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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.

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Critical re-appraisal of fluorometric method for determination of Selenium in biological materials.
Activities of caspase-8 and -9 were determined using fluorometric methods.
In the fluorometric assay the highly sensitive AR/HRP system has been used for assessment of [H.
1 shows the natural substrate and the substrates used in the MS/MS and fluorometric assays.
The samples were analyzed for total aflatoxins using the VICAM AflaTest[R] immunoaffinity fluorometric method [17].
The concentration of 4-hydroxynonenal (4-HNE), a marker of oxidative stress, was assayed as a fluorometric derivative with 1, 3cyclohexandione (CHD) separated on RP [C.
The objective of this study is to determine the fluorometric response of cyanobacteria in suspension to Cu in a short period of time.
After centrifugation at 1600 g for 15 min, the n-butanol layer was taken for fluorometric measurement at 553 nm with excitation at 515 nm.
Chemical quantitation of hemoglobin glycosylation: Fluorometric detection of formaldehyde released upon periodate oxidation of glycoglobin.
Attemps have been made to correlate sperm plasma membrane integrity to fertility, however, great variation is seen among methods used [8, 17, 23] and positive correlation between membrane integrity assessed by fluorometric methods and fertility has been observed [16].
Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay: TUNEL assay was performed using the DeadEnd Fluorometric TUNEL System kit as instructed by the manufacturer (Promega, Madison, WI, USA).