JPH0330851Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a redox current measuring device using a polarographic three-electrode method.

Conventionally, as shown in FIG. 1, this type of apparatus has been used, for example, in which an anode, a cathode, and a comparison electrode d are immersed in a tank a containing a sample solution and an electrolyte. However, with this device, the Ag ions generated at the reference electrode d have an adverse effect on the nearby anode b, resulting in a decrease in sensitivity, and the configuration of the device necessitates intermittent measurements, making it unsuitable for laboratory use. In any case, it was unsuitable for industrial use.

The present invention aims to eliminate such conventional drawbacks. An embodiment of the present invention will be described below with reference to the drawings. In Figure 2, 1 is electrolyte 2
(for example, a Kcl solution), in which a hollow glass tube 3 is supported in the electrolyte 2.
A cathode 4 made of Pt, a support tube 5 made of glass,
A liquid junction part 6 made of ceramic or the like, a Kcl internal liquid 7, an Ag-Agcl inner electrode 8, a reference electrode 10 made of an Ag lead wire 9, etc. are immersed in it.The cathode and reference electrode are an integrated composite. Electrodes may also be used. Next, 11 is the lid 1 of the tank 1.
The electrolyte replenishment port 13 provided in the tank 1
One end of the tube is connected to a communication port 14 provided at the bottom of the tube, and the other end is connected to a porous plastic (eg, polypropylene, polyethylene, nylon) via a plastic holding member 15, as shown in FIG. Or porous ceramic rod 1
6 is retained.

A Pt wire constituting an anode 17 is wound around the outer periphery of this porous plastic rod 16.

The cathode 4, comparison electrode 10, and anode 7 are connected to an amplifying section 20 via lead wires 18, 9, and 19, respectively. Next, 21 is a plastic block constituting a sample cell, which has a sample inlet 22 at the bottom and a sample outlet 23 at the side, and as shown in FIG.
The anode 17 and the porous plastic rod 16 are disposed within the sample cell 21 and are configured to come into contact with the sample introduced into the sample cell 21.

Therefore, the detector has an anode 17, a cathode 4
The anode 17 is composed of three electrodes: and a comparison electrode 10, and a constant potential with reference to the comparison electrode 10 is applied to the anode 17. The electrolytic solution gradually flows out from the porous portion of the porous plastic rod 16, maintaining electrical continuity between the anode 17, cathode 4, and comparison electrode 10.

Now, hydrazine (N ₂ H ₄ ) (an example of a measurement target)
When sample water containing
It is oxidized as follows.

N ₂ H ₄ +4OH ^- →N ₂ +4H ₂ O+2e On the other hand, the same amount of current flows at the cathode, and the following reaction occurs.

1/2O ₂ +H ₂ O+2e→2OH ^- or 2H ⁺ +2e→H ₂ Therefore, a current proportional to the hydrazine concentration will flow between the anode 17 and the cathode 4, and the hydrazine concentration can be measured from this current value. It will be done.

As described above, in the present invention, a cathode and a reference electrode are immersed in an electrolyte in an electrolyte bath, and a porous member is held at the other end of a tube whose one end is connected to the communication port of the electrolyte bath. An anode is attached to this porous member to electrically conduct the anode, cathode, and reference electrode, and the porous member and anode are placed in a sample cell separate from the electrolyte bath. It has the following effects.

The reference electrode and anode are not immersed in the same tank as in the conventional device, but are separated by a tube.
Ag ions generated at the reference electrode rarely reach the anode;
This prevents the harmful effects of ion adhesion and allows measurements with high sensitivity at all times.

Since the electrolyte bath and the sample cell are separated, continuous measurements can be easily performed by continuously flowing the sample into the sample cell in small amounts, and
Consumption of electrolyte is also low. Therefore, it has also become possible to industrialize a redox current measuring device using the polarographic three-electrode method.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional example, FIG. 2 is an overall configuration diagram showing an embodiment of the present invention, and FIG. 3 is a longitudinal cross-sectional view of the main part of the same. 1... Electrolyte tank, 2... Electrolyte, 4... Cathode, 10... Reference electrode, 13... Tube, 14
... Communication port, 16 ... Porous member, 17 ... Anode, 21 ... Sample cell.

Claims (1)

[Scope of utility model registration request] The cathode and reference electrode are immersed in an electrolyte in an electrolyte tank, one end of which is connected to the communication port of the electrolyte tank, and a porous member is held at the other end of the tube, and the anode is attached to this porous member. The polarographic three-electrode method is characterized in that the anode, cathode, and reference electrode are electrically connected to each other, and the porous member and the anode are placed in a sample cell provided separately from the electrolyte bath. Redox current measuring device.