JPH051413B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention is directed to the relative positional relationship between the sample atomization section and the spectroscopic optical system in an atomic absorption spectrometer that atomizes the sample using flame or the like. Relating to a regulating device.

(b) Prior art In atomic absorption spectrometry, a sample is atomized at high temperature using a flame or a sample atomization reactor, and then light is passed through the atmosphere of the atomized sample to emit light of a specific wavelength by the atomized sample component elements. Although it measures absorption,
The concentration distribution of the sample component elements in the space where the sample is atomized is not uniform, and there are fluctuations in both the concentration distribution and the temperature distribution, so absorption measurements contain considerable noise. Therefore, during analysis, it is necessary to find a positional relationship between the sample atomization part and the spectroscopic optical system that provides as good sensitivity as possible and a large S/N ratio. In other words, in order to increase sensitivity, it is best to pass light through the sample atomization section so that the elemental concentration of the sample components is as high as possible in the sample atomization section and the passage path of the light is long. In the atomization section, light is allowed to pass through a region where fluctuations in concentration and temperature are small and stable. Conventionally, to adjust the positional relationship between the sample atomization unit and the spectroscopic optical system, an operator manually moves the position of the sample atomization unit while recording the measured absorbance value, and measures the sensitivity and S/N ratio. The method used was to find the positional relationship that seemed to be the most favorable. However, such manual position adjustment has a large number of subjective elements, requires the operator's attention, requires considerable skill, and is time-consuming.

(c) Purpose The present invention aims to automate the adjustment of the positional relationship between the sample atomization section and the spectroscopic optical system described above.

(D) Configuration When the absorbance value is relatively large, the atomic absorption spectrometer of the present invention gives priority to the S/N ratio and searches for the state where the S/N ratio is maximum, and when the absorbance value is small and the sensitivity is sufficient. When this is difficult to obtain, priority is given to sensitivity and the state where the absorbance value is maximized is searched, and the switching between giving priority to S/N ratio and sensitivity is automated. It has a control device that not only drives this mechanism but also detects and stores the position of the sample atomization section, and this control device is provided with data on the position of the sample atomization section and information on the light absorption while moving the sample atomization section. The data and the noise data are sampled and stored, and based on this storage, the maximum value of the S/N ratio and the corresponding position, and the maximum value of the absorbance data and its position are searched, and the maximum value of the S/N ratio is searched. If the corresponding absorbance is 1/k or more of the maximum absorbance value, the position where the S/N ratio is maximized is determined, and if it is 1/k or less, the position corresponding to the maximum absorbance data is determined as the optimal position of the sample atomization unit, and sample atomization is performed. The invention is characterized in that a control operation program is set to drive the part to that position.

(E) Example Figure 1 shows the vector component of the movement of the movement mechanism of the sample atomization section, F is the flame for sample atomization,
In this embodiment, the vector components of the movement are the vertical movement V, the horizontal movement H, and the rotation T about the vertical axis, and these movements are each controlled by a control device. FIG. 2 is a block diagram showing the overall configuration of an embodiment of the present invention. 1 is a light source, F is the flame of the sample atomization section mentioned above, 2 is a spectrometer, and 3 is a photometric element. The sample atomization section F has a left and right movement mechanism Dh,
Vertical movement mechanism Dv, rotation mechanism around the vertical axis Dt
These mechanisms are driven by a control device C. The output of the photometric element 3 is input to an absorbance converter 5 via a preamplifier 4 and becomes an absorbance signal. Since the absorbance signal contains noise as shown in FIG. 3, the noise component is removed by the averaging circuit 6 and the signal is stored in the memory M.
The absorbance signal is further input to a high-pass filter 7, which cuts out the DC component.
Only the noise is extracted, and the root mean square value is determined by the effective value conversion circuit 8. This data is data related to noise and is stored in the memory M. Memory M
Data h, v, and t regarding the position of the sample atomization section F are sent from the control device C, and these data are also stored.

