JPH04168348A - Emission spectrophotometer - Google Patents

Abstract

PURPOSE:To prevent dispersion in detecting sensitivity by storing the current values of the detected signals based on the emission of light from a sample, and controlling voltages to be applied so that the current value obtained by receiving the light of a fatigue lamp agrees with the stored value. CONSTITUTION:When light is emitted from a sample by spark discharge and the like, the light is reflected from a reflecting mirror 4a and cast on a grating 4b. The light is dispersed into spectral lights. The lights are received with photomultiplier tubes 6a - 6n, respectively. A CPU 14 applies specified voltages into the photomultiplier tubes 6a - 6n so as to obtain the desired sensitivities. The detected signals having the current values corresponding to the intensities of the spectral lights are outputted and digitized in A/D converters 10a - 10b. Thereafter the results are stored in a memory 12. Then, the CPU 14 stops the light emission of the sample and lights up a fatigue lamp 8. The signals corresponding to the amount of the light from the lamp 8 are outputted from the photomultiplier tubes 6a - 6n and received with the A/D converters 10a - 10n. The voltages applied on the photomultiplier tubes 6a - 6n are controlled so that the voltages agree with the stored values in the memory 12. Therefore, the response of the photomultiplier tubes 6a - 6n is quick in the sample analysis, and dispersion in sensitivity does not occur.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an optical emission spectrometer, and in particular, to an optical emission spectrometer that receives spectrum light unique to each element obtained by emitting light from a sample, and corresponds to the amount of received light. This invention relates to the control of a photomultiplier tube that outputs a light reception signal having a current value.

<Prior art> In general, in an optical emission spectrometer, a light emitting section emits light using a spark, etc. for a solid sample, and by plasma excitation, etc. for a liquid sample, and the light emitted by the light emitting section is separated into spectroscopy by a spectrometer. The spectral light unique to each element is received by each photomultiplier tube, a detection signal with a current value corresponding to the amount of light received is extracted, these detection signals are digitized, the integrated intensity is measured, and the measurement result is Quantitative analysis of the components contained in the sample is performed by comparing it with the calibration curve. In this case, since the detection sensitivity of the photomultiplier tube is related to the applied voltage, it is necessary to set the applied voltage to an appropriate value depending on the element content of the sample.

By the way, when performing routine analysis, the variety to be analyzed is almost constant, and the content of each component in the sample does not vary significantly and is limited within a certain range of components. Therefore, when analyzing approximately the same type of sample, conventionally the voltage applied to each photomultiplier tube is adjusted to a predetermined value in order to obtain an appropriate detection sensitivity within the component range of the sample of that type. is set to the value. And -
Once the applied voltage is set as above, the applied voltage will remain constant even if the sample is replaced, unless the product type changes and the component content of the sample differs significantly. ing.

On the other hand, when the sample is not in a luminescent state, such as when replacing the sample,
Although the current value of the detection signal from the photomultiplier tube is approximately zero,
Next, when the sample is caused to emit light, the photomultiplier tube outputs a detection signal having a current value corresponding to the intensity of the spectral light. In this way, when the current value of the photomultiplier tube changes significantly depending on whether or not the sample emits light, it takes time for the current to rise until it reaches the value corresponding to the component content. Therefore, responsiveness is lacking and detection sensitivity is insufficient.

Therefore, in the conventional technology, a single fatty lamp such as an incandescent lamp is provided, and as soon as the analysis of the sample is completed, this faty lamp is turned on to illuminate each photomultiplier tube, and when the sample is not emitting light, The photomultiplier tube also outputs a constant current.

<Problems to be Solved by the Invention> As mentioned above, in routine analysis, the voltage applied to each photomultiplier tube is usually maintained at a constant value, and therefore The magnitude of the current output from the photomultiplier tube differs depending on whether the light from the fatty lamp is received or the light from the sample is received. For example, in a photomultiplier tube that detects trace elements, the applied voltage is set high to increase the detection sensitivity, so when the amount of light emitted by the fatty lamp is large, the scale will be over-scaled.

In order to prevent this, by reducing the amount of light emitted by the Fatty lamp, the photomultiplier tube that detects elements with high content
The current value outputted when light from the fatty lamp is received is extremely small compared to when spectral light is received.

Therefore, when analysis is started by emitting light from the sample, although the detection response is somewhat improved compared to the case where no fatty lamp is provided, there is still a large change in the rise of the detection signal. There were disadvantages such as variations in detection sensitivity.

<Means for Solving the Problems> The present invention has been made in view of the above circumstances, and aims to further improve the detection response of a photomultiplier tube and prevent variations in detection sensitivity from occurring. It is something.

Therefore, the present invention includes a light emitting section that emits light from the sample, a spectroscopic section that spectrally spectra the light emitted by this light emitting section, and a spectroscopic section that receives spectrum light unique to each element separated by this spectroscopic section and responds to the amount of received light. In an optical emission spectrometer equipped with a photomultiplier tube that outputs a detection signal having a current value of storage means for storing current values of detection signals obtained by receiving spectrum light based on the photomultiplier tube with each photomultiplier tube; and storage means storing current values obtained by receiving light from the Fatty lamp by the photomultiplier tubes. The photomultiplier tube is configured to include a control means for controlling the voltage applied to each photomultiplier tube so as to match the current value set in the photomultiplier tube.

<Function> In the above configuration, the current values of the detection signals obtained by receiving each spectrum of light based on the light emission of the sample with the photomultiplier tube are stored in the storage means.

When the analysis of the sample is completed and the light emission stops, the Fatty lamp is turned on, but at this time, the control means has already stored in the storage means the current value obtained by receiving the light from the Fatty lamp with the photomultiplier tube. The voltage applied to each photomultiplier tube is controlled to match the current value.

In this state, when a new sample is caused to emit light, the content of each component in that sample has not changed significantly as long as routine analysis is assumed, so the spectral light is transferred to a photomultiplier tube. The current value of the detection signal obtained by receiving the light from the Fatih lamp does not change significantly from the current value obtained when the light from the Fatty lamp is received. Therefore, detection responsiveness is excellent.

<Example> FIG. 1 is a block diagram of an optical emission spectrometer according to an example of the present invention.

In the figure, reference numeral 1 indicates the entire emission spectrometer, 2 is a light emitting section that makes the sample emit light, and 4 is a spectroscopic section that separates the light emitted by the light emitting section 2, which includes a reflecting mirror 4a and a grating 4b. including. 63 to 6n are photomultiplier tubes that receive spectrum light unique to each element separated by the spectrometer 4 and output a detection signal having a current value corresponding to the amount of received light;
Reference numeral 8 indicates each photomultiplier tube 6 when the light emitting unit 2 is in a non-emission state.
Fatty lamp illuminating a to 6n, 10a
~IOn is an A/D converter that digitizes the detection signal of each photomultiplier tube 6a~6n.

Reference numeral I2 is a memory for storing the current value of the detection signal obtained by receiving the spectrum light based on the light emission of the sample by each of the photomultiplier tubes 6a to 6n, and 14 is a storage means for storing the current value of the detection signal obtained by receiving the spectrum light based on the emission of the sample by each photomultiplier tube 6a. The CPU serves as a control means for controlling the voltage applied to each of the photomultiplier tubes 6a to 6n so that the current value obtained by receiving light with the multiplier tubes 6a to 6n matches the current value stored in the memory 12.

In the above configuration, when the CPU 4 outputs a control signal to the light emitting unit 2 to cause the sample to emit light by spark discharge or the like, the light is reflected by the reflection mirror 4a of the spectrometer 4 and irradiated onto the grating 4b, and each element Dispersed into a spectrum of light with unique wavelengths. This dispersed spectral light is received by photomultiplier tubes 6a to 6n, respectively. A predetermined voltage is applied to each photomultiplier tube 6a to 6a by the CPU 14 so as to obtain a desired detection sensitivity. A detection signal with a corresponding current value is output. Then, this detection signal is sent to the A/D converter 1.
After being digitized by 0a-10n, it is taken into the CPU 14. The CPU 14 stores in the memory 12 the current values obtained by each of the photomultiplier tubes 6a to 6n.

Next, the CPU 14 stops the sample from emitting light and at the same time turns on the fatty lamp 8.

As a result, each of the photomultiplier tubes 6a to 6n outputs a signal having a current value corresponding to the light intensity from the fat granbe 8, and this signal is taken into the CPUI 4 via the A/D converter l0a to 10a. It can be done.

Therefore, the CPtJ 14 controls the voltage applied to each photomultiplier tube 6a to 6n so that this current value matches the current value already stored in the memory 12. When both types of current values match, the CPUI 4 maintains the voltage applied to each photomultiplier tube 6a to 6n at the value at that time.

To analyze the next sample, the CPU 4 causes the sample to emit light, simultaneously turns off the fatty lamp 8, and sets the voltage applied to the photomultiplier tubes 6a to 6n to the same value as when the previous sample emitted light. Set it again. In this case, the content of each component in the sample does not vary significantly as long as routine analysis is assumed, so the current value of the detection signal output from the photomultiplier tubes 6a to 6n is There is no significant variation from the obtained current value.

Therefore, the responsiveness of the photomultiplier tubes 6a to 6n is fast,
This means that sensitivity variations will not occur.

<Effects of the Invention> According to the present invention, the current value output from the photomultiplier tube does not change significantly depending on whether or not a sample is being analyzed, so the detection response of the photomultiplier tube is further improved. Ru. Therefore, excellent effects such as no variation in detection sensitivity can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical emission spectrometer showing an embodiment of the present invention. l...Emission spectrometer, 2...Light emitting section, 4...
Spectroscopic section, 68-6n... Photomultiplier tube, 8... Fatty lamp, 12... Storage means (memory), 14.
- Control means (CPU).

Claims (1)

[Claims] (1) A light emitting part (2) that makes the sample emit light, and this light emitting part (
A spectroscopic section (4) that separates the light emitted in step 2), and a spectroscopic section (4) that receives the spectrum light unique to each element separated by this spectroscopic section (4) and outputs a detection signal with a current value corresponding to the amount of received light. photomultiplier tubes (6a) to (6n), and the light emitting section (2).
), each photomultiplier tube (6a) to (
Detection obtained by receiving spectrum light based on the emission of the sample with each of the photomultiplier tubes (6a) to (6n). Storage means (12) for storing the current values of the signals, and photomultiplier tubes (6a) to (6) for transmitting the light from the fatty lamp (8).
Each photomultiplier tube (n) is adjusted so that the current value obtained by receiving light at
Control means (14) for controlling the applied voltages of 6a) to (6n)
), and an emission spectrometer characterized by comprising: