JPH0566532B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for semi-quantitative analysis of elements using an emission spectrometer having a wavelength scanning function.

B. Prior Art Using an emission spectrometer having a wavelength scanning function, it is possible to qualitatively analyze the elements of a sample of unknown composition. However, in the case of luminescence analysis, unlike absorption analysis, the range of variation in the amount of light incident on the photometry system is very large, and if the gain of the photometry system is not set appropriately, the amplifier will become saturated and quantitative measurements will not be possible. .

Conventionally, when the element concentration in the analysis sample can be predicted to some extent, the gain of the photometry system is measured by measuring with a standard sample with the highest expected element concentration, and the sensitivity of the photomultiplier tube is adjusted to perform photometry. The gain was set to prevent the system amplifier from becoming saturated. However, when analyzing a sample whose concentration is completely unknown, there is no guideline for setting the gain of the photometric system in advance, so to avoid saturation of the amplifier, it is necessary to predict the maximum concentration higher, that is, set the gain lower. become. However, in this case, detection becomes difficult in the case of minute concentrations.
Another method is to set the gain appropriately, collect data as is if the amplifier does not saturate, and lower the gain if it does, but it is difficult to understand the relationship between the measured data before and after changing the gain. Without it, quantification cannot be performed. This is because in a photometry system that uses a photomultiplier tube, the gain of the photometry system is adjusted by changing the sensitivity of the photomultiplier tube, so the gain itself cannot be directly determined, and the gain can only be determined directly by the photomultiplier tube. Since it is a negative high voltage that is applied, if the relationship between this negative high voltage and the measured data is known, even if the negative high voltage is changed midway through, the data before and after can be processed uniformly. Since the characteristics of individual photomultiplier tubes vary greatly, it is recommended to display the relationship between the negative high voltage applied to the photomultiplier tube and the gain of the photometry system as a nominal characteristic of the analytical device as a product. It cannot be done. If you fix the sensitivity of the photomultiplier tube and adjust the gain of the amplifier, you can display the gain of the photometry system on the scale of the adjustment knob, and you can change the gain midway through the process. However, in this case, the output current of the photomultiplier tube may become excessive, so the photometry system is It is not desirable to change the gain of

In the end, conventional quantitative analysis of samples with unknown elemental concentrations was
The analysis sample is made to emit light and the wavelength is scanned. When the output of the photometric system is saturated, the negative high voltage of the photomultiplier tube is lowered to eliminate saturation. Next, in this state, a standard sample with known element concentration is measured. At this time, if the photometric system is fortunately not saturated, the element concentration of the analysis sample can be determined from the previously obtained measurement data of the analysis sample and the measurement data of the standard sample. However, when the photometric system becomes saturated during standard sample measurement, the gain of the photometric system must be further lowered to eliminate saturation, and photometry of the analytical sample must be performed again with the same gain. Therefore, quantitative analysis of unknown samples using luminescence spectroscopy has been extremely troublesome.

C. Problems to be Solved by the Invention The present invention is an emission spectrometer that eliminates the troublesomeness and inefficiency of the conventional method of repeating the measurement operation many times as described above, and allows the measurement of unknown samples in a single measurement operation. The aim is to develop a measurement method that can obtain measurement data that can be compared with standard samples.

D. Means to solve the problem Set the gain of the photometric system to a certain standard value that is appropriately determined, perform wavelength scanning on the analysis sample, record the photometric output, and even if the photometric output is saturated, the wavelength will remain unchanged. A record as shown in FIG. 1A is obtained by scanning. In this recording, assuming that there is a peak wavelength in the center between the saturation ranges a and b, the gain of the photometry system is lowered so that the saturation of the photometry system is eliminated at the wavelength at that point c, and with that gain, the peak wavelength is returned to the original saturation range a. , b, and at a wavelength position d or e near a, b. If wavelength scanning is performed with this gain, a record like that shown in Figure 1B can be obtained, but in this case, what is needed is the photometric output Ia at wavelength d or e in Figure 1 A and B.
and Ib and the photometric output Db in FIG. 1B at the peak wavelength c, and the photometric output Da at the wavelength c of the analysis sample with respect to the reference gain is determined by Da=Ia/Ib×Db (1).

E. Effect By the method described above, the measurement result of any sample can be normalized to the measurement value at the reference gain. If the measured values of both the standard sample and any other sample are normalized using the method described above, they can be compared directly and uniformly, making quantitative analysis easier. In the above explanation, the reference gain is specifically determined based on a certain value of the negative high voltage applied to the photomultiplier tube, and the operation described in section C is automatically controlled by a computer. It is executed by software.

Embodiment FIG. 2 shows an embodiment of the present invention. S is a light source that causes the sample to emit light, M is a spectrometer, P is a photomultiplier tube, and A is an amplifier. The output of A is the photometric output described above, which is read into the computer 2 via the A/D converter 1 The computer 2 stores the read photometric output data in the memory 3. H is a negative high voltage generating circuit which generates a negative high voltage according to a control signal from the computer 2 and applies it to the photomultiplier tube P. Dr drives the wavelength scanning mechanism of the spectrometer M with a drive device. Dr is controlled by computer 2.

FIG. 3 is a flowchart of the main part of the operation of the computer 2. When the device is started, a reference negative high voltage instruction signal is output to the negative high voltage generation circuit H, a reference negative high voltage is applied to the photomultiplier tube P (A), and the spectrometer is driven in the specified wavelength range. Then, the data shown in FIG. 1A is sampled and stored in the memory 3 (b). The data in FIG. 1A are wavelengths and their corresponding photometric outputs. When the wavelength scanning of the specified range is completed, it is checked in step (c) whether the photometric output is saturated. If it is not saturated (YES), the operation ends because data is obtained at the reference negative high pressure. When step (c) is NO, calculate the peak position of the spectral line, that is, the wavelength of point c in Figure 1, as described in section d above (d), and calculate the wavelength that is outside the saturation range and is closest to the saturation range. The photometric data Ia at the sampling point d in FIG. 1 is retrieved from the memory 3 and stored in the register (e). Next, adjust the negative high voltage at the wavelength point c until the photometric output falls below the saturation value (f). Then, read the photometric output Db in Figure 1B at that time (g).
Next, collect the photometric output Ib at the wavelength of point d in Figure 1, and use the data Ia and Da that were taken out earlier to calculate Da by calculating the equation (1) above. )
and store Da as standardized analysis data (nu)
to end the operation.

Although the above description has been made regarding one spectral peak, the above-described operation may be repeated for each peak in sequence for a plurality of peaks as well.

Effects According to the present invention, standardized measurement data for both standard samples and analysis samples can be obtained, so mutual comparisons can be made immediately, quantitative analysis is simplified, and concentration ranks can be uniformly determined even for samples with large concentration differences. Accordingly, analysis can be performed without the trouble of switching the measurements of the photometric system every time, and the operational burden on the operator is reduced.

[Brief explanation of the drawing]

FIG. 1 is a graph explaining the method of the present invention, FIG. 2 is a block diagram of an apparatus according to an embodiment of the present invention, and FIG. 3 is a flowchart of essential parts of the operation of a computer in the same embodiment.

Claims (1)

[Claims] 1 Set the gain of the photometry system to the reference value, measure and store the spectrum of the sample, and when the measurement output of the spectrum peak is saturated in the measurement,
Lower the gain of the photometry system until saturation is eliminated, calculate the ratio of the measured output at the reference gain at a wavelength point outside the saturation range and close to the edge of the saturation range, and the measured output after lowering the gain, and then calculate the gain. 1. An emission spectroscopic analysis method for normalizing measured data, characterized in that a measured value of a spectral peak at a reference gain is calculated by multiplying a measured value of a spectral peak after lowering by the above ratio.