JPH0711484B2 - Atomic absorption spectrophotometer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an atomic absorption spectrophotometer, and more particularly to an atomic absorption spectrophotometer characterized by an atomization part.

(B) Conventional technology In general, an atomic absorption spectrophotometer includes a light source, an atomization unit including a burner and a means for spraying a sample into the flame of the burner, and a light passing through the flame from the light source. Equipped with a photometer that receives light and a data processing device that detects the substance concentration in the sample from the photometric value when the sample is sprayed.The received light value from the light source when the sample is not sprayed on the burner and when the sample is sprayed on the burner. The concentration of a certain substance contained in the sample is measured by using a calibration curve stored in advance in the data processing device based on the absorbance obtained by the photometric value.

(C) Problem to be Solved by the Invention In the above atomic absorption spectrophotometer, when the concentration of the substance contained in the sample is large, the absorption of light passing through the flame becomes large, and a calibration curve of the photometric value and the concentration is obtained. Since the concentration is identified in the part where the linearity is poor, accurate measurement cannot be performed. Therefore, conventionally, when the concentration of the sample is high,
Dilute the concentration in advance with a predetermined ratio, or manually change the burner angle appropriately to change the degree of light passing through the flame,
As a result, the photometric value was adjusted so as to be obtained at a linear position on the calibration curve.

However, when adjusting the concentration of the sample by diluting it, it is necessary to memorize the ratio, and when changing the angle of the burner manually, it is necessary to reset the calibration curve each time the angle is changed. , There was a problem that it took a lot of work.

The present invention has been made in view of the above problems, and an object thereof is to provide an atomic absorption spectrophotometer capable of ensuring a predetermined measurement accuracy even when the concentration of a sample is high.

(D) Means and Actions for Solving the Problems The atomic absorption spectrophotometer of the present invention comprises a light source, an atomization unit including a burner and a means for spraying a sample into the flame of the burner, and a light source from the flame. In a device provided with a photometric unit for receiving light passing through the device and a unit for detecting the concentration of a substance in the sample from the photometric value at the time of spraying the sample, the angle of the burner is changed with respect to the optical path from the light source. A burner angle drive means, a control means for controlling the burner angle drive means so that the photometric value becomes constant, and a calibration curve of the substance concentration and the burner angle are stored, and the photometric value is kept constant using this calibration curve. Characteristically, there is provided a data processing section for performing data processing such as density calculation from the burner angle at the time.

This atomic absorption spectrophotometer has a high absorbance when the concentration of the sample is high. By controlling the burner angle driving means according to this absorbance, that is, the photometric value, the burner angle is changed to obtain the photometric value. The concentration is measured from the burner angle so as to be constant, and the concentration can always be measured within the linear range, and accurate measurement can be performed.

(E) Examples Hereinafter, the present invention will be described in more detail with reference to Examples.

FIG. 1 is a schematic block diagram of a spectrophotometer showing an embodiment of the present invention.

This atomic absorption spectrophotometer receives a light source 1, a detector 4 for detecting light from the light source 1, a photometric unit 5 for measuring a signal from the detector 4, and an output signal from the photometric unit 5. A data processing unit 6 for performing data processing such as density calculation, and a light source 1.
And an atomization part 2 including a burner for emitting a flame 2'having a narrow width in the longitudinal direction in the optical path of the detector 4 and a spraying means for spraying a sample into the flame 2 ', and the angle of the atomization part 2 The control unit 7 controls the drive unit 3 according to the data from the data processing unit 6 or the value input from the operation unit 9, the display unit 8 and the operation unit 9 described above. ing.

A calibration curve in the normal mode is stored in the memory of the data processing unit 6. This detection line has a horizontal axis of density and a vertical axis of measured value. Further, the concentration is plotted on the horizontal axis and the calibration curve of the burner angle is also stored on the vertical axis, which are features of the present invention.

As shown in the schematic external view of FIG. 2, in the atomization section 2, the burner 21 and the flame blowout section 22 are substantially on the same line as an optical path not shown, and the angle of the burner section with respect to this optical path ( The burner angle) is stepped by the step motor 31 of the drive unit 3 so that the angle can be adjusted appropriately.

Next, the software configuration of the atomic absorption spectrophotometer of the above embodiment and the overall control operation will be described with reference to the flow chart shown in FIG.

