phase detector (8) serves as the phase indicator. Fluorometers based on electron-beam and X-ray excitation have also been developed.

In an instrument that is more advanced than a fluorometer, luminescence is excited by short light pulses, and the decay curve is recorded directly.

Instruments that are used for luminescence analysis are also called fluorometers, or fluorimeters. Such instruments measure the intensity of luminescence and contain both a source for exciting the luminescence and a photometer.

References in periodicals archive ?
In order to evaluate if the compounds behaved as efflux pump inhibitors, an EtBr accumulation assay was carried out by a real-time fluorometric method using a Rotor-Gene 3000(tm) (Corbett Research, Sydney, Australia) (Viveiros et al.
The samples were analyzed for total aflatoxins using the VICAM AflaTest[R] immunoaffinity fluorometric method [17].
24] reported the decrease of fluorescence was obvious for fluorometric microorganisms in high concentration of certain toxics.
The fluorometric assay was conducted in a 96-well microplate.
The fluorometric microtitre plate assay was performed to determine the inhibitory activity of five S.
The presence of the umbelliferyl moiety in GALNS-S permits fluorometric assay of GALNS (2) by laboratories that do not desire to use ESI-MS/MS; however, such an assay will require that a glycohydrolase be added to act after the sulfatase.
Moreover, the spectra of the derivatives of Cys with SBD-F and SBD-BF, recorded with a Perkin-Elmer MPF 44 A spectrofluorimeter, were practically superimposable, suggesting that our new reagent SBD-BF is a suitable precolumn derivatization reagent for reversed-phase HPLC fluorometric determination of thiols.
With a product portfolio that includes Transfluor(R) technology, our Fluorometric Imaging Plate Reader (FLIPR(R)), and reagents, Molecular Devices now offers best-in-class screening solutions for every major type of GPCR target.
The design has been optimized to provide accurate, in-situ measurement of dissolved oxygen using phase fluorometric detection in real-time.
Fluorometric high-throughput inhibition assays of CYP enzymes are widely used for drug interaction screening particularly during the preclinical drug discovery stages.
Contract awarded for 17-hydroxyprogesterone oh neonatal screening methodology: fluorometric assay (delphia); use: laboratory diagnosis; reagent: yes; area: immunology;
Discusses the analytical methods for investigating the antioxidant properties of wheat grain and fractions and their phytochemical composition, including spectrophotometric and fluorometric methods and electron spin resonance (ESR) spectroscopy