PH calibration solutions

PH calibration solutions

Post by Steve Smal » Sun, 21 Apr 2002 03:54:52



Hi folks,
quick question - I have 2 buffer solutions for calibrating my ph meter (7.00
and 4.00). These are now 16 months old. Do these solutions go _off_  over
time or are they stable?

steve

 
 
 

PH calibration solutions

Post by Dewey & Lucy Thompso » Sun, 21 Apr 2002 07:00:48


They generally do have an expiration date, but they don't drift much, I
suspect that they are fine for your needs.
Dewey


Quote:
> Hi folks,
> quick question - I have 2 buffer solutions for calibrating my ph meter
(7.00
> and 4.00). These are now 16 months old. Do these solutions go _off_  over
> time or are they stable?

> steve


 
 
 

PH calibration solutions

Post by Joe Sallust » Mon, 22 Apr 2002 06:49:04


Steve
They do go off with time, but if they are not moldy ('stuff' you did
not put in there floating around) they may still be good.

I use Hydrion capsules; you empty them in 100 ml of distilled water
and add a few drops of preservative; they last about 3 months.  Fisher
Sientific sells them, but any good chemical supply company will sell
them too.  They come from Brooklyn.
Regards
Joe

Quote:

> Hi folks,
> quick question - I have 2 buffer solutions for calibrating my ph meter (7.00
> and 4.00). These are now 16 months old. Do these solutions go _off_  over
> time or are they stable?

> steve

 
 
 

PH calibration solutions

Post by Jod » Mon, 22 Apr 2002 07:16:28


Quote:
> I have 2 buffer solutions for calibrating my ph meter (7.00
> and 4.00). These are now 16 months old. Do these solutions go _off_  over
> time or are they stable?

Steve-
I generally replace solutions and re-calibrate my ph meter three times
a year. Following harvest, just prior to bottling, and somewhere in
the middle. I can't say for certain, whether the solutions go bad, but
many labs, 'experts', etc... suggest they lose accuracy after 6
months.

I purchase Hanna sachets of buffering solution just prior to
calibrating my meter. They are one time use packs, inexpensive, and
ensure accurate calibration if you purchase them right before you need
them. You won't need to keep those huge bottles of solution on your
shelf and worry whether or not they are still accurate. Also, I
believe st. pats offers capsules that can be dissolved in a
predetermined amount of distilled water to make up a solution right
when you need it. Supposedly, these capsules have a much longer shelf
life.

Jody

 
 
 

PH calibration solutions

Post by Rex Frankli » Thu, 25 Apr 2002 04:16:21


You may make your own buffer solution by dissolving cream of tarter
(potassium bi tartrate) in distilled water  until the solution is super
saturated. That is, until there remains an un dissolved amount in the bottom
of the container. Wait until the solution clears and the clear supernatant
will be 3.45 pH over a fairly wide range of temps.

Quote:
> > I have 2 buffer solutions for calibrating my ph meter (7.00
> > and 4.00). These are now 16 months old. Do these solutions go _off_
over
> > time or are they stable?

> Steve-
> I generally replace solutions and re-calibrate my ph meter three times
> a year. Following harvest, just prior to bottling, and somewhere in
> the middle. I can't say for certain, whether the solutions go bad, but
> many labs, 'experts', etc... suggest they lose accuracy after 6
> months.

> I purchase Hanna sachets of buffering solution just prior to
> calibrating my meter. They are one time use packs, inexpensive, and
> ensure accurate calibration if you purchase them right before you need
> them. You won't need to keep those huge bottles of solution on your
> shelf and worry whether or not they are still accurate. Also, I
> believe st. pats offers capsules that can be dissolved in a
> predetermined amount of distilled water to make up a solution right
> when you need it. Supposedly, these capsules have a much longer shelf
> life.

> Jody

 
 
 

PH calibration solutions

Post by David C Breed » Thu, 25 Apr 2002 05:37:15


Quote:

>You may make your own buffer solution by dissolving cream of tarter
>(potassium bi tartrate) in distilled water  until the solution is super
>saturated. That is, until there remains an un dissolved amount in the bottom
>of the container. Wait until the solution clears and the clear supernatant
>will be 3.45 pH over a fairly wide range of temps.

Are you sure of that?  I thought that it was 3.56.

Dave
****************************************************************************

 
 
 

PH calibration solutions

Post by Rex Frankli » Thu, 25 Apr 2002 07:20:09


You are correct sir!


Quote:

> >You may make your own buffer solution by dissolving cream of tarter
> >(potassium bi tartrate) in distilled water  until the solution is super
> >saturated. That is, until there remains an un dissolved amount in the
bottom
> >of the container. Wait until the solution clears and the clear
supernatant
> >will be 3.45 pH over a fairly wide range of temps.

> Are you sure of that?  I thought that it was 3.56.

> Dave

****************************************************************************
Quote:
> Dave Breeden


 
 
 

PH calibration solutions

Post by Steve Smal » Sat, 27 Apr 2002 01:23:18


Folks - thanks for the information and suggestions. I will consider the
cream of tarter option, although I bought some at the grocery store 2 weeks
ago for a particular recipe and the little bottle cost $7+ - so it might be
cheaper to get some solutions from Hanna or elsewhere

steve

 
 
 

PH calibration solutions

Post by Joe Sallust » Sun, 28 Apr 2002 20:50:59


Steve
The Hydrion capsules are much cheaper in the long run, you need a way
to measure 100 ml of distilled water.  You can buy a calbration kit of
10 each of 4,7,10 pH capsules for about $20 US, or boxes of 50 each of
individual ones for specific pH's, I get a box of 3.00 too.  They are
accurate to 0.00 pH.

That is enough to last 2.5 years if you make a new batch up every 3
months.  Any chemical supply house should have them.  Mine come from
Fisher Scientific.
Regards
Joe

Quote:

> Folks - thanks for the information and suggestions. I will consider the
> cream of tarter option, although I bought some at the grocery store 2 weeks
> ago for a particular recipe and the little bottle cost $7+ - so it might be
> cheaper to get some solutions from Hanna or elsewhere

> steve

 
 
 

PH calibration solutions

Post by BENNET » Tue, 30 Apr 2002 00:34:15


Vinquiry, one of the leading wine labs, located in Santa Rosa, CA lists pH
buffers good for 4 months to a year. Since they are a commercial lab, I would
trust the solutions for the year if you store them in the closed container.

Bob B

 
 
 

PH calibration solutions

Post by Joe Sallust » Tue, 30 Apr 2002 20:37:19


Bob,
Just to expand on your comments; with use the lower pH ones seem to go
moldy within a few months.  As long as you don't see 'swirls' of
'stuff' in the containers I might agree with you.  I've never seen one
last a year that was opened, but as long as they aren't moldy you may
be ok.  All buffers should be tightly sealed when not in use as you
also mentioned.

I mark the date first used on mine, I'll check to see how long I get
away with next time.  So far it's never been more than 4 months. What
I do sometimes is make up a new batch and intercompare; the moldy ones
are always off.
Regards,
Joe

Quote:

> Vinquiry, one of the leading wine labs, located in Santa Rosa, CA lists pH
> buffers good for 4 months to a year. Since they are a commercial lab, I would
> trust the solutions for the year if you store them in the closed container.

> Bob B

 
 
 

PH calibration solutions

Post by David C Breed » Tue, 30 Apr 2002 21:59:56


Quote:

>Bob,
>Just to expand on your comments; with use the lower pH ones seem to go
>moldy within a few months.  As long as you don't see 'swirls' of
>'stuff' in the containers I might agree with you.  I've never seen one
>last a year that was opened, but as long as they aren't moldy you may
>be ok.  All buffers should be tightly sealed when not in use as you
>also mentioned.
>I mark the date first used on mine, I'll check to see how long I get
>away with next time.  So far it's never been more than 4 months. What
>I do sometimes is make up a new batch and intercompare; the moldy ones
>are always off.
>Regards,
>Joe

Hmmm.  That's weird.  I buy premade buffers from Vinquiry, Presque
Isle, and the WineLab (depending on who I'm ordering other stuff from
at the time), and I've NEVER had a buffer get moldy.  I mark the date
of receipt and opening as well, and throw them out after a year if I
haven't used them up, just for peace of mind.

Electrode storage buffer, sitting in an open beaker with the electrode
in it, does get moldy pretty fast, maybe a month or two.

Dave
****************************************************************************