JPS6348016B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an analytical method in which a standard addition method can be performed automatically.

Atomic absorption spectrometry is said to have relatively little interference from coexisting substances compared to plasma emission and colorimetric methods; Chemical interference and ion interference due to the coexistence of low ionization potential occur.

For samples with such interference, measurement errors can often be reduced by applying the standard addition method. In the conventional standard addition method, in order to create a calibration curve for each sample, multiple containers are prepared, the same amount of specific unknown sample is placed in all of them, and then a standard sample solution of known concentration is added to each container. Add so that the predetermined concentration changes. Add water to these containers to make the total volume constant, perform atomic absorption measurements, create a relationship line between concentration and absorption value, and use extrapolation to determine the content of the analyzed components.

The standard addition method cannot perform efficient measurements because a series of solutions must be prepared in multiple containers.

An object of the present invention is to provide an automatic standard addition analysis method that eliminates the need to prepare a series of standard addition samples using a plurality of containers and allows efficient analysis work.

The automatic standard addition analysis method of the present invention obtains a first mixed solution of a standard sample and a diluent in a flow path, and
A second mixed solution is obtained by mixing the mixed solution with the test sample solution at a fixed ratio, and the second mixed solution is led to the analysis section. It automatically changes to multiple stages while it is being supplied.

FIG. 1 is a diagram showing a schematic configuration of an embodiment of the present invention, and is an example applied to a flame atomic absorption spectrometer.

While the pump 15 is supplying a specific test liquid, the pump 12 changes its flow rate in multiple stages,
The amount of standard sample solution sent changes stepwise. If the pump 12 is a pump or a straining pump that is reciprocated by the rotation of a motor, a controller equipped with a microcomputer changes the number of revolutions of the motor according to time to change the amount of liquid sent. pump 13,
14 and 15 are kept at a constant flow rate during use. The diluent 10 is sent by a pump 13, mixed with a standard sample by a mixer 19, and then transferred to a sample collection container 16.
sent to. From the center of the sample collection container 16,
The pumped sample is introduced and the required amount is sent by the pump 14, and the excess amount overflows and is discharged into the drain 17. The test sample liquid or carrier reagent 11 is fed by a pump 15 and mixed with a diluted standard sample fed by a pump 14 in a mixer 18 . This mixed liquid is introduced into a sample suction container 8 having the same structure as the sample collection container 16, and is sucked from the center of the container by a nebulizer tube 5 by a nebulizer 4, and introduced into the flame through the burner chamber 3 and burner head 2. , measured by atomic absorption photometer 1. Then, the excess liquid that overflowed in the sample suction container 8 is discharged to the drain 17.

Various interference removal operations using the configuration shown in FIG. 1 will now be described.

(a) Calibration curve creation and simple dilution Distilled water is used as a carrier liquid instead of the test sample 11, and a standard sample solution 9 with a predetermined high concentration is used. Diluent 10 is distilled water.
The flow rate of the pump 12 is changed by 1, 2, and so on. This creates a calibration curve. Next, the sample is set and measured. In this case, the concentration can be calculated by memorizing the method of measuring the flow rate at what times the flow rate is measured.

(b) Creating a calibration curve and adding an interference suppressor Add an interference suppressor (for example, lanthanum in the case of measuring alkaline earth elements such as calcium in a sample that may contain phosphoric acid, silicic acid, or aluminum) to the carrier reagent 11. ) is used.
This is the same as in method (a) for creating a calibration curve, but a fixed amount of interference suppressor is mixed into both the standard solution and the sample. Thereby, even if the sample contains an interfering substance, the calibration curve method using the standard solution can be used.

(c) Calibration curve creation and component matching The main component solution contained in the sample is used as the carrier reagent 11. At this time, the concentration of the main component solution is made higher than the components in the sample. The method for creating a calibration curve is the same as in case (a), except that a fixed amount of the main component of the sample is mixed into both the standard solution and the sample. The concentration of the main component solution used as the carrier reagent is made high so that the difference in the main component due to the difference between the standard solution and the sample is reduced. If necessary, the main component solution used for the carrier reagent is also used as the diluent 10.

(d) Standard addition method Standard sample 9 at a predetermined high concentration is added by pump 12.
is sent and mixed with the diluent (distilled water) 10 in the flow path. The liquid mixture in the separation container 19 is mixed with the test sample 11 at a predetermined ratio. In order to form a series of second mixed liquids within the flow path, the pump 12 changes the amount of liquid fed in three stages. For example, the flow rate ratio of the pumps is set to three levels of 0, 5, and 10, and the flow rate ratio of the pump 13 is set to 50, the flow rate ratio of the pump 14 is set to 50, and the flow rate ratio of the pump 15 is set to 50. If a standard solution 9 containing 100 ppm of the target element is used, the target element concentration based only on the standard sample solution will be 0 ppm in the first stage, 5 ppm in the second stage,
The third stage will be 10ppm. While the standard sample is being changed in stages, the test sample liquid 11 is continuously pumped by the pump 15, so that at any stage there are two Contains a test sample diluted 2 times.

Analytical data obtained based on the three-stage mixture,
Based on the data obtained by using distilled water instead of the test sample solution 11, the concentration of the target element in the test sample is calculated by the calculation processing section, and the concentration of the target element in the test sample is calculated by extrapolation of the calibration curve, and is displayed on the display section. The results will be displayed.

The total flow rate of the mixed liquid supplied to the sample suction container 8 is set to be greater than the suction flow rate of the nebulizer 4. If it is difficult to accurately set the flow rates of these pumps, the difference in flow rate between each pump may be determined in advance and corrected after measurement.

By configuring the system as described above, it is possible to deal with interference in the atomic absorption spectrometer, only one type of standard sample is required, and there is almost no need to prepare measurement samples or containers. At the same time, error factors that occur in sample preparation (e.g., contamination by instruments and weighing errors)
It has the effect of removing.

FIG. 2 shows another embodiment of the present invention, and the difference from FIG. This is the result of the establishment of the . By setting the inner diameter and length of this mixing coil to values that match the present system, it is possible to improve the mixing of each solution and eliminate the pulsating flow of the pump. This embodiment has the effect of more stable solution mixing.

FIG. 3 shows another embodiment of the present invention, in which the calculation function section 23 and the pump control function section 2
A computer 22 having 4 computers is arranged. Since the calculation methods are different between the calibration curve method and the standard addition method,
Using computer 22 is effective.
In addition, creating a calibration curve by changing the flow rate of the pump 12, etc.
This is performed in response to a command from the pump control function section 24, and at the same time, the command is transmitted to the calculation function section 23, so that a calibration curve can be automatically created.
Furthermore, in the standard addition method, the flow rate of each pump can be accurately set by the computer 22, or the flow rate ratio can be stored in memory and corrected during calculation. In addition, by using a computer, it is possible to monitor the rollover phenomenon observed in Zeeman atomic absorption spectrometers (a phenomenon in which the signal becomes smaller than the maximum absorption when the sample concentration becomes very high). That is, by controlling the sample pump 12, samples are measured at different dilution ratios.

FIG. 4 shows a calibration curve for zinc measured with a Zeeman atomic absorption spectrometer. It is a straight line up to point C, and D
A curve is shown up to the point, and at higher concentrations, the absorption value becomes smaller. Therefore, when the measured value of the sample is around 0.3, points B and F are considered. If it is around B, the absorption value will become smaller by increasing the dilution factor. For example, if you measure a 2-fold diluted sample, A
Indicates the value near the point. This shows that it is within the normal calibration range. On the other hand, if the absorption occurs at point F, when a sample diluted twice is measured, the value will be around point E, which is in the abnormal range. and,
At this time, it is sufficient to attach a mark indicating an abnormality. In this way, it is possible to monitor the rollover phenomenon by measuring at least two or more dilution ratio samples with different concentrations. Of course, this method is possible without the computer 22, but
The results are judged by the analyst. In this example,
Furthermore, not only is it possible to create highly accurate calibration curves, perform standard addition method measurements, and perform automatic measurements, but it also has the advantage of being able to monitor rollover phenomena that occur in Zeeman atomic absorption spectrometers.

FIG. 5 is a schematic diagram of another embodiment of the present invention. A standard sample solution 9 with a predetermined high concentration is delivered by a pump 12 with a variable flow rate. Constant flow pump 1
4, the standard sample solution 9 and the diluent solution 10 are fed so that the sum of them is always a constant amount. Therefore, when the flow rate of the standard sample liquid 9 increases, the flow rate of the diluent 10 decreases, and the mixed liquid is mixed with the test sample liquid 11 at a predetermined ratio and sent to the sample suction container 8. In this embodiment, the number of pumps and sample collection containers can be reduced compared to the previous embodiment.

FIG. 6 shows an embodiment in which the sample suction container is omitted. A pump 14' is disposed in a flow path after the test sample liquid 11, diluted liquid 10, and standard sample liquid 9 are mixed, and the flow path is directly connected to the nebulizer nozzle 5. In this embodiment, the amount of mixed liquid sent to the nebulizer 4 is determined by the amount of liquid sent by the pump 14', and since the pump 14' and the nebulizer 4 are directly connected over a short distance, the amount of liquid sent to the nebulizer 4 is determined by the amount of liquid sent to the nebulizer 4. The suction amount is set to be less than the suction amount. For this example,
The sum of the flow rates of the test sample 11 and the standard sample liquid 9 is set to be equal to or less than the flow rate of the pump 14'.

As explained above, according to the present invention, liquids with different standard addition amounts of target components can be easily prepared in a flow path for the same test sample in stages, and a series of standard addition samples can be stored in a plurality of containers. There is no need to use .

[Brief explanation of drawings]

1, 2, 3, 5, and 6 are diagrams showing the schematic configuration of different embodiments based on the present invention, and FIG. 4 shows the relationship between component concentration and absorption sensitivity. It is a figure showing an example. 8... Sample suction container, 9... Standard sample solution, 10... Diluent, 11... Test sample solution, 12, 13, 14, 1
5...Pump, 16...Sample collection container.

Claims (1)

[Claims] 1. Aspirating the standard sample solution and the diluent into a flow path to obtain a first mixed solution of the standard sample and the diluent in the flow path, and introducing the test sample solution to obtain the first mixed solution. and the above-mentioned test sample liquid in a flow channel at a predetermined ratio to obtain a second mixed solution, guiding the above-mentioned second mixed solution to an analysis section, and containing the same test sample solution in the flow channel. An automatic standard addition analysis method comprising changing the mixing ratio of the standard sample and the diluent in multiple steps while the standard sample and the diluent are being supplied.