PH meter

[wineview]

When I bought my APERA PH meter, I also bought extra calibrating solution and storage solution. I just looked at the dates on the bottles and the storage solution has an expiration date of 9/13 2022. That was a surprise since I bought the package about 7 months ago. Will that date really make a difference?

 

[distancerunner]

Fresh calibration solution at the beginning of every crush.

You can mix your own. Hydrion Tri-Check Buffer Set. The capsules contain a powder that is mixed with distilled water. One kit is enough for at least three years.

 

[Rice_Guy]

Any code date is picked to give safety factor,

Specific with buffer your risk relates to exposure to air which has CO2 that will dissolve into the buffer and lower the pH or getting dirt in the bottle (never pour any back in the bottle).The word buffer means that the salt solution in your bottle has a high capacity to stay at target pH, ,,,, the salts are chosen to be in a flat region of a titration curve.

Now practically speaking; if I was in a research lab and wanted three or four place accuracy (.001 or .0001) I would be concerned. if I am a home wine maker with a target of 3.10 to 3.50 for whites or fruit, and 3.50 to 3.80 for reds I wouldn’t have any concern about using five year old buffer which has had the cap promptly replaced every time some is removed.

 

[wineview]

Any code date is picked to give safety factor,

Specific with buffer your risk relates to exposure to air which has CO2 that will dissolve into the buffer and lower the pH or getting dirt in the bottle (never pour any back in the bottle).The word buffer means that the salt solution in your bottle has a high capacity to stay at target pH, ,,,, the salts are chosen to be in a flat region of a titration curve.

Now practically speaking; if I was in a research lab and wanted three or four place accuracy (.001 or .0001) I would be concerned. if I am a home wine maker with a target of 3.10 to 3.50 for whites or fruit, and 3.50 to 3.80 for reds I wouldn’t have any concern about using five year old buffer which has had the cap promptly replaced every time some is removed.

It’s not the buffer solution. It’s the storage solution. And yes it has been tightly capped.

 

[Rice_Guy]

The storage solution consists of calomel salts at the same concentration as the inside of the pH probe and preservative. The purpose for this is to keep from diluting out the inside of the probe/ lose the conditioning on the thin glass membrane (bulb) such that it stops being electrically conductive. Storage solution is not especially reactive to CO2 and will last.

By the way modern gel filled probes have a small sponge wetted with storage solution. They are intended to not leak constantly into their container. ,,, It really doesn’t take much to maintain the electrical property of the glass. ,,,
! ! Do not let the glass bulb dry! ! ! ,,, if it does you can usually recondition the electrical property by storing/ hydrating the thin glass bulb in storage solution.
What else, ,,, traditional glass bulbs are fragile and should not be touched.

 

[wineview]

The storage solution consists of calomel salts at the same concentration as the inside of the pH probe and preservative. The purpose for this is to keep from diluting out the inside of the probe/ lose the conditioning on the thin glass membrane (bulb) such that it stops being electrically conductive. Storage solution is not especially reactive to CO2 and will last.

By the way modern gel filled probes have a small sponge wetted with storage solution. They are intended to not leak constantly into their container. ,,, It really doesn’t take much to maintain the electrical property of the glass. ,,,
! ! Do not let the glass bulb dry! ! ! ,,, if it does you can usually recondition the electrical property by storing/ hydrating the thin glass bulb in storage solution.
What else, ,,, traditional glass bulbs are fragile and should not be touched.

I would never let the bulb dry out. It is stored in the supplied small cup with solution in it at all times. Also it would be difficult to touch the bulb. This model has it pretty well protected.

 

[BarrelMonkey]

Any code date is picked to give safety factor,

Specific with buffer your risk relates to exposure to air which has CO2 that will dissolve into the buffer and lower the pH or getting dirt in the bottle (never pour any back in the bottle).The word buffer means that the salt solution in your bottle has a high capacity to stay at target pH, ,,,, the salts are chosen to be in a flat region of a titration curve.

Now practically speaking; if I was in a research lab and wanted three or four place accuracy (.001 or .0001) I would be concerned. if I am a home wine maker with a target of 3.10 to 3.50 for whites or fruit, and 3.50 to 3.80 for reds I wouldn’t have any concern about using five year old buffer which has had the cap promptly replaced every time some is removed.

I replace my pH standards every year - I agree that dissolved CO2 doesn't make a huge difference, particularly if I'm only looking to target a broad range (eg 3.5-3.8). But while 3.70 and 3.71 are the same to me (and to my probe/meter, given its error!), I do want to know the difference between 3.70 and 3.80. I only buy ~250mL at a time, so after a year of measurements I'm running low anyway.

I just ordered new standards so when they arrive I'll compare new vs old and report back.

