JPS61205849A - Method for measuring fluorescence - Google Patents

Abstract

PURPOSE:To detect fluorescence in a good S/N ratio with sufficient sensitivity, by totally reflecting exciting beam incident to the interior of a cell by the other surface of the cell and measuring fluorescence transmitted through the total reflective surface of exciting beam of the cell. CONSTITUTION:A specimen cell 1 receiving a solution 2 to be measured has, for example, a triangular cross-sectional area and, when exciting beam 3 is allowed to be incident to the interior of the cell 1 from one end surface 4 thereof, the exciting beam 3 transmits through the solution 2 in the cell 1 to be totally reflecting from the other end surface 6 of the cell 1. Fluorescence is generated by the irradiation of the solution 2 with exciting beam 3 but the fluorescence transmitted through the end surface 6, from which the exciting beam 3 was totally reflected, is directed to a detector to be detected. Because there is almost no exciting beam transmitted through the end surface 6 totally reflecting the exciting beam 3, it is markedly reduced that stray light other than fluorescence 7 is incident to the detector and it is unnecessary to place a filter in front of the detector and fluorescence can be detected in a good S/N ratio with sufficient sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fluorescence measurement method in which a solution-based sample is irradiated with excitation light and fluorescence generated from the solution is measured.

[Prior Art] Conventionally, in solution-based fluorescence measurement, a solution to be measured is sealed in a sample cell made of glass and having a square or circular cross section, and the cell is irradiated with excitation light. The solution in the cell generates fluorescence due to excitation light, and this fluorescence is measured by a detector placed perpendicular to the direction of irradiation of the excitation light, or by passing through a filter in the direction of irradiation of the excitation light. It is measured by a detector placed at

[Problems to be solved by the invention] In any of the measurement methods described above, it is inevitable that the excitation light enters the detector as stray light, and it is difficult to measure the SN with sufficient sensitivity.
Fluorescence cannot be detected relatively well. In particular, in a method in which excitation light is blocked by a filter, the decrease in sensitivity is remarkable.

The present invention has been made in view of the above-mentioned points, and its purpose is to detect fluorescence with sufficient sensitivity and a good signal-to-noise ratio.

[Means for Solving the Problems] The fluorescence measurement method based on the present invention is a fluorescence measurement method in which a sample cell containing a sample is irradiated with excitation light and the fluorescence generated from the sample is measured. It is characterized in that excitation light that enters the cell from one end surface of the cell is totally reflected by the other surface of the cell, and the fluorescence transmitted through the total reflection surface of the cell is measured.

[Operation] The sample cell containing the solution to be measured has, for example, a triangular cross section. Excitation light is input into the cell from one end face of the sample cell, and the excitation light passes through the solution within the cell and is totally reflected by the other end face of the cell. Of the fluorescence generated by the irradiation of the excitation light onto the solution to be measured, the fluorescence transmitted through the end face of the sample cell where the excitation light was totally reflected is directed toward the detector and detected. Almost no excitation light passes through the cell end face where the excitation light is totally reflected, and therefore, the incidence of stray light other than fluorescence entering the detector is significantly reduced, and there is no need to place a filter in front of the detector. Fluorescence can be detected with high sensitivity and high signal-to-noise ratio.

[Example] An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In the figure, 1 is a sample cell in which a solution sample 2 is sealed, and the cell has a triangular cross section and is made of glass. The excitation light 3 passes through one end face 4 of the cell 1 and enters the cell, passes through the sample 2 inside and reaches the other end face 6. The excitation light is reflected by the end face 6, and the shape of the cell and the angle of incidence of the excitation light into the cell are adjusted so that the excitation light is totally reflected by the end face 6.

Fluorescence is generated by irradiating the sample with excitation light, and the fluorescence 7 transmitted through the end face 6 is collected by an appropriate optical system (not shown) and detected by a detector.

Here, when the cross section of the cell 1 is an isosceles triangle and the refractive index of the glass is 1.5, the total reflection angle at the end face 6 is approximately 42 degrees from 5 in-11/1.5. In order for the excitation light 3 to be incident on the end face 6 at this angle, in the case of a triangular cell with two angles of 45°, it is necessary to
．． The excitation light may be incident on the cell 1 at an angle of 5° or more.

In this way, since the excitation light is totally reflected by the surface of the sample cell from which the fluorescence 7 is taken out, the excitation light is hardly mixed into the detected fluorescence as stray light, and the stray light is not present in front of the detector. There is no need to provide a filter to block the fluorescence, and it is possible to measure fluorescence with high sensitivity and with a good signal-to-noise ratio. Furthermore, since the cross-sectional shape of the sample cell is triangular, the amount of sample sealed in the cell can be reduced compared to cells having a square or circular cross-section.

Note that the present invention is not limited to the embodiments described above, and can be modified in many ways. For example, the cross-sectional shape of the sample cell is not limited to a triangle, but may be semicircular or trapezoidal.

[Effects] As described in detail above, according to the present invention, fluorescence can be measured with sufficient sensitivity and a good signal-to-noise ratio using a simple configuration in which excitation light is totally reflected.

[Brief explanation of drawings]

The accompanying drawing is a cross-sectional view of a sample cell used in one embodiment of the present invention. 1...Sample cell 2...Sample 3...Excitation light 4, 6...End face 7...Fluorescence

Claims (1)

[Claims] (1) In a fluorescence measurement method in which excitation light is irradiated into a sample cell containing a sample and the fluorescence generated from the sample is measured, the excitation light that has entered the cell from one end face of the cell is A method for measuring fluorescence, in which the excitation light of the cell is totally reflected by another surface and the fluorescence transmitted through the total reflection surface of the cell is measured.