JPS6269158A - Liquid film type electrode for measuring ph - Google Patents

Abstract

PURPOSE:To exactly measure an acidic region by forming an org. material contg. tri-n-octyl phosphine oxide as a response film. CONSTITUTION:A prescribed amt. of PVC resin power is first dissolved in a prescribed amt. of tetrahydrofuran to obtain a soln. A. A prescribed amt. of tri-n-octyl phosphine oxide and potassium tetraquis (p-chlorophenyl) boron are dissolved into a prescribed amt. of o-nitrophenyl octyl ether to obtain a soln. B. A soln. mixture 6 prepd. by mixing the solns. A and B is contained into a vessel 5 consisting of a material such as tetrafluoroethylene resin which is not attached by reagents. The vessel is put into a desiccator 1 to evaporate the tetrahydrofuran. The resulted film-like body is used as the response film 12 of a measuring electrode 10. The resulteted electrode 10 makes Nernst response within a 0-4 pH range and responds exactly up to 7 pH.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a liquid film type pH measuring electrode.

[Conventional technology]

Conventionally, glass electrodes have been widely used to measure the pH of solutions. This is because the glass electrode has the following advantages: ■ Has a wide pH response range; ■ Almost unaffected by other ions; ■ Hardly affected by oxidizing substances; ■ Easy to handle. This is because

[Problems to be Solved by the Invention] However, although glass electrodes have the above-mentioned excellent advantages, they also have the following drawbacks.

(Difficult to process and manufacture into a flexible shape (e.g. sheet form, fine scratching), (Difficult to directly adhere the BL response membrane to a plastic body, (C1 cracks easily, and there are problems in applying it to the human body, etc.) Yes, f
dl]・Cannot be applied to C solution containing hydroheptahydric acid, etc.

As a solution to the problems of (al~(di) mentioned above,
Recently, a liquid film type pH measurement electrode has been proposed and put into practical use, which uses an organic substance containing hydrogen ion-selective ) 'J-n-t□denruamine ([C+zHzico)N] as a response membrane.

However, the pI of the liquid film type pH measurement using an organic substance containing this tree n-dodecyl as a response membrane.
(The response range was from weakly acidic to alkaline, and it was not possible to measure the acidic region.

The present invention has been made with the above-mentioned considerations in mind, and its purpose is to provide a liquid film type pH measuring electrode that can accurately measure acidic regions.

[Means for solving problems]

The present inventors have discovered that tri-n-octylphosphine oxide has excellent response characteristics to pH, and have used an organic substance containing this tri-n-octylphosphine oxide as a response membrane for a liquid film type pH measurement electrode. That's what I did.

(Example〕 The present invention will be explained in detail below.

The responsive membrane according to the present invention contains tri-n-octylphosphine oxide (1,639 wt%), o-nitrophenyl octyl ether (65,563 wt%), potassium tetrakis (p-chlorophenyl) boron (0,016 wt%),
(32,782-t%) and polyvinyl chloride resin (32,782-t%)
).

First, the manufacturing procedure of the response membrane will be explained.

il+ Polyvinyl chloride resin (hereinafter referred to as PVC)
Weigh a predetermined amount of powder and place it in an Erlenmeyer flask with an inner stopper (3
0m/).

Shin-Etsu Chemical Co., Ltd. (■ fAT K-25
001-11 molecular weight of 2500 is suitable.

(2) By dropping a predetermined amount of tetrahydrofuran (hereinafter referred to as THF) into the Erlenmeyer flask using a volumetric pipette, the PVC dressing powder weighed in step 11 above is dissolved.

At this time, it is preferable to gently shake the Erlenmeyer flask to disperse the PVC powder as appropriate.

(3) Weigh a predetermined amount of tri-n-octylphosphine oxide.

(4) Weigh out a predetermined amount of potassium tetrakis(p-chlorophenyl)boron as an additive.

(5) Above f3+, dissolve the tri-n-octylphosphine oxide weighed in (41) and potassium tetrakis (p-chlorophenyl) boron in a predetermined amount of 〇-nitrophenyl octyl ether, and Bring to a stirred solution.

(6) Above +21. The solutions obtained at +51 were mixed to form a well-stirred mixture.

(7) Place the mixed solution obtained in (6) above in a container made of a material that is not easily affected by reagents, such as tetrafluoroethylene resin, and place the container in a desiccator! ! After 2 hours, the THF contained in the mixed solution is released once.

FIG. 1 shows an example of the apparatus used in the drying process, in which 1 is a desiccator, 2 and 3 are pipes for supplying and discharging nitrogen, respectively, and 4 is a flow rate adjustment section. 5 is above (6)
A container containing the mixed liquid 6 obtained in (for example, an inner diameter of 6
0■■, depth 3Qmm), 7 is a glass plate that closes the opening of the container 5. 8 is a filter paper interposed between the upper end of the opening of the container 5 and the glass plate 7;
Two sheets of 25mM filter paper are stacked on top of each other, and the THF contained in the liquid mixture 6 can easily come out of the container 5 through the gap between them.

Keep the inside of desiccator 1 at room temperature and supply nitrogen at 0.51 per minute.
Leave it for 48 hours while flushing at the same rate. In this case, it is desirable that the mounting surface 9 of the desiccator 1 on which the container 5 is mounted is kept horizontal.

(8) T contained in the mixture 'eLG due to (7) above
When HF is applied seven times, a film-like material F having a thickness of 0.1 to 0.3 am and a diameter of 60mm is obtained in the container 5, as shown in FIG. This film-like material F contains tri-n-octylphosphine oxide, potassium tetrakis(p-chlorophenyl)boron as an additive, and 0-nitrophenyl octyl ether as a carrier.
It is sealed in C.

(9) Since the peripheral edge of the film-like material F obtained in (8) above protrudes upward, this portion is cut off and the flat portion is made into a predetermined size (for example, 10 mm in diameter). Cut it out and use it as a response membrane.

FIG. 3 shows the main part of a liquid film type pH measuring electrode 10 incorporating the response membrane manufactured as described above, and in the figure, 11 is a plastic body. The response membrane 12 is attached to the adhesive 13 in the recessed end portion of the plastic body 11.
is fixed by. The plastic body 11
Inside is an inner pole 14.3 consisting of Heg/HegCI.
An internal liquid 15 consisting of 33M KCI and a buffer solution is sealed.

Figure 4 shows the pH of the liquid film type p++ measuring electrode lO with the above configuration.
The response characteristics are shown, with the horizontal axis representing pH and the vertical axis representing electromotive force. From this characteristic diagram, it can be seen that the liquid film type pH measurement electric scraper according to the present invention
It can be seen that O exhibits a Nernstian response in the range of pH0 to 4, and responds accurately up to p117.

〔Effect of the invention〕

As explained above, the liquid film type PL! according to the present invention! Since the measuring electrode uses an organic substance containing tri-n-octylphosphine oxide as a responsive membrane, it is possible to accurately measure the acidic region. The response membrane is a tri-
Since n-octylphosphine oxide is encapsulated in PVC along with additives and a solvent and formed as a plastic film, it can be processed into a flexible shape, eliminating the risk of breakage, etc. (We were able to resolve all of the problems with dl.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing an outline of the equipment used in the drying process when manufacturing the response membrane used in the liquid film type pH measuring electrode according to the present invention, and Fig. 2 shows the film-like body obtained by the drying process. FIG. 3 is a cross-sectional view showing a liquid film type pH measuring electrical equipment part incorporating a response membrane obtained by cutting out a film-like body, and FIG. 4 is a characteristic diagram of the above-mentioned l&membrane type pH measuring electrode. 12...Response membrane, F...Film-like body.

Claims (1)

[Claims] A liquid film type pH measurement electrode characterized in that a response membrane is made of an organic substance containing tri-n-octylphosphine oxide.