FIG. 4 is a flowchart of the sample atomization section position adjustment operation of the control device C. This operation involves introducing the sample into the sample atomization section, moving the sample atomization section to the starting point of position scanning (a), and first rotating the sample atomization section around the vertical axis until the absorbance value is maximized. Detect the direction and set the orientation of the sample atomization unit F in that direction (B, C, D), then move the left and right movement mechanism Dh,
Drive the vertical movement mechanism Dv (F). This drive is performed by driving from one end of the movement range in the left-right direction to the other end, lowering the vertical position by one step, returning to the original position in the left-right direction, and repeating this operation to scan the position by zigzag movement. It is something to do. During this time, the position data is sampled (A), and at the same time, the average value of the absorbance signal, that is, the absorbance data that is the output of the averaging circuit 6, and the noise data that is the output of the effective value circuit 8 are also sampled (H), and the data are stored in the memory. Store in the corresponding address. This operation is performed until the judgment operation (E) becomes YES, and when the judgment operation (E) becomes YES, Dh and Dv are stopped,
Read the data in the memory M, find out the data at positions h and v where the S/N ratio is maximum, that is, the ratio of the output of circuit 6 and the output of circuit 8 is maximum (nu), and calculate the absorbance data and the maximum absorbance at that position. The absorbance at positions h and v is 1/ of the maximum value.
If k or more (judgment (o) is YES), Dh, Dv
is driven to set the sample atomization section F at the positions h and v above, and the operation is completed. That is, if the absorbance at the highest S/N ratio is 1/k or more of the maximum value of absorbance, select the one with the highest S/N ratio rather than the maximum value,
If it is 1/k or less, the one with the maximum absorbance is selected. If the judgment (e) is NO, the position where the absorbance value is maximum is detected (f), the sample atomization unit is driven to that position (y), and the operation ends.

In Fig. 2, the changeover switch Sw is brought into contact with the contact A side as shown in the figure for normal measurements, but measurements performed by switching to the contact E side are measurements in which the photometric output is not passed through the absorbance converter 5. In optical emission analysis using flame F and absorption analysis using a sample reactor such as a graphite reactor without using a flame, the positioning of the graphite reactor (a graphite reactor has a thin hole passing through it, (measurement is performed by passing through the hole), etc.

(F) Effect If you adjust the position of the sample atomization section while viewing the measurement output display on a meter or recorder as in the past, the response of the meter will be slow and the meter or recorder will be affected by noise caused by fluctuations in the flame. The instructions are always agitated;
The point of maximum sensitivity is relatively easy to find, but the position of maximum S/N ratio is very difficult to find. Moreover, it is not always advisable to adjust to the position with the highest S/N ratio; even if the S/N ratio is high, if the measurement output itself is too small, the sensitivity will be insufficient and measurement with a large number of effective digits will not be possible. In relation to the S/N ratio,
It is necessary to use the highest S/N ratio and the highest sensitivity, but it takes a lot of nerve for operators to make this distinction based on their personal judgment, and it is difficult for operators to compare different measurements using the same standard. It is also difficult to do so. However, according to the present invention, such a position is automatically determined and set simply by the position adjustment start operation. In addition, even when measuring the same element, differences in the physical properties of the sample may cause, for example, the amount of suction into the sample atomization section to vary, the temperature distribution in the flame may change, the optimum position for analysis may vary, or the coexistence of other elements may cause differences in the sample's physical properties. Depending on the difference in isochemical characteristics, it is better to change the combustion conditions of the flame, and in this case, the optimal analysis position will naturally differ, but when analyzing using an autosampler, it is better to change the flame combustion conditions manually. The adjustments were so complicated that it was impossible to adjust the position one by one, so we had no choice but to set the position to the greatest common divisor for various samples and various combustion conditions. However,
According to the present invention, even in such a case, each sample can be analyzed at its optimum position, and the accuracy and efficiency of analysis can be improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a perspective view showing vector components of movement of the sample atomization part, and FIG.
FIG. 3 is a block diagram showing the entire apparatus, FIG. 3 is a graph of the absorbance signal, and FIG. 4 is a flowchart showing the operation of the control device. F...flame for sample atomization, 1...light source, 3...photometric element, Dh, Dv, Dt...sample atomization section movement mechanism.

Claims (1)

[Claims] 1. A moving mechanism for moving the sample atomization unit, and sampling and storing absorbance data and noise data while driving the mechanism and moving the sample atomization unit, and based on these memories,
When the maximum value of the S/N ratio is detected and the absorbance data corresponding to the S/N ratio is greater than 1/k of the maximum value of the absorbance, the position corresponding to the maximum S/N ratio, 1 /k, the position corresponding to the maximum absorbance is determined to be the optimal position of the sample atomization section, and the sample atomization is performed at that position according to the data of the position corresponding to the maximum S/N ratio or maximum absorbance value. An atomic absorption spectrometer equipped with a control device having an operation program for moving parts.