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Ph buffer solution??

11 years ago

I just ordered a pH meter for measuring the acid/alkaline condition for wine. It is suggested that I also order "buffer solution."

Please educate me as to why this is necessary, and which buffer solution I need. It comes in different strengths apparently or for different measurements.

Bejay

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Comments (5)

bejay9_10
Original Author
11 years ago
OK - since I just ordered the meter, I also went back and ordered the buffers. They come with instructions, so maybe I can get on with my new "making wine education" - thanks anyway.

Since I'm presently in between batches, I can't tell you yet what their significance is, but as soon as I become expert, will share with you - that is, if you really want to know.

Bejay
chas045
9 years ago
I see that this is a slow forum, but this is a good question for some that was never answered. A pH meter doesn't actually read acidity, it just reads a voltage or a current that is generated between two probes placed in a liquid. Usually, these two probes are combined into one unit. Less sensitive/accurate probes may have some plastic protective casings but some are Very breakable And expensive!

The situation is slightly like trying to read a glass tube thermometer that has slipped in its housing or where the markings have rubbed off. You need the pH buffers, they are usually called 'standards', as reference points to tell you (or the meter) what the voltage represents in pH units. You need at least two different buffers to tell the meter what two voltages refer to. For example you could set the probe in a pH 4.0 buffer and adjust the meter to 4 and then set the probe in a pH 7.0 buffer and adjust the slope; the rate of change in reading, so that the meter now reads 7. You then assume that the probe responds linearly between 4 and 7 which is probably true for a decent probe.

The standards are called buffers because they contain a set of chemicals that will maintain its pH even if small amounts of different pH stuff gets mixed in; air containing carbon dioxide which will make carbonic acid when dissolved in the liquid, for example.

You continue to need the buffers because the probe may or will get clogged up some or a lot, and its response will change. The settings will need to be adjusted. And finally, the buffers will eventually change too and depending on accuracy needed, require replacement.
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A couple points that might be of interest. Temperature will affect readings. Since your units don't appear to have a temperature adjustment try to take all your readings at or near room temperature. Even your calibration fluids should be warmed to room temp if you store them refrigerated. Since these solutions are buffered it takes alot of contamination to change their pH. pH elotrodes rely on ion transfer accross a membrane. If that membrane material becomes blocked you may need to rejuvinate the electrode. There are various recommendations on the web but basically you need to soak the electrode in a stronger acid for a short interval to digest the gunk from the porous membrane. This method works about 50% of the time. If the readings frequently "Drift" or are slow to reach the end reading you should consider rejuvination. Storing the electrodes dry is one of biggest problems. I never used salt soln but the tip should be kept from drying by either keeping in a tap water vessel or putting tap water in the cover cap before reinserting it onto the electrode tip. Some units are junk out of the box. We spent a $400 for a stainless steel unit from IQ Scientific Instr that never would give reliable readings. If you check out a source like colepalmer.com you see that they carry hundreds of electrodes for various applications. If you want better results than you can get with litmus paper then you might want to look into a credible unit.
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My last post about the plaster of paris is not some kind of hooey that I invented. When I was a kid way back in the 1960's all of the pet shops and variety stores, that sold fish keeping supplies, sold a product made of plaster of paris to keep in your fishbowl. They were called various names, like Water Conditioner, Molly Blocks,etc.. Some were called Weekend Feeders, with little pieces of fishfood in them. They were mostly molded like little seashells to be decorative. The main thing they did was buffer the ph of the water/ raise the alkalinity of the water. I never understood what they really did for the water until years later when I started keeping salt water and african rift lake fish. They all require high and stable pH water, and it was maintained by using alkaline gravel in the tanks (kind of like adding lime to your garden soil). This only seemed to work if you did a lot of water changes, which are still very important, but I remembered those little blocks of POP and made one for my aquarium. Suddenly the pH was very stable, and I have used them ever since.These work so well because the POP is less stable in water(disolves faster than the gravel). My freinds that have pet shops use them in the filter vats on their systems to. Garbird
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bejay9_10
Original Author
9 years ago
I'm sorry to be so late in replying to your nice msg. It is appreciated, I assure you.

I'm a novice wine maker - and now have made 3 batches of lime wine (a tree that produces abundantly in the winter months here in California).

Your answer helps to clear up the questions I have. Since lime juice is very acidic, it was necessary for me to learn more about the use of the meter. I hope I read your post OK. I note also, that I need to be very careful in the use of the different buffers, so they don't become contaminated.

Incidentally, I'm doing quite well with "Skeeter's Pee" as it is referred to. I found the recipe on the "net" and have learned a lot, especially because we have so much fruit.

I have planted some Chardonnay grapes, and they are looking great. Hopefully, in time I will be able to get some of my favorite wine - made at home.

bejay
chas045
7 years ago
Hi bejay: I hope things are working out for you. I don't recall why I looked at the Wine forum and saw your post. As you can now see, I don't browse here. Thanks for your actually very quick response. Sounds like you have things under control. I doubt that wine requires really accurate pH readings, but yes, you shouldn't contaminate the buffer solutions with the wine or the other buffer solution. Normally, you would keep a squirt bottle of water next to the pH meter to rinse the probes into a spare beaker or bowl or sink etc, before changing from one buffer or wine sample to another.
flatwoods_farm
7 years ago
You need to store the pH meter "wet". Storage solution is used for this as allowing the probe to dry out can compromise the unit.

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