JPS592338B2 - Flow type liquid sample analysis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid sample analysis method, and in particular to a flow type liquid sample analysis method suitable for electrochemically measuring ions, etc. in a channel system equipped with a flow cell. .

The ion selective analysis method, which is one of the liquid sample analysis methods, includes a flow method and a batch method, and the present invention relates to the flow method.

Conventional flow methods either flow the sample solution so that a fresh sample solution is always in contact with the ion-selective electrode or stir the sample solution.
It was considered preferable to do so, and the actual device was constructed that way. FIG. 1 is a flow path diagram of a conventional flow type ion selective analyzer.

The standard solution 6 is sent by a liquid pump 4, passes through a hexagonal valve 2, passes through a flow cell 1, has its ion concentration measured at 10, and is discharged as a drain 8. On the other hand, during this period, the amount of sample liquid is sent by the liquid sending pump 5, and is discharged through the hexagonal valve 2 and the measuring tube 3 as a drain 8. Next, when the six-way valve 2 is rotated 600 times, 15
The standard solution 6 passes through the channel, pushes out the sample solution in the weighing tube 3, and flows through the flow cell 1, so that the ion concentration of the sample solution T is measured. On the other hand, the amount of sample liquid sent by the liquid sending pump 5 flows through a channel in the six-way valve 2 shown by the dotted line, and is discharged as a drain 8. 20 Therefore, by rotating the six-way valve 2 600 times at regular intervals, the ion concentrations of the standard solution 6 and sample solution 1 are automatically measured.

The signal generated by such a conventional flow cell type ion selective electrode has a drawback 25 in that it contains a lot of noise.

This is thought to be caused by the pulsating flow of the liquid pump and the difference in electrical conductivity between the standard solution and the sample solution.The countermeasure for the former is to use a liquid pump with less pulsating flow, and for the latter. As a countermeasure, 30 methods of grounding using special ion-selective electrodes were attempted, but it was possible to completely eliminate noise, and the equipment was complicated. In general, in the flow cell type liquid analysis method that uses electrochemical detection means, even the pulsating flow of the liquid to be measured is
Noise removal is the most difficult.

However, since the pulsating flow has the effect of facilitating replacement and cleaning of the test liquid in the flow cell, this relationship is contradictory. An object of the present invention is to provide a flow-type liquid sample analysis method that can reduce noise and provide high measurement accuracy.

The inventors have confirmed through experiments that even if the flow of the test liquid is temporarily stopped, the output does not change for a short period of time. Therefore, in the present invention, immediately after the replacement of the test liquid in the flow cell is completed,
By temporarily stopping the flow of the test liquid, the above-mentioned contradictory relationships were made compatible.

FIG. 2 is an explanatory diagram of a flow cell type liquid analyzer which is an embodiment of the present invention.

A measurement electrode 10} and a reference electrode 11 are attached to the flow cell 1, and connected to an amplifier 20 by lead wires 12 and 13 shown in Figure D and dotted lines. Further, the output of the amplifier 20 is led to a recorder 21 by a lead wire 14. On the other hand, the controller 22 is connected to the recorder 21 by a lead wire 15, and is electrically connected to the nozzle mover 23 by a lead break 16 and to the suction pump 24 by a lead wire 17. . The inlet of the flow channel of the flow cell 1 is connected to the nozzle 25 via a nozzle mover 23 via a conduit 26, and the outlet of the flow cell 1 is connected to a drain pipe 28 via a conduit 27 and a suction pump 24. . The flow cell type liquid analyzer of this embodiment operates according to the time chart shown in FIG.

That is, when the suction pump 24 operates, the standard solution 6 is guided to the flow cell 1 through the nozzle 25 and fills the inside of the flow cell 1. This period is about 2.5 seconds. For the next approximately 0.5 seconds, the suction pump is stopped, the potential difference of the standard solution is measured, the output difference between the two electrodes is recorded on the recorder 21, and the nozzle 25 is moved to the sample solution 7. Next, suction pump 2
4 is operated for 2.5 seconds to replace the liquid in the flow cell 1 with the sample liquid 7, and then the operation of the suction pump 24 is stopped for about 0.5 seconds. During this time, the nozzle mover 23 is operated to move the nozzle 25 to the standard solution, and the sample solution is measured. This completes one measurement cycle, and all of the above operations are executed according to the program set in the controller 22. By exchanging the sample liquid 7 one after another using a fraction collector or the like and repeating the above measurement cycle D, it becomes possible to continuously and automatically analyze a large number of sample liquids. FIG. 4 is a diagram showing the output signal of the amplifier in the apparatus of FIG. 2 and the recording situation.

The vertical axis shows the output, and the horizontal axis shows the time in seconds, the scale of which matches the time scale of FIG. 3. Suction pump 2
The signal when the cell 4 is inhaling the standard solution 6 gradually decreases as shown by the line 30, but after about 1 second has passed and the inside of the flow cell 1 has been replaced with the standard solution, the signal remains almost constant. .
However, during this period, there is a lot of noise due to the influence of the pulsation of the suction pump 24, etc. In this way, when the suction pump 24 is stopped for about 0.5 seconds after 2.5 seconds have elapsed, most of the noise in the output signal A disappears. When this is performed, a bar graph 31 indicating the potential of the standard solution is recorded. When the suction pump 24 is operated again after 3 seconds have elapsed, the standard solution and sample solution are replaced, so the output gradually increases and eventually a flat plateau-like recording line is drawn.

In this way, after 5.5 seconds have elapsed, the suction pump 24 is
．． A 5 second pause produces a flat recorded line B. If you record the output at this time on a recorder in the same way as above, you will get
A bar graph 32 indicating the potential of the sample liquid 7 is obtained. Therefore, by comparing the outputs of the bar graphs 31 and 32, it is possible to know, for example, the ion concentration of the sample liquid. Although not shown in the diagram explaining the conventional flow type ion selective analysis method in FIG.
It is necessary to have a controller such as a timer for recording the par graph on a recorder.

Also, the conventional method requires two liquid pumps! Since the flow path is constantly flowing, a large amount of the liquid to be measured is consumed.
In other words, although the device of this embodiment shown in FIG. 2 requires a nozzle mover 23, only 241 suction pumps are required, and the flow path to the flow cell is connected with a thin tube to carry out the standard solution. This has the advantage of facilitating the replacement of the liquid and sample liquid in the flow cell. As described above, the flow cell type liquid sample analysis method of this embodiment has the advantage that the measurement accuracy is good and the device is relatively simple. The flow cell 1 shown in Figure 2 uses a pair of electrodes to analyze the concentration of one type of component, but if multiple electrodes are installed in the flow cell, multiple components in a sample solution can be analyzed simultaneously. It is possible to do so.

For example, when simultaneously measuring Na, K, and Ct concentrations in blood, the flow cell type liquid sample analysis method of the present invention can be achieved by installing each ion selection electrode in the same flow cell.
By measuring with the liquid to be measured in the flow cell stopped for a short period of time, highly accurate measurement is possible, and
Since a relatively simple automatic analysis device for liquid samples can be obtained,
Its industrial effects are significant.

[Brief explanation of drawings]

Fig. 1 is a flow path diagram of a conventional flow type ion selective analyzer, Fig. 2 is an explanatory diagram of a flow cell type liquid analyzer which is an embodiment of the present invention, and Fig. 3 shows the operation of the apparatus shown in Fig. 2. The time chart shown in FIG. 4 is a diagram showing the output signal of the amplifier in the apparatus of FIG. 2 and the recording situation. 1...Flow cell, 6...Standard solution, 7
...Sample liquid, 10...Measurement electrode, 11
...Reference electrode, 21 ...Recorder, 22
...Controller, 23...Nozzle mover,
24...Suction pump.

Claims (1)

[Claims] 1. Use a flow path system in which a movable suction nozzle is connected to a flow cell in which an electrochemical measurement electrode is arranged, and the movable nozzle is alternately positioned at a standard solution suction position and a sample liquid suction position at predetermined time intervals. , the standard solution and the sample are introduced alternately into the flow channel, and when the standard solution enters the flow cell, the flow of the solution is temporarily stopped, and the standard solution is electrochemically measured while the flow is stopped. After measuring the standard solution, move the liquid in the flow path and introduce the sample liquid into the flow cell, temporarily stop the flow of the sample liquid into the flow cell, and stop the flow. A flow-type liquid sample analysis method that involves electrochemically measuring a sample liquid during the process.