JP2017207421A - Atomic Absorption Spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To verify in a posterior manner the state of inside of a furnace prior to the measurement of a sample.SOLUTION: An atomic absorption spectrophotometer comprises an atomization part, a light source, a detector, an optical system, a camera, and a photographing data storage part. The atomization part includes a tube-like furnace for heating a sample injected into the inside of the furnace for atomization. The light source emits light having a wavelength of measuring object toward the atomization part so that the light passes through the inside of the furnace. The detector detects the light passing through the furnace. The camera photographs the inside of the furnace before a measurement process is performed for atomizing the sample in the furnace and measuring the absorbance. The photographing data storage part stores photographed data obtained by photographing of the camera in association with measurement data corresponding to the photographed data.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an atomic absorption spectrophotometer used for quantitative analysis of metal elements.

  One atomic absorption spectrophotometer uses a tube furnace made of graphite. Such an atomic absorption spectrophotometer is used to inject a sample into the furnace using an instrument such as an injection needle from a small hole provided in the furnace, and then heat the furnace according to a predetermined temperature raising program. Atomize. At this time, the measurement light from the light source consisting of a holocathode lamp is irradiated into the furnace and allowed to pass through the atomic vapor, and the light passing therethrough is detected by a detector, whereby the absorbance at a specific wavelength due to the atomized sample component is obtained. Measure (see Patent Document 1).

JP 2004-325341 A

  In the above-mentioned atomic absorption spectrophotometer, when measuring an unknown sample, the optimal analysis conditions of the sample are not known, and therefore, sample boiling or sample injection failure occurs when the furnace is heated. Sometimes. In that case, the user will know such an abnormality from the variation in the measurement data, but since the cause cannot be confirmed afterwards, it is necessary to investigate the cause and determine the analysis conditions again. And took time.

  Therefore, an object of the present invention is to make it possible to verify the state in the furnace before the measurement of the sample afterwards.

  The atomic absorption spectrophotometer according to the present invention has a tube-shaped furnace, and an atomization part that heats and atomizes a sample injected into the furnace, so that light passes through the furnace, A light source that emits light having a wavelength to be measured toward the atomization unit, a detector that detects light that has passed through the furnace, and light having the wavelength to be measured out of light from the furnace is guided to the detector. An optical system, a camera for photographing the inside of the furnace before the measurement step of atomizing a sample in the furnace and measuring the absorbance thereof, and photographing data obtained by photographing the camera, An imaging data storage unit that stores the measurement data corresponding to the imaging data in association with the measurement data.

  By the way, since the shooting data acquired by the camera is a moving image, a large-capacity storage area is required to store all the data. However, if the measurement is performed normally, there is no need to verify the process of sample injection or temperature increase afterwards. Nevertheless, it is useless to store all the shooting data.

  Therefore, in the present invention, it is determined whether or not the measurement data obtained by the detector in the measurement step is normal, and the photographing data photographed by the camera immediately before the measurement step related to the normal measurement data is photographed. It is preferable to further include a photographing data organizing unit that is deleted from the data storage unit. By providing such a shooting data organizing unit, shooting data that the user does not need to verify later can be deleted from the shooting data storage unit, and accumulation of extra shooting data in the shooting data storage unit can be suppressed. An area for storing can be secured.

  The photographing data organizing unit determines whether the measurement data is normal by comparing a preset threshold value with a signal intensity of the measurement data or a value calculated based on the signal intensity. It may be configured as follows. Then, it is easy to determine whether the measurement data is normal. The “value calculated based on the signal intensity” includes, for example, the peak value of the absorbance calculated based on the signal intensity, and the standard deviation value of the absorbance in the case of repeated measurement.

  When determining whether or not the measurement data is normal based on the absorbance peak value, the measurement data is determined to be abnormal when the absorbance peak value falls below the threshold value. On the other hand, when determining whether or not the measurement data is normal based on the standard deviation value, the measurement data is determined to be abnormal when the standard deviation value exceeds a predetermined threshold value.

  As a further preferred embodiment of the present invention, a camera drive mechanism for moving the camera between a shooting position on the optical path of light from the light source and a non-shooting position off the optical path of light from the light source; From the time the sample is injected into the furnace to the time when the measurement process is performed on the sample, the camera is placed at the imaging position and the interior of the furnace is imaged by the camera. And a photographing control unit that controls operations of the camera and the camera driving mechanism so that the camera is arranged at the non-photographing position when executed. According to such a mode, it is possible to automatically perform photographing inside the furnace.

  The atomic absorption spectrophotometer according to the present invention includes a camera that images the inside of the furnace before the measurement process is performed, and an imaging data storage unit that stores the imaging data in association with the measurement data obtained in the measurement process. Therefore, verification of whether or not the sample has been normally injected into the furnace and whether or not bumping of the sample has occurred can be performed after the analysis is completed.

It is a block diagram which shows roughly one Example of an atomic absorption spectrophotometer. It is a flowchart which shows an example of the measurement operation | movement of the Example. It is a flowchart which shows the organizing operation | movement of the imaging | photography data of the Example.

  An embodiment of an atomic absorption spectrophotometer will be described with reference to FIG.

  The atomic absorption spectrophotometer of this embodiment includes a holocathode lamp 2 as a light source, an atomizer 4, a spectrometer 8, a photomultiplier tube 10 as a detector, a camera 12, a camera driving mechanism 14, an amplifier 16, an analog A digital converter (A / D converter) 18, an arithmetic control unit 20, an operation unit 22, and a display unit 24 are provided. Although not shown, appropriate condensing optical systems are disposed between the holocathode lamp 2 and the atomizing unit 4 and between the atomizing unit 4 and the spectroscope 6, respectively.

  The atomization unit 4 includes a graphite tube 6 as a furnace. A sample injection hole (not shown) is provided in the upper portion of the graphite tube 6. The graphite tube 6 is atomized by heating the sample to a high temperature when a large current is applied. The holocathode lamp 2 is provided on one end side of the graphite tube 6, emits light including a bright line spectrum toward the graphite tube 6, and passes the inside of the graphite tube 6.

  The spectroscope 8 includes an entrance slit (not shown), a diffraction grating, and an exit slit (not shown). The spectrometer 8 guides the light that has passed through the graphite tube 6 and is incident from the entrance slit to the diffraction grating and splits the light. Light is emitted from the exit slit and guided to the photomultiplier tube 10.

  The camera 12 has a position on the optical path of light from the light source 2 toward the graphite tube 6 by the camera driving mechanism 14 (hereinafter, this position is referred to as an imaging position) and a position off the optical path (hereinafter, this position is referred to as a non-imaging position). It moves between. The camera drive mechanism 14 has an arm that holds and operates the camera 12 and moves the camera 12 by operating the arm by driving a motor.

  An electrical signal obtained by photoelectric conversion by the photomultiplier tube 10 is amplified by the amplifier 16, converted to a digital signal by the A / D converter 18, and then input to the arithmetic control unit 20.

  An operation unit 22 and a display unit 24 are electrically connected to the arithmetic control unit 20. The user inputs various information to the arithmetic control unit 20 via the operation unit 22. The arithmetic control unit 20 displays information such as measurement data on the display unit 24. The arithmetic control unit 20 is realized by a dedicated computer or a general-purpose personal computer.

  The arithmetic control unit 20 includes a measurement data processing unit 26, a measurement data storage unit 28, a light source control unit 30, an atomization control unit 32, an imaging control unit 34, an imaging data storage unit 36, an imaging data organizing unit 38, and a threshold value storage. Part 40 is provided. The measurement data processing unit 26, the measurement data storage unit 28, the light source control unit 30, the atomization control unit 32, the imaging control unit 34, and the imaging data organizing unit 38 execute the program stored in the storage area of the arithmetic control unit 20 as an arithmetic device. Is a function obtained by executing. The photographing data storage unit 36 and the threshold storage unit 40 are functions realized by the storage area of the arithmetic control unit 20.

  The measurement data processing unit 26 processes measurement data based on a signal from the photomultiplier tube 10 input to the arithmetic control unit 20 via the amplifier 16 and the A / D converter 18. The processed measurement data is stored in the measurement data storage unit 28.

  The light source controller 30 generates light having a wavelength used for measurement from the holocathode lamp 2 by adjusting the voltage applied to the holocathode lamp 2.

  The atomization control unit 32 causes the atomization unit 4 to perform a temperature raising operation, an ashing operation, and an atomization operation based on a preset temperature raising program after the sample is injected into the graphite tube 6. It is configured. The temperature raising operation is an operation for gradually raising the temperature of the graphite tube 6 to a predetermined temperature (for example, 600 ° C.). The ashing operation is an operation of drying the sample by maintaining the temperature for a certain time after the temperature raising operation. An atomization operation | movement is operation | movement which atomizes a sample by raising the temperature of the graphite tube 6 to further high temperature (for example, 2500 degreeC), after ashing operation is complete | finished.

