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Topic: Pen pH meter care before storage.  (Read 3836 times)

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Offline xchcui

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Pen pH meter care before storage.
« on: November 26, 2019, 09:25:38 AM »
Hi.

Due to lack of explanation on google about how this specific type of ph meter works(i mean scientific explanation)and poor manual.
I have some question about this pen ph meter type.
First of all,Is the part that marks with red arrow in the attached photo refer to the reference electrode?
2)Does this type of ph meter also leak electrolyte(or something)into the tested solution during its operation?
3)Regard to the manual(second photo)"OPERATION"part 6-7 sections it says"after finished,clear with D/W and replace the cap".I understand that after i finish to make measurementand before i put it in storage,i need to stir/clean the electrode bulb in distilled water solution and replace the protective cap.But do i need to dry the glass electrode from distilled water residue with tissue(or something)before i replace the protective cap or after i stir/clean the glass electrode in distilled water solution i just replace the cap without touching or drying the electrode?

Thanks.

Offline Borek

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Re: Pen pH meter care before storage.
« Reply #1 on: November 26, 2019, 10:34:47 AM »
Due to lack of explanation on google about how this specific type of ph meter works

In general - exactly the same way every other pH meter does. Many details at http://www.ph-meter.info

Quote
First of all,Is the part that marks with red arrow in the attached photo refer to the reference electrode?

Reference electrode is somewhere behind the junction, that's for sure, but where it is - no idea. Somewhere inside.

Quote
Does this type of ph meter also leak electrolyte(or something)into the tested solution during its operation?

A bit. Typical amounts are way too low to matter, unless you are dealing with some very specific, high purity solutions. But then, you shouldn't use a cheap pen pH meter.

Quote
Regard to the manual(second photo)"OPERATION"part 6-7 sections it says"after finished,clear with D/W and replace the cap".I understand that after i finish to make measurementand before i put it in storage,i need to stir/clean the electrode bulb in distilled water solution and replace the protective cap.But do i need to dry the glass electrode from distilled water residue with tissue(or something)before i replace the protective cap or after i stir/clean the glass electrode in distilled water solution i just replace the cap without touching or drying the electrode?

Don't dry the electrode. Actually leaving a bit of excess water should be a good idea.
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Offline xchcui

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Re: Pen pH meter care before storage.
« Reply #2 on: November 26, 2019, 12:54:17 PM »

Reference electrode is somewhere behind the junction, that's for sure, but where it is - no idea. Somewhere inside.

So,what is this round small part?

Don't dry the electrode. Actually leaving a bit of excess water should be a good idea.
This is the reason why i thought that this ph meter operate in different way.In the manual(not at the one i attached)it says clearly to dry the electrode before replace the cap and it doesn't say anything about store the electrode in storage solution or wet.This instruction was strange,since i read that the glass electrode must be hydrated,while dry electrode won't operate correctly,so i thought it operate in different way(new technology).May you have any idea why it says to dry it?

Offline Borek

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Re: Pen pH meter care before storage.
« Reply #3 on: November 26, 2019, 03:00:01 PM »
So,what is this round small part?

Junction - wick or a glass frit.

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This is the reason why i thought that this ph meter operate in different way.In the manual(not at the one i attached)it says clearly to dry the electrode before replace the cap and it doesn't say anything about store the electrode in storage solution or wet.This instruction was strange,since i read that the glass electrode must be hydrated,while dry electrode won't operate correctly,so i thought it operate in different way(new technology).

The only other technology I am aware of are ISFET electrodes. I can be wrong but last time I checked they were far from being cheap and popular.

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May you have any idea why it says to dry it?

No.
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Offline xchcui

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Re: Pen pH meter care before storage.
« Reply #4 on: November 27, 2019, 08:36:29 AM »
I attached(below)a dismantled pocket ph meter.Can it help in something to answer my questions?
Also,shouldn't the reference electrode that can be seen in the photo,as only a wire,should be cover with a casing and electrolyte?it looks different from ordinary ph meter.

Offline Borek

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Re: Pen pH meter care before storage.
« Reply #5 on: November 27, 2019, 10:23:28 AM »
I wonder if the wire you marked as a reference is not Ag covered with AgCl. If so, it had to be in a small chamber filled with chloride solution, and that would make perfect sense.

Or, it could be just a contact and the reference itself is built into the cap and covered with a glass frit.

How does the removed cap looks like from the inside? How was the wire attached/put into contact?

pH electrode itself looks like a more or less standard glass electrode.
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Offline xchcui

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Re: Pen pH meter care before storage.
« Reply #6 on: November 27, 2019, 11:21:09 AM »
I guess that i won't get a reliable answer,since from your answer,i see that you don't familiar with that type of ph meter.I did my best by sending a dismantle ph meter and also the manual,but if(with all my attachment)it doesn't help,i guess i leave it.
Anyway thanks alot for trying to help and for your replies :)
BTW,the remove cap has nothing special inside.

Offline gedftsnd

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Re: Pen pH meter care before storage.
« Reply #7 on: January 20, 2020, 09:22:35 AM »
i would probably invest in a better pH meter

Offline lucas.paula

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Re: Pen pH meter care before storage.
« Reply #8 on: June 06, 2021, 12:30:21 PM »
Perhaps this information is coming too late, even so:

This type of ph meter does not have a combined electrode. Thus, there are two separate electrodes on it: the working electrode (the glass sphere) which is with an Ag/AgCl wire filled with saturated KCl solution, concentration: 3M). And also the reference electrode which is exactly the one you marked in the figure, indicating it with a red arrow.

The reference electrode in this type of pH meter is a silver wire immersed in a POTASSIUM CHLORIDE GEL (3M KCl solution and 1 or 2% agarose). You can see that there is a little gel in which this thread was soaked. To avoid the passage of ions, what comes in contact with the sample to be analyzed is this small white "tube", which I don't know what would be the material of its composition.

It is difficult to extend the life of these electrodes, and soaking them in KCl solution can help. But they "say" that the gel in which the reference electrode is immersed lasts about 6 months to 1 year.

*Say: https://d163axztg8am2h.cloudfront.net/static/doc/1b/eb/282870e4b6bf7734d112d04a78bd.pdf

An illustration of a pair of electrodes of this type (those that are not matched) can be seen at: https://www.globalspec.com/learnmore/sensors_transducers_detectors/analytical_sensors/ph_orp_electrodes

And congratulations for the photos of the equipment, they were very good.

3 important tips that never appear on the web about using these devices:

1. In addition to the obvious problem of validity of electrodes, these equipments can give problems due to adhesion of organic material on the surface of the glass. In this case, you can leave them for 24 hours immersed in a 3% hydrogen peroxide solution (10 volumes), it may be that this will "resurrect" the equipment.

2. Another idiotic detail, but very common is that when the batteries are low they can indicate incorrect values, it should be checked before discarding the use of these equipment.

3. These devices are not waterproof, but the problem is much bigger than that - I always see that there is permeation of the solution into the circuit: that is, if you use it frequently, within 1 year (2 at most) most of the electronic components will be corroded.

Sorry for the incorrect English or the translation not being 100%.

Respectfully,

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