JPS62197758A - Electrochemical detector - Google Patents

Abstract

PURPOSE:To enable the prevention of the generation of bubbles in a measuring chamber while keeping a sample in a liquid to be measured from diffusion, by sandwitching a pressurizing section having a through hole with a small inner diameter between an electrode section and a reference section so as to cause a pressure loss of the liquid being measured at the pressurizing section. CONSTITUTION:A pressurizing section 11 is provided between an indication pole 2a and an opposed pole 2b and a reference pole 4. When introduced from an introduction pipe 9a, a liquid to be measured is led into the pressurizing section 11 via the indication pole 2a the opposed pole 2b and then, discharged through a lead-out pipe 9b via a liquid junction 12. With the inner diameter of the pressurizing section 11 noticeably noticeably smaller than that of the indication electrode 2a and the opposed electrode 2b, a piping resistance is generated, which pressurizes the liquid being measured through the indication electrode 2a and the opposed electrode 2b making it hard to generate bubbles in the liquid being measured. Moreover, as the inner diameter of the liquid junction 12 is larger than that of the pressurizing section 11, there will be a less pressure of the liquid being measured passing through the liquid junction 12. The liquid being measured will not reverse to an internal liquid 13 through the liquid junction 12 to obtain assuring a stable reference potential. This can prevent the generation of bubbles in the measuring chamber thereby in noway disturbing a plug flow of the liquid being measured.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrochemical detector that polarographically measures the concentration of an electrochemical redox substance.

<Prior Art> So-called flow injection analysis, in which a fixed amount of sample is injected into a mobile phase made of a solvent or the like and analyzed by flowing it, has recently become popular. Figure 2 shows
FIG. 1 is a diagram illustrating a conventional configuration of an electrochemical detector widely used in such flow injection analysis. In this figure, l has an inlet port 1a and an outlet port 1b at both ends.
The first block is provided with a measurement chamber 1c leading to the
An indicator electrode (or an indicator electrode and a counter electrode) 2 is arranged so as to be in contact with the liquid in the measurement chamber 1c. Also, 3 is the introduction port 3
This is a second block provided with a measurement chamber 3c that communicates with a and an outlet 3b, and a reference electrode 4 is disposed so as to be immersed in the liquid in the measurement chamber 3c. A pipe 5 connects the outlet 1b and the inlet 3a, and the fluid to be measured is introduced from the inlet 1a as shown by the arrow, and is discharged from the outlet 3b via the pipe 5 and the like. The reference electrode 4 and indicator electrode 2 are electrically connected to a polarographic device 6 to polarographically measure the redox substance concentration within the measurement chamber.

However, in the above conventional example, since the dead volume 1 (dead volume) in the measurement chamber IC and the measurement chamber 3c is large, the liquid to be measured introduced as a plug flow from the inlet 1a of the first block 1 The sample also often became a diffuse flow (broad flow) by the time it reached the outlet port 1b of the second block.

Therefore, when attempting to measure the liquid to be measured by connecting a detector such as a differential refractometer to the outlet 1b,
This method has the disadvantage that accurate measurement values cannot be obtained due to the tealing phenomenon of the measured component peaks.

In addition, contamination of the liquid to be measured is likely to occur within the dead zone 1A, which ultimately causes a large error in the measured values of the polarographic device.

Furthermore, in order to avoid the presence of air bubbles in the measurement chamber lc and giving noise to the measured values, when the outlet 3b applies pressure (back pressure), the air bubbles in the measurement chamber 3c of the second block 3 There was also a drawback that the measurement liquid flows back into the reference electrode 4 through the liquid junction of the reference electrode 4, significantly shortening the life of the reference electrode 4. Moreover,
In a state where such a backflow phenomenon occurs, the internal liquid that is supposed to be supplied from the reference electrode 4 through the liquid junction (not shown) into the measuring chamber 3C also becomes difficult to flow out, and the polarographic device 6
There was also a drawback that the reference potential at was also unstable.

<Problems to be Solved by the Invention> The present invention has been made in view of the drawbacks of the conventional examples, and its purpose is to prevent the generation of bubbles in the measurement chamber and to prevent the sample in the liquid to be measured from dispersing. The object of the present invention is to provide such an electrochemical detector.

Means for Solving the Problems> A feature of the present invention that solves the above problems is that in an electrochemical detector, a pressurizing part having a through hole with a small inner diameter is sandwiched between an electrode part and a reference part. The structure is such that a pressure loss of the liquid to be measured occurs in the pressurizing section.

<Example> Hereinafter, the present invention will be explained in detail using the drawings. 1st
The figure is an explanatory diagram of the configuration of an embodiment of the present invention. In the figure, the same symbols as in FIG. 2 are used with the same meanings, and the explanation here will be omitted. Further, 2a is, for example, a doughnut-shaped indicator electrode with an inner diameter of 0.5 mm, 2'a is an indicator electrode contact whose one end is attached to the indicator electrode 2a, 2b is a donut-shaped counter electrode, and 2
4' b is a counter electrode contact whose one end is attached to the counter electrode 2b;
is a reference electrode contact whose one end is attached to the reference electrode 4, 7 is a block made of a metal material (StJS 316, etc.), 8a is a connector that connects the introduction pipe 9a to the block 7 in a liquid-tight structure, and 8b is a lead-out. The connectors 1oa=IOd for connecting the pipe 9b to the block 7 in a liquid-tight structure each have a donut-shaped spacer made of, for example, a fluorine-based resin;
11 is a pressurizing section made of, for example, a fluorine-based resin, having substantially conical lead-out holes IIa, Ilb at both ends and a through hole 11c with a small diameter (for example, O, 15 mm) inside; 8a, 8b;
By screwing together the block 7 and the connector 8a,
, spacer 10a, indicator electrode 2a, spacer 10b, counter electrode 2b, spacer 10C1 pressurizing part 11, liquid 18 part 12,
The spacer 10d1 and the connector 8b are coupled in a liquid-tight structure to form the internal flow path of the embodiment of the present invention. still,
The diameter of the through hole 11c of the pressurizing part 11 is, for example, O,1.
If you use one with a length of 5 mm and a total length of 4 cm, for example, will it be covered? When the flow rate of m constant liquid is 1ml/Hin, pressurizing part 11
At about 0.5 g/a/ pressure loss occurs, and 2 ml1/
min.

A pressure loss of approximately 1.0 kg/ayl'' is generated in the molten metal.The inner diameter of the introduction pipe 9b is selected to be as large as possible in order to reduce the fluid resistance on the outlet side.

In the embodiment of the present invention configured as described above, when the liquid to be measured is introduced from the introduction pipe 9a, it is guided into the pressurizing part 11 via the indicator electrode 2a and the counter electrode 2bt-, and then the liquid junction 1 via the section 12 and the outlet pipe 9b.
ノ [to be served. In addition, the inner diameter of the pressurizing part 11 is significantly smaller than the inner diameter of the indicator electrode 2a and the counter electrode 2b, which causes piping resistance, so the liquid to be measured passing through the indicator electrode 2a and the counter electrode 2b is pressurized, and the liquid to be measured passes through the indicator electrode 2a and the counter electrode 2b. Air bubbles are less likely to form inside. Moreover, since the inner diameter of the liquid 18 section 12 is larger than the inner diameter of the pressurizing section 11, the pressure of the liquid to be measured passing through the liquid 18 section 12 is reduced, and the pressure of the liquid to be measured passing through the liquid junction section 12 is applied to the internal liquid 13. A stable reference potential can be obtained without any backflow of the measurement liquid. Furthermore, since there is almost no dead volume in the internal flow path of the embodiment of the present invention, there is no contamination of the liquid to be measured, and plug flow of the liquid to be measured introduced from the introduction pipe 9a is prevented. ) is directly led to the lead-out pipe 9b, so even if a differential refractometer or the like is connected to the lead-out pipe 9b, the liquid to be measured can be accurately measured without causing the tealing phenomenon of the measured component peak. In this state, the redox substance concentration in the liquid to be measured is polarographically detected by the indicator electrode 2a, counter electrode 2b, and reference electrode 4. Note that the present invention is not limited to the above-described embodiments, and can be modified in various ways. For example, an ion exchange membrane tube may be used as the liquid junction 12, or the counter electrode 2b and spacer IOc may be removed to form two electrodes. It is also possible to use a method.

<Effects of the Invention> According to the present invention as described in detail above, the indicator electrode 2a
Since the configuration is such that the pressurizing part 11 is provided between the counter electrode 2b and the reference electrode 4 to cause a pressure loss, the drawbacks of the conventional example described in #I are eliminated at once as described above, and air bubbles in the measurement chamber are eliminated. An electrochemical detector that can prevent this from occurring and does not disturb the plug flow of the liquid to be measured is realized.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the configuration of a conventional example. 2a... Indicator electrode, 2b... Counter electrode, 4... Reference electrode,
6...Polarographic device, 7...Block, IO
a~IOd...Spacer, 11...Pressure part, 12.
...Liquid junction, 13...Internal liquid.

Claims (4)

[Claims] (1) An electrode part consisting of an indicator electrode and a counter electrode and a reference part having a reference electrode are disposed in a flowing liquid to be measured, and an electric current is used to polarographically measure the concentration of redox substances in the liquid to be measured. A chemical detector, characterized in that a pressurizing section having a through hole with a small inner diameter is sandwiched between the electrode section and the reference section, and the pressurizing section is configured to cause a pressure loss in the liquid to be measured. chemical detector. (2) The electrochemical detector according to claim (1), wherein the pressurizing section is made of a fluorine-based resin material. (3) The electrochemical detector according to claim (1) or (2), wherein the electrode portion comprises an indicator electrode and a counter electrode. (4) Claim No. (1) in which the electrode portion is an indicator electrode.
The electrochemical detector according to item (2) or item (2).