  The imaging control unit 34 is configured to control the imaging operation of the camera 12 and the movement operation of the camera 12 by the camera driving mechanism 14. Specifically, from the stage of injecting the sample into the graphite tube 6, the camera 12 is placed at the photographing position, and photographing inside the graphite tube 6 is started. Imaging in the graphite tube 6 continues until the ashing operation of the sample is completed. When the ashing of the sample is finished, the photographing of the camera 12 is stopped and the camera 12 is moved to the non-photographing position. The imaging data in the graphite tube 6 acquired by the camera 12 is stored in the measurement imaging data storage unit 36 in a state associated with the measurement data of the absorbance of the sample that is atomized and measured thereafter.

  The imaging data organizing unit 38 deletes unnecessary imaging data from the imaging data stored in the imaging data storage unit 36 after a series of analysis operations is completed. Whether or not the shooting data is necessary is determined based on whether or not the measurement data associated with the shooting data is normal. If the measurement data is normal, it is determined that the shooting data is unnecessary. Whether or not the measurement data is normal is determined based on whether or not the absorbance peak value or the standard deviation value in the measurement data exceeds a preset threshold value stored in the threshold value storage unit 40. If the measurement data is normal, there is no need to perform verification afterwards such as the presence or absence of sample injection failure or the presence or absence of sample bumping, so that the imaging data becomes unnecessary.

として表すことができる。ｘ_avgは測定した吸光度の平均値であり、xiは各回の測定で得られた吸光度値とする。このほか、しきい値として、例えばバックグラウンドによる吸収値や吸光度値そのものなどを使用することができる。 As a threshold for determining whether or not the measurement data is normal based on the standard deviation value, for example, a variation coefficient CV of the number of repetitions calculated by the following equation can be used.
CV = 100 × s / x _avg
Here, s is the sample standard deviation, and in the case of n repeated measurements,

Can be expressed as x _avg is the average value of the measured absorbance, and xi is the absorbance value obtained in each measurement. In addition, as the threshold value, for example, the background absorption value or the absorbance value itself can be used.

  The arithmetic control unit 20 causes the display unit 24 to display the photographing data stored in the photographing data storage unit 36 in addition to the measurement data subjected to the arithmetic processing by the measurement data processing unit 26 and stored in the measurement data storage unit 28. be able to. The measurement data stored in the measurement data storage unit 28 and the shooting data stored in the shooting data storage unit 36 are associated with each other, and when the user finds abnormal measurement data via the display unit 24. The photographing data relating to the measurement can be easily read out from the photographing data storage unit 36 and reproduced.

  Next, a series of operations of the atomic absorption spectrophotometer will be described with reference to the flowcharts of FIGS. 2 and 3 together with FIG.

  First, a predetermined voltage is applied to the holocathode lamp 2 to generate measurement light. Before performing the sample injection operation, the camera 12 is placed at the photographing position on the optical path of the light from the holocathode lamp 2 toward the graphite tube 6 to start photographing inside the graphite tube 6 (step S1). Thereafter, a sample is injected into the graphite tube 6 (step S2).

  After injecting the sample, the temperature raising operation of the graphite tube 6 (step S3) and the sample ashing operation (step S4) are executed. At the timing when the ashing operation of the sample is finished, the photographing by the camera 12 is finished, and the camera 12 is moved to the non-measurement position (step S5). By moving the camera 12 to the non-measurement position, the light from the holocathode lamp 2 blocked by the camera 12 passes through the graphite tube 6 and is guided to the photomultiplier tube 10. At this time, the atomization unit 4 performs an atomization operation in which the graphite tube 6 is heated to a higher temperature to atomize the sample, and the light from the holocathode lamp 2 passes through the generated atomic vapor. The absorbance of the converted sample is measured (step S6). The step of measuring the absorbance of the atomized sample is called a measurement step.

  After the above measurement process is completed, the measurement data obtained by the photomultiplier tube 10 and the photographing data obtained by the camera 12 are stored in the measurement data storage unit 28 and the photographing data storage unit 36 in a state of being associated with each other. Remembered. If there is a sample to be measured next, the above-described series of analysis operations are performed on the sample. After the measurement of all samples is completed, the photographic data stored in the photographic data storage unit 36 is organized (step S9).

  As shown in FIG. 3, in order to organize the photographing data, first, the measurement data stored in the measurement data storage unit 28 is read (step S11), and the absorbance peak of the sample is detected (step S12).

  If no peak is detected from the measurement data, it is possible that the sample has not been normally injected into the graphite tube 6 or that the sample has bumped during the temperature raising operation and the sample has been scattered. It is determined that the data is not normal (step S13). In this case, the corresponding shooting data associated with the measurement data is left in the shooting data storage unit 36 without being deleted.

  Even if a peak is detected from the measurement data, if the peak value falls below a preset threshold value, defective sample injection into the graphite tube 6 or bumping of the sample during a temperature raising operation is considered. Then, it is determined that the measurement data is not normal (steps S13 and S14). Also in this case, the corresponding shooting data associated with the measurement data is left in the shooting data storage unit 36 without being deleted.

  As described above, whether or not the measurement data is normal can be determined based on the standard deviation value. When determining whether or not the measurement data is normal based on the standard deviation value, the measurement data is determined to be abnormal when the standard deviation value exceeds a predetermined threshold value.

  If the peak value of the measurement data exceeds the threshold value, it is determined that the measurement data is normal (step S14), and the shooting data associated with the measurement data is deleted from the shooting data storage unit 36. The above operation is performed for all data (step S16), and unnecessary shooting data stored in the shooting data storage unit 36 is deleted.

  In the embodiment shown in FIG. 1, when photographing the inside of the graphite tube 6, the camera 12 is disposed between the holocathode lamp 2 and the atomizing unit 4 so as to directly photograph the inside of the graphite tube 6. However, the image may be taken indirectly through a mirror.

  Further, the camera 12 may be arranged between the atomization unit 4 and the spectrometer 8. In that case, in order to prevent the photographing from the camera 12 from being impossible due to the light from the holocathode lamp 2, the holocathode lamp is at a timing when the camera 12 is disposed between the atomization unit 4 and the spectroscope 8. 2 can be configured such that a shutter that blocks light from 2 is disposed between the holocathode lamp 2 and the atomization unit 4.

2 Holocathode lamp 4 Atomization unit 6 Graphite tube 8 Spectrometer 10 Photomultiplier tube 12 Camera 14 Camera drive mechanism 16 Amplifier 18 A / D converter 20 Arithmetic control unit 22 Scan unit 24 Display unit 26 Measurement data processing unit 28 Measurement Data storage unit 30 Light source control unit 32 Atomization control unit 34 Imaging control unit 36 Imaging data storage unit 38 Imaging data organization unit 40 Threshold storage unit

Claims (4)

An atomization section that has a tube-shaped furnace and heats and atomizes the sample injected into the furnace;
A light source that emits light of a wavelength to be measured toward the atomization unit so that light passes through the furnace;
A detector for detecting light passing through the furnace;
An optical system that guides light having a wavelength to be measured out of light from the furnace to the detector;
A camera that images the inside of the furnace before the measurement step of atomizing the sample in the furnace and measuring the absorbance thereof is performed;
An atomic absorption spectrophotometer comprising: an imaging data storage unit that stores imaging data obtained by imaging by the camera in association with measurement data corresponding to the imaging data.   It is determined whether or not the measurement data obtained by the detector in the measurement step is normal, and the shooting data shot by the camera immediately before the measurement step related to the normal measurement data is deleted from the shooting data storage unit The atomic absorption spectrophotometer according to claim 1, further comprising a photographing data organizing unit.   The photographing data organizing unit determines whether the measurement data is normal by comparing a preset threshold value with a signal intensity of the measurement data or a value calculated based on the signal intensity. The atomic absorption spectrophotometer according to claim 2 configured as described above. A camera drive mechanism for moving the camera between a shooting position on an optical path of light from the light source and a non-shooting position off the optical path of light from the light source;
Between the time when the sample is injected into the furnace and the time when the measurement process is performed on the sample, the camera is placed at the imaging position and the inside of the furnace is imaged by the camera, and the measurement process is executed. 4. The imaging control unit according to claim 1, further comprising: an imaging control unit configured to control operations of the camera and the camera driving mechanism so that the camera is arranged at the non-imaging position when being performed. Atomic absorption spectrophotometer.

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