pH Buffer Solutions

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Tobor_8thMan

Tobor_8thMan

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While looking thru the AIH website during their sale, I considered purchasing some buffer solution for my pH meter. Noticed the following in the Q&A

"Q: I'm new to ph testing. Do I need to always calibrate my meter using both the 4.0 and 7.0 buffer solutions or can just use one to accurately calibrate?
Asked by: NA Ben - 3/20/2017

A: You can use one or the other, depending on which range your looking to test
Was this answer helpful?

Answer provided by: Aaron (3/21/2017)"

Gets me thinking. If we're testing our mash pH, why do we need to calibrate at both 4 and 7?

Thanks.
 
Two points, ideally two points that bracket the expected ranges to be measured, are needed to compute the electrode slope. With a single point calibration, measurements will be less accurate the further you get from the calibration point.
 
Follow up question... some bottles of buffer solution that they are only good for a certain amount of time unopened and a certain amount of time opened. What if they are stored in the fridge (37F)? Does the buffer solution remain viable if stored cold? If so, how cold and how long?

Thanks.
 
Interesting question for which I have no answers to offer. But I wonder if the shelf life difference between "room" and "fridge" temps would be significant given there's likely a decent amount of CO2 ingress through what appears to be an LDPE bottle at either temperature...

Cheers!

[edited - meant CO2 because that lowers pH]
 
Since it's a chemical reaction with CO2 that makes buffers "expire," I would think storing buffers cold would extend their shelf life, but I have no idea by how much.
 
Tobor_8thMan said:
Was this answer helpful?
Click to expand...
That's a definite NO. I wish some people would bother to actually understand the question before answering...

As to the cold storage of solutions, on the one hand this slows down reactions with atmospheric contaminants such as CO2, on the other hand lower temperatures increase the solubility and therefore the concentration of said contaminants so it's really hard to give a definitive answer. To be on the safe side I'd go with no difference other than opened/unopened.
 
Tobor_8thMan said:
Gets me thinking. If we're testing our mash pH, why do we need to calibrate at both 4 and 7?
Click to expand...

Well, we are mashing at about 5.5.... which is smack dab in the middle of 4 and 7. I know if I only calibrated with just one of the two solutions, my pH reading would be inaccurate. More data leads to better accuracy.

AND... I think you all will be interested in this, from a veteran chemist at a nuclear power plant who writes procedures for this stuff:

https://www.homebrewersassociation.org/forum/index.php?topic=34543.msg435705#msg435705
 
Last edited:
VikeMan said:
Two points, ideally two points that bracket the expected ranges to be measured, are needed to compute the electrode slope. With a single point calibration, measurements will be less accurate the further you get from the calibration point.
Click to expand...

^^This^^

And don't forget to properly clean the probe after use (get some cleaner to go along with the 4.0 & 7.0 buffers), and stop it with the a few drops of buffer solution in the probe cap to keep it from drying out.
 
Thanks. Yes. I have cleaning and storage solution. What about the life of these 2 items (cleaning and storage solution).

I need to find some of the dark brown medical bottles we used to have when I was young to store the buffer solutions. Never thought about these types of brown medical bottles until now. I learned something new today. Thanks!
 
Jtvann said:


Shameless plug for a video I just made on pH Calibration.
Click to expand...


Wow, this video is age restricted. Makes me feel as if I'm purchasing beer locally and a teenager is asking me for ID. I ask them "How much is 2020 - (my birth year)"? I get a dumbfounded look as their cell phone is not nearby.

Also, must have a YouTube account and sign in to view. Um... no thanks.
 
Tobor_8thMan said:
Wow, this video is age restricted. Makes me feel as if I'm purchasing beer locally and a teenager is asking me for ID. I ask them "How much is 2020 - (my birth year)"? I get a dumbfounded look as their cell phone is not nearby.

Also, must have a YouTube account and sign in to view. Um... no thanks.
Click to expand...

Oh well
 
When one puts a video up on Youtube it has to be declared "for kids" or not. And all of my brewing-related videos are "not for kids".
But that's a broad declaration and unless one pushes some extra buttons they don't carry an "age restriction". None of mine do...

Cheers!
 
I am being caution in my personal life and job to not have any possible complaints come back on a video that I posted. Beer (wort) is tested in the video and id rather click a simple button than answer any questions. Video asked if it was “for kids” and I said no. Age restriction was automatic for mine.

I wouldn’t mind posting the video here, but don’t know how.
 
