JPS6239389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrolyte analysis method and an electrolyte analyzer in which a sample liquid is introduced into a flow cell through which a carrier liquid is passed, and an ion-selective electrode is used to analyze and measure an electrolyte in the sample liquid.

Conventionally, electrolyte components such as sodium, potassium, calcium, or chlorine contained in biological fluids have been measured using a discrete electrolyte analyzer that uses a probe-type ion-selective electrode and a reference electrode, but in recent years, the device configuration has changed. Continuous flow methods are attracting attention because they are simple and easy to operate. However, in the continuous flow type electrolyte analyzers that have been developed so far, there is a lot of dead space in the flow path from the sample intake section to the flow cell, which is the detection section. Because it diffuses into the liquid, a large amount of sample is required to obtain stable output. In addition, samples may adhere to the pipes along the way.
It may also cause carry over.

The conventional electrolyte analysis method will be further explained using drawings. FIG. 1 shows the configuration of a conventional flow cell type electrolytic analyzer. Standard samples 11 and 12 and a sample liquid 13, which also serve as carrier liquid, stored in the liquid tank are alternately sucked into the flow path from the sampling nozzle 10 via the switch 9 and guided to the flow cell 1. The sample is connected to each ion selective electrode 2, 2',
The output of each electrode is connected to an amplifier 18 between the 2" sensitive membranes 8, 8', 8" and the liquid junction 7 of the reference electrode 3.
The output is amplified by the arithmetic unit 19 and displayed on the display 20. The sample is sucked and discharged by the liquid feed pump 14. Each electrode contains an internal reference solution 5, 5', 5'' or a comparison solution 6, and an internal reference electrode 4, 4', 4'', 4 is inserted therein. The flow cell 1 is a liquid pump 14
By the operation of this pump 14, liquid is sucked through the nozzle 10, passes through the cell chamber 30 of the flow cell 1, and is discharged from the drain port 15.

According to such a conventional electrolyte analyzer, there are problems as shown in FIG. That is, FIG. 3 explains the state of sample spread in a conventional flow cell type electrolyte analyzer. Although the horizontal axis is shown in time, it may also be considered as the length of the piping or flow cell channel. What is shown by the solid line a is the concentration profile at the time when the sample is sucked into the suction nozzle, and what is shown by the broken line b is the concentration profile within the flow cell. At the time of sample injection, the concentration profile is almost trapezoidal, but while moving through the flow path piping, it diffuses into the standard solution, which is a carrier liquid that is located before and after the sample and moves at the same time as the sample, and reaches the inside of the flow cell. Sometimes the range in which the concentration is constant becomes narrower. Furthermore, when the response of the ion-selective electrode is slow, as shown in FIG. 4, the time period during which the electrode output becomes constant becomes even narrower than the concentration profile shown by the dotted line in FIG. Therefore, the amount of sample required for measurement is 3 times the volume of the flow channel of the flow cell.
It has to be more than doubled.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide an electrolyte analysis method in which diffusion of the sample liquid into the carrier liquid is extremely small even when the sample liquid is present inside the cell chamber of a flow cell. and equipment.

The present invention is characterized by stopping the flow of the carrier liquid flowing through the cell chamber where the sensitive surface of the ion-selective electrode is exposed during analysis and measurement of the sample liquid, and maintaining the flow of the carrier liquid in the stopped state. A sample liquid is injected into the cell chamber, and the electrolyte concentration in the sample liquid is measured while the injected sample liquid is present in the cell chamber.Then, the sample liquid in the cell chamber is removed from the cell chamber by a carrier liquid. This is due to the fact that it was made to be discharged.

A preferred embodiment of the present invention has a cell chamber through which a carrier liquid flows, an ion-selective electrode, and a reference electrode, such that the sensitive surface of the ion-selective electrode and the liquid junction of the reference electrode are exposed to the cell chamber. An electrolyte analysis system comprising: a flow cell section disposed; a means for transporting a carrier solution from a carrier solution source so that it flows through the cell chamber; and a signal processing section for processing an electrical output signal from an ion-selective electrode. Applies to equipment.
Further, on the carrier liquid flow path from the carrier liquid source until the liquid is discharged through the cell chamber, a flow path blocking means for substantially blocking one of the flow paths on the upstream side or the downstream side of the cell chamber is provided. A sample liquid inlet is provided on the carrier liquid flow path at a position closer to the cell chamber than the flow path closing means so that the sample liquid enters the cell chamber without being transferred by the carrier liquid.

Here, only one type of ion-selective electrode is sufficient to be exposed facing the cell chamber, but when measuring biological fluids, it is desirable to provide multiple types, for example, one for sodium, one for potassium, one for chlorine, etc. . Although a reciprocating pump or a syringe equipped with a check valve is used as the liquid feeding means, the present invention is not limited thereto, and other liquid feeding mechanisms such as a squeezing pump may also be used. In a preferred embodiment, the flow passage blocking means is also served by a liquid feeding pump;
A separate opening/closing valve may be provided, or the sample liquid can be injected in one direction within the channel even if the channel resistance on one side of the inlet and outlet of the cell chamber is significantly greater than the channel resistance on the other side. The sample liquid injection part may be a sample injection syringe connected to the carrier liquid flow path fixedly attached to the flow pipe or the end of the flow cell, or a diaphragm made of silicone rubber or the like that blocks the inside of the flow pipe from the atmosphere. An injection needle of an injection device containing a sample liquid may be inserted through the septum and inserted into the channel to inject the sample liquid. The carrier solution is usually a standard solution prepared so that the electrolyte concentration is at a predetermined value, but it is not limited to this, and the stability of the operation of the ion-selective electrode is determined by the presence of the electrolyte. It is only used because it is desirable for people.

FIG. 2 is a diagram showing a schematic configuration of an embodiment of the present invention. Components having the same functions as those in FIG. 1 are given the same reference numerals. A liquid sending pump 14 that sends standard solutions 11 and 12 as carrier liquids is connected to the flow cell 1.
It is placed on the upstream side of the carrier liquid flow path and also serves as a carrier liquid flow path blocking device. On the other hand, the drain port 15 is open to the atmosphere. The cell chamber 30 includes an ion selective electrode 2,
The ion-sensitive membranes 8, 8', 8'' of 2', 2'' and the liquid junction part 7 of the reference electrode 3 are exposed.

The liquid feed pump 14 is located between the standard solution switch 9 and the flow cell 1, and a sample injection port 21 integrated with the flow cell is installed on the upstream side of the flow cell. At the time of sample injection, the operation of the liquid feeding pump 14 is stopped, and the flow of the carrier liquid is stopped. The test fluid is directly injected into the measurement channel of the flow cell from a sample injection port 21 having a diaphragm using a microsyringe 22 or the like. The sample amount may be at least enough to fill the space between the sample injection port 21 and the liquid junction 7 of the reference electrode. The needle of the microsyringe 22 penetrates the septum of the injection port 21, and after the needle tip opening completely reaches the inside of the flow path, the sample liquid in the syringe is injected into the flow path. Since the flow path on the upstream side of the cell chamber 30 is blocked by the stopped liquid pump 14, the injected sample liquid fills the cell chamber toward the drain port 15 as it is injected. To go. The sample liquid is brought into contact with the ion-sensitive membranes 8, 8', 8'' and the liquid junction 7.The electrode output (potential) stabilizes approximately 10 seconds after sample injection, so read the displayed value at that stable point. Then, the liquid sending pump 14 is operated to send the carrier liquid to discharge the sample liquid in the cell chamber 30 from the liquid drain port 15.

FIG. 5 shows the electrode output in the embodiment device of FIG. 2, and the time axis has the same number of scales as in FIG. 4. The experiment was conducted with a flow cell channel volume of 30 μl and a sample injection volume of 50 μl. When the liquid pump was stopped and the sample was injected at point A, a slight concentration gradient appeared while the sample liquid was pumping out the carrier liquid that had been introduced into the cell chamber, but when the sample injection was completed, the electrode The output remained constant. When the liquid pump was operated again from point B, the electrode output returned to the output potential of the standard sample again in a short time.

According to this embodiment, the sample liquid can be injected into the cell chamber without being activated by the carrier liquid.
Diffusion of the sample can be reduced and analysis can be performed with a trace amount of the test. Furthermore, since measurement can be carried out sufficiently if the sample amount is about 1.3 to 1.5 times the volume of the flow cell channel, there is no need to reduce the channel volume extremely. In the embodiment shown in FIG. 2, the comparison solution 6 supplied to the liquid junction via the comparison electrode 3 is supplied using a water head.

FIG. 6 is a schematic configuration diagram of another embodiment of the present invention,
The liquid feed pump 14 and the sample injection port 40 are connected to the cell chamber 3.
The carrier liquid is located downstream of the carrier liquid.
After stopping the pump 14 and closing the downstream side of the flow path, when the sample liquid is injected from the microsyringe 22, the sample liquid heads toward the switch 9 and flows into the cell chamber 3.
Filled within 0. After electrolyte measurement, the pump 14 is operated to discharge the sample liquid through the sample discharge port 41. The comparison solution 6 of the comparison electrode 3 is supplied to the liquid supply pump 14'.
Supplied using In this embodiment as well, the amount of sample liquid to be injected may be about 1.3 to 1.5 times the volume of the cell chamber.

As explained above, according to the present invention, electrolyte components can be analyzed with less diffusion of the sample solution, so that measurement accuracy can be improved and the amount of sample can be reduced.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a conventional electrolyte analyzer, Figure 2
3 and 4 are diagrams showing the characteristics of the conventional system, FIG. 5 is a diagram showing the characteristics based on the embodiment of the invention, and FIG. FIG. 3 is a schematic configuration explanatory diagram of another embodiment of the present invention. 1...Flow cell, 2...Ion selective electrode, 3...
Reference electrode, 7... Liquid junction, 8... Ion sensitive membrane, 1
1, 12...Standard solution, 14...Liquid pump, 21,
40...Sample injection port, 30...Cell chamber.

Claims (1)

[Scope of Claims] 1. In an electrolyte analysis method in which a sample solution is stored in a cell chamber through which a carrier solution can flow, and the concentration of an electrolyte in the sample solution is measured using an ion-selective electrode, an ion-selective electrode is used. stopping the flow of the carrier liquid flowing through the cell chamber in which the sensitive surface is exposed; injecting the sample liquid into the cell chamber while the flow of the carrier liquid is stopped; An electrolyte analysis method comprising: measuring the electrolyte concentration in a sample solution while the sample solution is in a cell chamber; and discharging the sample solution in the cell chamber from the cell chamber using a carrier liquid. 2. A flow cell comprising a cell chamber through which a carrier liquid flows, an ion-selective electrode, and a comparison electrode, and arranged so that the sensitive surface of the ion-selective electrode and the liquid junction of the comparison electrode are exposed to the cell chamber. Department and
An electrolyte analyzer comprising means for transporting a carrier liquid from a carrier liquid source to flow within the cell chamber, and a signal processing section for processing an electrical output signal from the ion-selective electrode. Provided on the carrier liquid flow path from the liquid source to the discharge of the liquid through the cell chamber, a flow path closing means for substantially blocking one of the flow paths on the upstream side or the downstream side of the cell chamber, A sample liquid injection part is provided on the carrier liquid flow path at a position closer to the cell chamber than the flow path closing means so that the sample liquid enters the cell chamber without being transferred by the carrier liquid. An electrolyte analyzer featuring: