JPH0515081Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an absorbance measuring device that includes a sample tank and a flow cell type absorbance measurement unit that communicates with the sample tank via a connecting tube. The present invention relates to a measuring device that can prevent air bubbles from being mixed in as much as possible, and thus can stably measure absorbance.

BACKGROUND ART Conventionally, as an apparatus for measuring the absorbance of a sample liquid using a flow cell, for example, one having the configuration shown in FIG. 5 is known.

That is, in FIG. 5, 1 is a closed type sample tank having an inclined bottom wall 1a, 2 is a coloring liquid introduction pipe connected to the sample tank 1 and interposed with an electromagnetic valve 3, and 4 is connected to the sample tank 1. A sample introduction pipe with an electromagnetic valve 5 interposed therein; 6 an air introduction pipe with an electromagnetic valve 7 connected to the sample tank 1; and 8 a discharge pipe with an electromagnetic valve 9 connected to the bottom of the sample tank 1. tube, 1
0 is a rotating shaft 12 attached to a rotating motor 11
This is an agitator with a propeller 13 fixed to the tip of the stirrer. Further, reference numeral 14 denotes an absorbance measuring section in which a light source 16 and a light receiving section 17 are arranged on both sides of the cylindrical flow cell 15, and one end side is inserted into the sample tank 1 in the inflow section 15a of the flow cell 15, The other end of a communication pipe 19 with an electromagnetic valve 18 interposed therebetween is connected, so that the sample liquid 20 in the sample tank 1 can flow into the flow cell 15 through the communication pipe 19. Note that one end 19a of the communication tube 19 is provided slightly apart from the bottom wall 1a of the sample tank 1. In addition, the outflow portion 15 of the flow cell 15
A discharge pipe 21 is connected to b, and the sample liquid that has flowed through the flow cell 15 is discharged to the outside of the system through this discharge pipe 21. Furthermore, 25 is an overflow pipe whose one end is connected to the upper part of the peripheral wall of the sample tank 1 and serves as an atmosphere opening for the sample tank 1, 26 is a solenoid valve installed in this overflow pipe 25, and 27 is a sample tank. The cleaning water introduction pipe 28 connected to the cleaning water introduction pipe 1 is an electromagnetic valve interposed in the cleaning water introduction pipe 27.

When measuring the absorbance of a sample using the above device, first open the valves 3, 5, and 26, and
The valves 7, 9, 18, and 28 are closed, and the coloring reagent and sample are introduced into the sample tank 1 through the coloring reagent introduction tube 2 and the sample introduction tube 4, and are stirred to prepare the sample liquid 20. Note that if the sample does not require a coloring reaction, there is no need to introduce a coloring reagent.

Next, open the valves 7 and 18, close the valves 3, 5, and 26, and connect the air introduction pipe 6 to the sample tank 1.
By introducing air into the flow cell 1, the pressure of the air causes the sample liquid 20 to pass through the communication tube 19 and into the flow cell 1.
Transfer within 5. As a result, the sample liquid flows through the flow cell 15 while co-washing the inside of the flow cell 15, and the transfer is stopped while the sample liquid 20 remains in the sample tank 1, and the absorbance is measured in the measuring section 14. be.

After the measurement is completed, the valves 7 and 9 are opened, and the valves 3, 5, 18, and 26 are closed, and air is introduced into the sample tank 1 from the air introduction tube 6, and the sample remaining in the sample tank 1 is removed by air pressure. After all of the liquid 20 has been force-fed and discharged through the discharge pipe 8, the valve 28 is opened, and the cleaning liquid is injected into the sample tank 1 from the cleaning water introduction pipe 27, stirred, and discharged in the same manner as when discharging the sample liquid. Drain and then perform the next measurement. In addition,
Even when the sample liquid is discharged from the sample tank 1, the connecting pipe 19
A sample liquid is retained in each of the flow cells 15 and 15 .

Problems to be solved by the invention When measuring absorbance using an absorbance measuring device equipped with a flow cell type measuring section as described above,
Preventing air bubbles from entering the flow cell is important for stabilizing the output signal of the light receiving section. In particular, when a cell with a long optical path length is used, the reproducibility of minute absorbance measurements often deteriorates, but according to the inventor's knowledge, this problem is caused by minute bubbles that are invisible to the naked eye in the flow cell. This was a result of the influx.

However, in the conventional measuring device described above, when the sample liquid 20 is discharged from the sample tank 1, the end 19a of the connecting tube 19 that exists inside the sample tank 1 is exposed to the air, so that Air bubbles 22 accumulate in the end 19a of the communication pipe 19, and when the sample liquid is transferred for the next measurement, the air bubbles 22 flow into the flow cell 15, and some or all of them adhere to and remain on the inner wall of the flow cell as air bubbles. However, there was a problem in that part of the measurement light was scattered, and as a result, the output signal of the light receiving section became unstable.

The present invention was developed in view of the above circumstances, and can effectively prevent air bubbles from entering the flow cell when the sample liquid is transferred to the flow cell, making it possible to stably measure absorbance. The purpose of the present invention is to provide an absorbance measuring device.

Means for Solving the Problems In other words, the present invention has the following objectives in order to achieve the above objectives:
It is equipped with a sample tank, a flow cell, a connecting pipe whose one end is connected to the sample tank and the other end to the flow cell, and a discharge pipe connected to the sample tank, and a sample liquid is sent from the sample tank to the flow cell through the connecting pipe. In an absorbance measuring device that discharges the sample liquid in the sample tank through a discharge pipe after measuring the absorbance of the sample liquid in the flow cell, a small-volume recess into which the sample liquid can flow is formed in a part of the inner wall of the sample tank. The opening of one end of the communication pipe is disposed within the recess.

Function: In the present invention, a recess into which the sample liquid can flow is formed in a part of the inner wall of the sample tank, so that when the sample liquid in the sample tank is discharged through the discharge pipe, the sample liquid remains in the recess. Furthermore, since the opening at one end of the connecting tube is disposed within the recess, the opening at one end of the connecting tube is present in the sample liquid remaining in the recess.
Therefore, even when the sample liquid is discharged from the sample tank, the opening at one end of the connecting tube is not exposed to the air, and therefore air is prevented from entering the one end of the connecting tube. This air can be retained in one end of the tube and prevented from flowing into the flow cell.

Furthermore, in the device of the present invention, since the capacity of the recess is formed to be small, the amount of sample liquid remaining in the recess when the sample liquid is discharged is extremely small compared to the total amount of sample liquid, and even if the sample liquid remaining in the recess is Even if it gets mixed into the sample solution for measurement, it will have almost no effect on the next measurement. Also, in reality,
When the flow cell is co-washed, the sample liquid in the recess first flows into the flow cell, and then the sample liquid around the recess flows into the flow cell, so the previous sample liquid in the recess, including the part that diffused around the recess, is co-washed. It is almost completely expelled. Therefore, according to the device of the present invention,
It is also possible to accurately measure absorbance by eliminating the adverse effects caused by contamination with the previous sample solution.

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

Embodiment 1 FIG. 1 shows an embodiment of the present invention. In addition, the first
In the figure, the same reference numerals are given to the same parts as in FIG. 5, and the explanation thereof will be omitted (the same applies to the second embodiment described later).

In the absorbance measuring device shown in Fig. 1, sample tank 1
A small-capacity approximately hemispherical recess 23 is formed in a part of the bottom wall 1a of the
is formed, and the end 19a of the communication pipe 19 is inserted into the recess 23 from the upper end opening thereof, so that one end opening of the communication pipe 19 is disposed within the recess 23.

Therefore, even when the sample liquid in the sample tank 1 is discharged from the discharge pipe 8, if the valve 18 is closed, the sample liquid 20 remains in the recess 23 as shown in FIG. One end opening of the connecting tube 19 exists in the sample liquid 20 remaining in the sample liquid 20, and the connecting tube 19
The opening at one end is not exposed to the air, and therefore air does not enter into the end 19a.

Example 2 FIG. 3 shows another embodiment of the invention.

In this embodiment, a substantially hemispherical small-capacity recess 2 is formed in a part of the bottom wall 1a of the sample tank 1, as in the first embodiment.
3 is formed, and an end 19a of the communication tube 19 is connected to the bottom of the recess 23 from outside the sample tank 1, so that one end opening of the communication tube 19 is disposed within the recess 23.

Therefore, if the valve 18 is closed, the sample liquid 20 remains in the recess 23 when the sample liquid is discharged as shown in FIG. Since the opening exists and the opening at one end of the communication pipe 19 is not exposed to the air, air does not flow into the one end 19a of the communication pipe 19.

In the devices of Examples 1 and 2 above, since the opening at one end of the communication tube 19 exists in the sample liquid 20 remaining in the recess 23 when the sample liquid is discharged, air cannot enter into the one end 19a of the communication tube. Therefore, air does not flow into the flow cell 15 during sample liquid transfer. Therefore, according to the apparatuses of Examples 1 and 2, absorbance can be measured stably and accurately by eliminating interference caused by air bubbles flowing into the flow cell.

In the apparatus of the above embodiment, the recess 23 is formed on the bottom wall 1a of the sample tank 1, but the location where the recess is formed is not limited, and the recess may be formed on the side wall of the sample tank 1, for example. Further, various changes may be made to other configurations without departing from the gist of the present invention.

Hereinafter, the effects of the present invention will be specifically illustrated by experimental examples.

Experimental Example Using the apparatus shown in Figure 1, silica was measured using the molybdenum blue method using ultrapure water as a sample. Further, for comparison, measurements were carried out in the same manner using the apparatus shown in FIG. The results are shown below.

Device of the present invention (Fig. 1) n=32, absorbance=7.070mABS, δ=
0.067mABS n=32, silica=4.202ppb, δ=0.039ppb Conventional device (Figure 5) n=47, absorbance=4.515mABS, δ=
0.585mABS n = 47, silica = 2.711ppb, δ = 0.343ppb From the above results, standard deviation around several mABS (absorbance) =
In contrast, the device of the present invention can achieve a standard deviation of 0.06 mABS. In addition, in silica measurement, standard deviation =
Achieved 0.04ppb (approximately 10 times the reproducibility of conventional equipment),
It has been found that the device of the present invention has sufficient accuracy as a monitor of ultrapure water.

Effects of the invention As explained above, the absorbance measurement device of the invention can prevent air bubbles from entering the flow cell, and can also eliminate the negative effects of the previous sample liquid. It is possible to perform absorbance measurements stably and accurately. In this case, the device of the present invention is particularly effectively used for measuring ultratrace components, and can measure minute absorbance with good reproducibility.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing one embodiment of the present invention;
The figure is an enlarged sectional view showing one end of the connecting pipe in the same example, and the third
The figures are a schematic diagram showing another embodiment of the present invention, FIG. 4 is an enlarged sectional view showing one end of the connecting pipe of the same example, FIG. 5 is a schematic diagram showing an example of a conventional absorbance measuring device, and FIG.
The figure is an enlarged cross-sectional view showing a state in which air remains at one end of the communication pipe of the same example. DESCRIPTION OF SYMBOLS 1...Sample tank, 2...Coloring liquid introduction tube, 4...Sample introduction tube, 8...Discharge tube, 14...Absorbance measuring section, 15...Flow cell, 16...Light source, 17
...Light receiving part, 19...Connection tube, 20...Sample liquid,
22...air, 23...recess.

Claims (1)

[Scope of utility model registration request] It is equipped with a sample tank, a flow cell, a connecting pipe whose one end is connected to the sample tank and the other end to the flow cell, and a discharge pipe connected to the sample tank, and a sample liquid is sent from the sample tank to the flow cell through the connecting pipe. In an absorbance measuring device that discharges the sample liquid in the sample tank through a discharge pipe after measuring the absorbance of the sample liquid in the flow cell, a small-volume recess into which the sample liquid can flow is formed in a part of the inner wall of the sample tank. 1. An absorbance measuring device characterized in that a connecting tube is formed in the recessed portion and an opening at one end of the connecting tube is disposed within the recessed portion.