JPS6231879Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a spectrophotometer suitable for measuring temporal changes in absorbance.

When measuring suspended samples such as biological samples with conventional single-wavelength double-beam spectrophotometers, the baseline changes because the turbidity changes due to the addition of reaction reagents, making it difficult to observe changes in the spectrum. It was hot. Generally, changes in the baseline due to this turbidity are relatively slow and appear as changes in the slope that are approximately linear with respect to changes in absorbance and wavelength. The present invention aims to provide a spectroscopic device that can eliminate this baseline fluctuation and accurately measure temporal changes in spectra.

First, the principle of the present invention will be explained with reference to FIG.
In FIG. 1, the horizontal axis represents wavelength, and the vertical axis represents measured absorbance. In this figure, λ1 and λ2 are wavelengths that correct the temporal change in absorbance to zero. These wavelengths λ1 and λ2 are wavelengths at which the absorbance does not change depending on the reaction of interest. Let the absorption spectrum at the reference time, that is, the beginning of the measurement, be F(λ), and the values of F(λ) at wavelengths λ1 and λ2 are
Let them be A1 and A2. The straight line connecting A1 and A2 is f
(λ). Next, the spectrum after a certain period of time is G
(λ), the values at wavelengths λ1 and λ2 of G(λ) are B1 and B2, and the straight line connecting B1 and B2 is g(λ).
shall be.

Neither the line f(λ) connecting A1 and A2 nor the line g(λ) connecting B1 and B2 is the baseline itself. As a result of baseline fluctuation, f(λ) becomes g
(λ). Therefore, g of G(λ)
(λ) is the part where g(λ) is f
(λ), F(λ)
This means that G(λ) and G(λ) are compared on the same baseline, and the temporal change in the absorption spectrum becomes clear. In other words, to compare the absorbance Ax at the reference time at the wavelength λx and the absorbance after a certain time, Ax and
Instead of comparing with Bx, you should compare Bx minus Ax with Ax−(Bx−
) is the change in absorbance at wavelength λx.
is determined by the following equation.

=(B2-A2)(λ1-λx)+(B1-A1)(λx-λ2)/λ1-λ2 (1) Next, an embodiment of the present invention will be described with reference to FIG. 1 is a light source, 2 is a spectrometer, 3 is a sample cell, 4 is a photodetector, 5 is an amplifier, 6 is an A/D converter, and S is a changeover switch. 7 is a central control unit (CPU) that controls the entire device. When scanning wavelengths for the first time, the CPU 7 switches the switch S to the contact 1 side at wavelengths λ1 and λ2, samples the absorbances A1 and A2 at the wavelengths, and stores them at predetermined addresses in the RAM. Next, when performing wavelength scanning after adding the reagent, the switch S is switched to the contact 2 side by the CPU 7, and the spectrum G (λ) explained in FIG.
is stored in RAM. Then the wavelength λ in RAM
Using the values B1 and B2 of G(λ) for 1 and λ2 and the data of A1 and A2 previously stored in memory, the arithmetic circuit 8 performs the calculation of equation (1) above according to the instructions of the CPU 7, and calculates G(λx) based thereon. - calculation is performed for each wavelength and output to the recorder 9. By this operation, the recorder 9 records an absorption spectrum with no temporal change in the baseline at wavelengths λ1 and λ2 with absorbances A1=B1 and A2=B2.

Although it is troublesome to determine the baseline and the temporal change in the baseline, according to the present invention, there is no need to perform the operation of determining the baseline. If the baseline variation due to turbidity can be considered uniform, its influence can be completely removed.

In the above explanation, f(λ) and g(λ) are treated as straight lines, but if they can be expressed in other known function forms,
= g(λx) - f(λx), and the corrected absorption spectrum A(λx) is A(λx) = G(λx)
−{g(λx)−f(λx)} Further, the number of wavelengths at which the time change in absorbance becomes zero is not limited to two, and two or more wavelengths can be employed.

[Brief explanation of the drawing]

FIG. 1 is a graph explaining the operating principle of the device of the present invention, and FIG. 2 is a block diagram showing the configuration of an embodiment of the device of the present invention. 1... Light source, 2... Spectrometer, 3... Sample cell,
4...Photodetector, 8...Arithmetic circuit, 9...Recorder.

Claims (1)

[Scope of utility model registration request] A means for recording spectrum measurement values at a measurement reference time and an arbitrary time, a means for storing measurement values for a plurality of specific wavelengths at the measurement reference time, a line connecting the measurement values for the specific wavelengths at an arbitrary time, and a measurement for the measurement reference time. A spectrophotometer comprising a calculation means for subtracting the difference with a line connecting values from a measured value at an arbitrary time, and recording the output of the calculation means as a measurement value at an arbitrary time.