APPARATUS FOR THE MEASUREMENT OF FLUORESCENCE

Abstract: An apparatus for the measurement of fluorescence out of a liquid sample, the said apparatus comprising a source (1) of light, from which the light of measurement is arranged to be passed vertically through optics (2), a monochromator (3), and through the sample placed in a pit plate (4) to a measurement monochromator (5) and a detector (6). According to the invention, for each process of measurement, the source (1) of light, the optics (2), the monochromator (3), the sample to be measured, the measurement monochromator (5), and the detector (6) are arranged so that they can be brought onto the same vertical straight line in relation to each other, in this sequence.

Description: Apparatus for the measurement of fluorescence The subject of the present invention is an apparatus for the measurement of fluorescence out of a liquid sample, the said apparatus comprising a source of light, from which the light of measurement is arranged so as to be passed vertically through optics, a monochromator, and through the sample placed in a pit plate to a measurement monochromator and a detector. The samples have been dosed into small cuvettes, which may also be arranged in the form of a line or plate- The measurement takes place in the longitudinal axial direction of the cuvette so that the cuvette is placed in the apparatus in the space between the source of light required and the detector. In fluorometers, a monochromatic excitation light and a detector measuring the fluorescence radi¬ ation emitted from the sample are required. As a rule, in front of the detector, there is also some suitable monochromator, such as an interference filter or a grid. Since fluorescence radiation is emitted uniformly in all directions, in principle it can be measured from any direction whatsoever. A factor disturbing the measurement is the strong excitation light, wherefore attempts have been made to minimize its effect on the measurement result by means of various arrangements. -The commonest mode of measurement in use is the so-called 90° measurement geometry. -.Therein the directions of the excitation light and of the measure- ment are at an angle of 90 in relation to each other. In this way the access of direct excitation light to the detector is eliminated. The procedure in itself is simple, but it imposes considerable limitations on the geometry of the object to be measured. For example, the sample cuvettes can be treated only one by one or in the line form. It is also possible to measure the fluorescence radiation emitted by the surface by means of a particular arrangement. In this case, the direc¬ tions of excitation and measurement form a rather small (~ 10 to 20°) angle. Such a measurement geometry is usually used when the sample absorbs either the exci- tation radiation or the emitted fluorescence radiation strongly. The apparatus for the measurement of fluore¬ scence in accordance with the invention is mainly char¬ acterized in that, for each process of measurement, the source of light, the optics, the monochromator, the sample to be measured, the measurement monochromator, and the detector are arranged so that they can be brought onto the same vertical straight line in relation to each other, in this sequence. The invention comes out more closely from the following description and from the attached draw¬ ings, wherein Figure 1 is a schematical side view of the apparatus for the measurement of fluorescence and Figure 2 shows a section at A-A in Fig. 1. In the measurement arrangement in accordance with the present invention, the source 1 of light and the detector 6 are placed at opposite sides of the sample to be measured (Fig. 1) . The monochromator 5 in front of the detector 6 has been selected so that it is penetrable by the desired measurement wave-length λi only, but not by the excitation radiation λo producing the fluorescence. Such a measurement geometry is highly advantageous when such samples are. supposed to be measured as are dosed in a so-called pit plate 4. The pit plate 4 comprises 8 x 12 = 96 pits, whose volume is max. 300 μl. In the case of a plate, it is impossible to employ the 90° geometry. It is a further advantage of the through measurement that, since the source 1 of light, the sample in the pit plate 4, and the detector 6 can be brought very close to each other, in this way a strong measurement signal is obtained. The same apparatus can also be readily used for absorption measurements by omitting the measurement monochromator 5 placed in front of the detector 6. Also, by means of a suitable arrangement, it is possible to measure the absorption of the sample at the excita¬ tion wave-length λo and at the emission wave-length λi and to calculate an absorption-corrected fluorescence signal out of them. The most important requirement regarding the source 1 of light is a sufficient light intensity at the wave-length λo. Suitable sources of light are xenon or mercury gas-discharge lamps. Laser may also be used in some applications. In such a case, no monochromator 3 is required. As a detector 6, it is favourable to use a photomultiplier tube. As monochromators 3 and 5, it is possible to use interference filters or grids. The monochromator 3 and/or the measurement monochromator 5 are preferably exchangeable or removable out of the line of measurement.

Claims: WHAT IS CLAIMED IS: 1. An apparatus for the measurement of fluorescence out of a liquid sample, the said apparatus comprising a source (1) of light, from which the light of measurement is arranged to be passed vertically through optics (2) , a monochromator (3) , and through the sample placed in a pit plate (4) to a measurement monochromator (5) and a detector (6), c h a r a c - - t e r i z e d in that, for each process of measurement, the source (1) of light, the optics (2) , the monochro¬ mator (3) , the sample to be measured, the measurement monochromator (5) , and the detector (6) are arranged so that they can be brought onto the same vertical straight line in relation to each other, in this sequence. 2. An. apparatus as claimed in claim 1 , c h a r a c t e r i z e d in that the monochromator (3) and/or the measurement monochromator (5) can be exchanged or removed out of the line of measurement.

Inventors: VIRNES MARTTI, VIRNES, MARTTI
Applicants: EFLAB OY
Application year: 1982
Main classification: G01N21
IPC codes: G01N21