First, at the start of the operation, the control unit 7 sends a control signal to the drive unit 3 to spray the sample on the flame 2'of the burner 21 (step ST1). Then, in a state in which this sample is sprayed, the absorbance of the light detected by the detector 4 through the flame 2'from the light source 1 is measured by the photometry unit 5, and the data processing unit 6 makes the absorbance larger than a predetermined value. It is determined whether or not (step ST2).
When the absorbance is higher than the predetermined value, it means that the concentration is too high. On the contrary, when the absorbance is smaller than the predetermined value, it means that the concentration is low. This step ST
If the absorbance is greater than the predetermined value in 2, that is, if the concentration is high, the determination is YES and the process moves to step ST3 to increase the burner angle. That is, the burner flame is displaced in the long axis direction with respect to the optical axis to form an angle. Then, in step ST4, it is determined whether the burner angle is larger than a predetermined value.
This is because when the angle control of the burner angle reaches a predetermined limit angle, it is determined that the burner angle cannot be adjusted, and an alarm output is issued in step ST11 to end the control. If it is within the predetermined angle, the process returns to step ST2, and the processing operation of increasing the burner angle is continued until the absorbance is not higher than the predetermined value. As a result of increasing the burner angle or when the absorbance is not greater than the predetermined value from the beginning, the determination in determination step ST2 is NO, and then it is determined whether the absorbance is equal to the predetermined value (step ST5).

If the absorbance is equal to a predetermined value, it means that the photometric value is in the linear calibration curve part and that it is a proper photometric value.In this state, the concentration is extracted by referring to the calibration curve from the burner angle. Then (step ST6), the density value is displayed on the display unit 8.

On the other hand, if the absorbance is extremely smaller than the predetermined value, the determination in step ST2 is NO, the determination in step ST5 is NO, and in this case, the burner angle is decreased on the contrary (step
ST8). Next, it is judged whether or not the burner angle is the minimum (step ST9), and when the burner angle is the minimum, that is, 0, it is impossible to adjust any more. The concentration is extracted from the calibration curve table of and the result is displayed on the display unit 8 (step ST
7). If the burner angle is not the minimum, the determination in step ST9 is NO, the process returns to step ST2, and thereafter, the process of step ST2 → step ST5 → step ST8 → step ST9 is repeated until the absorbance becomes equal to a predetermined value, and the burner angle is reduced. I will do it. Eventually, when the absorbance becomes equal to the predetermined value, the determination in step ST5 becomes YES, and in the same way as when the angle was increased, the concentration is extracted by referring to the calibration curve from the burner angle in step ST6 and displayed. It will be displayed on the part 8.

(F) Effects of the Invention According to the present invention, a burner angle drive means for changing the angle of the burner with respect to the optical path from the light source, a control means for controlling the burner angle drive means so that the photometric value becomes constant, and a substance A calibration curve of the concentration and the burner angle is stored, and a data processing unit that performs data processing such as concentration calculation from the burner angle when the photometric value is constant using this calibration curve is provided, and the photometric value,
In other words, the burner angle is changed according to the sample concentration so that the photometric value is controlled to be constant, so that even if the sample concentration is high, accurate measurement can be performed without the need for dilution. .

[Brief description of drawings]

FIG. 1 is a block diagram of an atomic absorption spectrophotometer showing an embodiment of the present invention, FIG. 2 is an external view of an atomization part of the atomic absorption spectrophotometer, and FIG. 3 is an atomic absorption spectrophotometer. It is a flowchart which shows the atomization part process operation of a photometer. 1: Light source, 2: Atomization unit, 3: Driving unit, 4: Detector, 5: Photometry unit,
6: data processing unit, 7: control unit, 8: display unit, 9: operation unit.

Claims (1)

[Claims] 1. A light source, an atomization unit including a burner and means for spraying a sample into a flame of the burner, a photometric unit for receiving light passing through the flame from the light source, and a spraying unit for spraying the sample. In the atomic absorption spectrophotometer including means for detecting the substance concentration in the sample from the photometric value, the burner angle drive means for changing the angle of the burner with respect to the optical path from the light source, and the photometric value becomes constant. As described above, the control means for controlling the burner angle driving means and the calibration curve of the substance concentration and the burner angle are stored, and data processing such as concentration calculation from the burner angle when the photometric value is constant is stored using this calibration curve. An atomic absorption spectrophotometer, comprising: a data processing unit for performing.