JPS63145948A - Atomic absorption spectrochemical analyzer - Google Patents

Abstract

PURPOSE:To automate positional adjustment of a gas burner, by providing the gas burner with a moving means to control the moving means so that an absorption signal attains the max. value. CONSTITUTION:A burner 3 is set with a CPU at a reference position where a luminous flux thereof 3 passes the center of a flame 2 parallel with the length of the burner 3. The burner 3 is driven longitudinally by a burner position driver 8 from the position while the longitudinal position of the burner 3 and a data of an absorbance signal from an absorbance measuring circuit 7 are stored into the CPU. The CPU set the longitudinal position of the burner 3 to maximize the absorbance. Then, the burner 3 is moved vertically at the longitudinal position to be set at such a height as to maximize the absorbance. Moreover, the burner 3 is turned in place to be set at such an angle as to maximize the absorbance. In this manner, the CPU controls the device 8 to ensure the maximum of the absorbance signal of the circuit 7. This enables the automation of the positional adjustment of the burner 3 to make an operator free from complicated burner position adjusting operation thereby achieving a higher analysis efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an atomic absorption spectrometer that uses flame to atomize a sample.

In conventional atomic absorption spectrometry, the sample is atomized by a gas flame.
Depending on the temperature distribution, reduction region, oxidation region, etc. in the gas flame for sample atomization, there is a region most suitable for analysis of the sample. In atomic absorption spectrometry, the position of the flame relative to the beam of excitation light is adjusted so that the beam of excitation light passes through such an optimal region over the longest distance. Conventionally, such adjustments have been made manually by trying to find the optimum position by pressing the button incorrectly.

C6 Problems to be Solved by the Invention The flame position as described above is adjusted by moving the burner, but in that case, the burner position can be adjusted in the vertical direction, the horizontal direction perpendicular to the light beam, and the front-rear direction. ) and rotation around the vertical axis, and it is very complicated and time-consuming to do this manually.

An object of the present invention is to eliminate the above-mentioned complexity of manual burner position adjustment in atomic absorption spectrometry and to improve analysis efficiency.

20 Means for Solving Problems The burner is rotated vertically, in the 9 forward and backward directions (horizontal direction perpendicular to the optical axis of the passing light flux), and 31 in the vertical axis! ! A control means was provided to stop the burner at the maximum absorbance position by feeding back an absorbance signal from the photometry system in the burner position adjustment mode.

The flame used in Ho0 action atomic absorption spectrometry is formed by ejecting fuel gas from an elongated slit so that the horizontal cross section is a rectangular cross section that is long in the direction parallel to the passing light beam. Figure 2 shows a gas flame for atomic absorption spectrometry, where 0 is the center of the gas flame and F is the light flux passing through the gas flame. It is defined by two parameters. 0
If a fixed point at a constant height from the center of the gas burner's crater is taken as the point, H, B, and θ become parameters that define the position of the gas burner. When a standard sample is supplied into this gas flame, an absorbance signal is obtained from the photometric system.

When a minute drive signal is applied to the drive means for the three parameters of the gas burner to move the gas burner by a minute amount, the absorbance signal changes. Therefore, if the control system is operated in a direction that increases the absorbance, the gas burner will automatically settle at the optimum position.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. 1 is a light source that emits bright line light of the element to be quantified; 2 is a flame that atomizes the sample; and 3 is a burner that forms the flame 2. 4 is a spectroscope into which the light from the light source 1 that has passed through the flame 2 is incident.

5 is a photodetector for receiving light emitted from the spectrometer, 6 is a preamplifier, and 7 is an absorbance measurement circuit. The output signal of the absorbance measurement circuit 7 is read into a microcomputer CPU that controls the entire spectrometer. 8 is a burner position drive device, which consists of a pulse motor for driving the burner in the height direction, a pulse motor for driving the burner in the longitudinal direction, and a pulse motor for driving the angular position around the vertical axis of the burner. It is driven by the incoming drive pulse.

With the above configuration, when the CPU is set to the burner position adjustment mode, a standard sample is introduced into the burner 3, and the operation is started, the CPU performs the following operations. The burner 3 is initially installed at a position where the light flux passes through the flame center 0 in Figure 2 parallel to the longitudinal direction of the burner, and is first driven forward from that position (toward the front perpendicular to the paper in the figure). The data of the burner front and rear positions and the absorbance signal are stored in the CPU. This memorized data has a form as shown in FIG. Based on this data, the CPU sets the front and back positions of the burner to the positions where the absorbance is maximum. Next, at that longitudinal position, the burner is given a small vertical movement to detect the direction of movement in which the absorbance increases, and then the burner is moved in that direction and the absorbance and burner height position data are memorized. , Based on that data, set the burner at the height position where the absorbance is maximum. Next, at that position, the burner is rotated in one direction in a horizontal plane, and the burner is set at the angular position where the absorbance is maximum. This completes the burner position adjustment.

Since the relationships between the three burner movement directions and the absorbance are not mutually independent, the above-mentioned adjustment operation does not always result in a perfect absorbance maximum position. A more complete form of operation is described next. A flowchart of this operation is not shown in FIG. Starting the burner position adjustment operation of the CPU, using the same method as described above, first set the burner at the optimal position in the front-back direction (A), and then similarly set it at the optimal position in the vertical direction. (B) From that position, find the optimal position in the front and back direction again, and set it at that position (C)
From there, find the optimal position in the vertical direction again and set it at that position (d), then find the optimal position for the burner at that position and decide the angular position of the burner (e). Go to the next one
In step (e), move the burner slightly up and down and check to see if there is a change in absorbance (whether the change in absorbance is greater than the reference minute value).If there is no change, it is determined in step (e). Since the position is optimal, the movement ends there, and if there is a change, the optimal position in the front and back direction is moved from that position (
The operation is completed by setting the optimum vertical position (ji), and the optimum angular position (su). Although it may be possible to return to step (to) again after step (a), there is actually no need to do so. Also, the initial corner position adjustment (
The change in absorbance due to the angular position is small, and the interdependence between the front and back positions and the top and bottom positions is large. This is because since the independence is large, it is sufficient to adjust the angular position at a later stage.

G. Effect: Since the burner is provided with a moving means and a control device is provided to control the moving means so that the absorbance signal is maximized, the burner position adjustment is automated and the operator is freed from the complicated burner position B adjustment operation. , analysis efficiency has improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an apparatus according to an embodiment of the present invention, Fig. 2 is a perspective view of a flame, Fig. 3 is a graph showing changes in the absorbance signal when the position of the bar is changed, and Fig. 4 is a graph showing changes in the absorbance signal when the position of the bar is changed. It is a flowchart of the main operation|movement of CPU in other one Example of this invention. 1... Light source, 3... Burner, 4... Spectrometer, 7.
...Absorbance measurement circuit, 8...Burner position drive device, C
PU...Microcomputer. Agent: Hiroshi Agata, Patent Attorney Figure 1 Figure 3

Claims (1)

[Claims] A gas burner for sample atomization is provided with a driving device in each of the vertical, longitudinal, and rotational directions, and a control means is provided for driving the driving device in each direction so that the output signal of the absorbance measuring circuit is maximized. Absorption spectrometer.