 

[wineview]

I replace my pH standards every year - I agree that dissolved CO2 doesn't make a huge difference, particularly if I'm only looking to target a broad range (eg 3.5-3.8). But while 3.70 and 3.71 are the same to me (and to my probe/meter, given its error!), I do want to know the difference between 3.70 and 3.80. I only buy ~250mL at a time, so after a year of measurements I'm running low anyway.

I just ordered new standards so when they arrive I'll compare new vs old and report back.

Sounds good. I'll look for your report.

 

[Daboyleroy]

What should I store my pH electrode in?

Proper storage of your electrode is important to maintain hydrated pH glass.

Using a storage solution, such as the HI70300L storage solution helps to maintain the reference electrolyte concentration. This is important because the reference electrolyte generates a known mV potential, without this, the electrode will not work properly.

Storing a pH electrode in water affects the reference electrolyte concentration, and it also damages the pH glass.

Buffers can also affect the reference electrolyte concentration if you store your pH electrode in them.

Warning: Refresh your electrolyte inside your pH electrode, and then allow the electrode to rehydrate in storage solution for at least an hour (if not several) before attempting to recalibrate the electrode.


What should I store my pH electrode in?

 

[BarrelMonkey]

Sounds good. I'll look for your report.

I opened my 2022 pH standards today so I thought I'd report back here.

Materials and methods:
I have a MW102 pH meter, purchased almost exactly a year ago and still with the original probe. pH standards (4.01 and 7.01) were also from Milwaukee. Last year's standards were opened in September 2021, this year's were opened today (8/17/22). All are stored at room temperature. The pH probe is stored in Milwaukee's electrode storage solution when not in use.

I calibrated the meter according to manufacturer's instructions. I always rinse the probe in distilled water between uses, and briefly rinse in a separate vial of pH standard before using the actual reference solution. Samples/standards were gently agitated with the probe while the reading stabilized.

Results:
Both pH 4 and pH 7 gave identical results for the 2021 and 2022 reference standards, within 0.01 pH units - I retested the new (2022) standards after calibration for confirmation.

Nominal calibration pH values: 4.01, 7.01
2021: 4.00, 7.00
2022: 4.01, 7.00

Conclusion:
Based on this single evaluation using my equipment and reagents, I don't think it's necessary to change reference solutions annually (though it doesn't do any harm!)

 

[wineview]

I opened my 2022 pH standards today so I thought I'd report back here.

Materials and methods:
I have a MW102 pH meter, purchased almost exactly a year ago and still with the original probe. pH standards (4.01 and 7.01) were also from Milwaukee. Last year's standards were opened in September 2021, this year's were opened today (8/17/22). All are stored at room temperature. The pH probe is stored in Milwaukee's electrode storage solution when not in use.

I calibrated the meter according to manufacturer's instructions. I always rinse the probe in distilled water between uses, and briefly rinse in a separate vial of pH standard before using the actual reference solution. Samples/standards were gently agitated with the probe while the reading stabilized.

Results:
Both pH 4 and pH 7 gave identical results for the 2021 and 2022 reference standards, within 0.01 pH units - I retested the new (2022) standards after calibration for confirmation.

Nominal calibration pH values: 4.01, 7.01
2021: 4.00, 7.00
2022: 4.01, 7.00

Conclusion:
Based on this single evaluation using my equipment and reagents, I don't think it's necessary to change reference solutions annually (though it doesn't do any harm!)

Thank you. Very good information.

 

[4score]

Just thought I'd share my latest pH meter experience. I've had many different ones, but finally found one that is reasonably priced and seems to do a great job. I ordered "APERA INSTRUMENTS AI209 Value Series PH20 Waterproof pH Tester Kit" on Amazon for ~$50. It comes in a nice little hard plastic case. Inside the case, there are foam cutouts to securely hold the meter and buffering solutions (4.0 & 7.0). I asked the company for their recommendation for storing after use and they said, "Please do not fill the probe cap with pure water or tap water. Soaking the pH electrode in water will reduce the sensitivity of the pH glass membrane, which will lead to the premature failure, and eventually replacement of the electrode very soon. If this happens, immediately soak the pH probe Apera 3M KCL soaking solution overnight, then recalibrate it before using. Pure water is only for rinsing the probe.

The following is the correct way of storing your PH20 electrode:

Under regular usage (daily or weekly use), just make sure the probe cap is wet, and tightly close the cap with the red O-ring.

For long-term storage (you are not going to use the product for a while), add Apera 3M KCL soaking solution (AI1107) or pH 4.00 buffer solution to the Fill line in the probe cap and store the probe in it. Close on the probe cap tightly with the red O-ring.