Jtvann said:
I am being caution in my personal life and job to not have any possible complaints come back on a video that I posted. Beer (wort) is tested in the video and id rather click a simple button than answer any questions. Video asked if it was “for kids” and I said no. Age restriction was automatic for mine.

I wouldn’t mind posting the video here, but don’t know how.
Click to expand...

Or, please directly send to me in a private conversation as I'd welcome.

I haven't been 21... well I don't remember how long...
 
Tobor_8thMan said:
Or, please directly send to me in a private conversation as I'd welcome.

I haven't been 21... well I don't remember how long...
Click to expand...

The file is too large to post here. It’s about a 5 minute video. If someone knows how to tell me to post it outside of YouTube I will.

Also, are you serious about the 21 thing?
 
How about allowing me to temporarily host it on my humble Youtube channel long enough for Tobor_8thman to view it?
I've already pushed it up, just need to post the URL. Let me know either way...

Cheers! :)
 
Jtvann said:
The file is too large to post here. It’s about a 5 minute video. If someone knows how to tell me to post it outside of YouTube I will.

Also, are you serious about the 21 thing?
Click to expand...

Yes, recently at a local Giant Food store. Checkout girl, we can still write "girl", asks for my ID. That's when I say to her 2020 - (my birth year) = ? She just looks at me.

I then said, OK, apparently I'm under 21, what are you doing tonight? Of course, wife behind me, didn't think this was very funny.
 
as far as the age restricted videos....i watched it, next one that came on was "Grow from your heart", talking about nutrient spiking pot plants when they're flowering.
 
dmtaylor said:
Just take the age restriction off of it. It's a good video, and has zero reason to be restricted.
Click to expand...

Thanks for the advice. It’s related to beer. We’re all 21 and above here, supposedly. You made an account to post here on homebrewtalk. If you want to watch the video, make an account on YouTube and confirm you’re 21.
 
Tobor_8thMan said:
OK, any storage concerns about the rinse solution and the storage solution?
Click to expand...

Not that I'm aware of. I just store them (cleaner, storage, 4.01 pH and 7.01 pH) in small plastic bottles, all in an overhead cabinet next to my pH meter and refractometer. Also, if you can't find any storage solution, supposedly 4.01 pH buffer is an adequate storage media to keep the bulb hydrated.
 
I suspect degradation of buffers is due mostly to atmospheric gas contamination via ingress through the plastic bottles, though I suppose I could be wrong and there's something intrinsically unstable in buffer solutions.

There's a "rinse solution"? I just use my RO faucet after every reading...

Cheers!
 
Brooothru said:
Also, if you can't find any storage solution, supposedly 4.01 pH buffer is an adequate storage media to keep the bulb hydrated.
Click to expand...

Hmm. In a pinch, maybe, but my understanding is that 4.01 buffer isn't a good osmotic balance for the probe's electrolyte, so it would deplete the electrolyte over time.
 
VikeMan said:
Hmm. In a pinch, maybe, but my understanding is that 4.01 buffer isn't a good osmotic balance for the probe's electrolyte, so it would deplete the electrolyte over time.
Click to expand...

My pH meter is a lesser expensive Hanna tester, probably $50 bucks or so. Clearly a hobbyist or academic grade instrument and not lab quality. Still, much better than litmus paper strips. I just reread the instructions sheet and it did indicate 4.01 pH buffer as an alternative to storage solution, but I think the operative point they were making was to keep the bulb moist. I only mentioned it because my LHBS always seems to have buffer solutions but not always storage solution or cleaner.
 
day_trippr said:
Wouldn't know either way, but most storage solutions are 3M or higher saturated KCL...
Click to expand...

So I can 'roll my own' storage solution by making a >3 mol mixture of potassium chloride and, what, distilled water? It's as simple as that?

As far as cleaning, I usually pour a shot glass full of distilled and put the pH meter in it between uses during a brew session. When done for the day, rinse with fresh distilled water and store with a capful of 4.01 buffer since I can't seem to find storage solution anywhere.
 
Brooothru said:
So I can 'roll my own' storage solution by making a >3 mol mixture of potassium chloride and, what, distilled water? It's as simple as that?

As far as cleaning, I usually pour a shot glass full of distilled and put the pH meter in it between uses during a brew session. When done for the day, rinse with fresh distilled water and store with a capful of 4.01 buffer since I can't seem to find storage solution anywhere.
Click to expand...

Amazon has it - this is the one I got:
https://www.amazon.com/gp/product/B07NXTBD8D/
 

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