Author Topic: pH Equipment? Why? For what?  (Read 19018 times)

zenith1

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Re: pH Equipment? Why? For what?
« Reply #15 on: December 30, 2009, 04:19:51 AM »
Have a look here Divey. I think a few of us here at the forum use this one or one like it.
http://www.extechstore.com/index.asp?PageAction=VIEWPROD&ProdID=634

humble_servant7

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Re: pH Equipment? Why? For what?
« Reply #16 on: December 31, 2009, 05:52:55 AM »
Have a look here Divey. I think a few of us here at the forum use this one or one like it.
http://www.extechstore.com/index.asp?PageAction=VIEWPROD&ProdID=634


What would you recommend as the best one for getting on that site for around 300 bucks?

Tea

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Re: pH Equipment? Why? For what?
« Reply #17 on: December 31, 2009, 08:43:35 AM »
$300   :o  Good lord, I paid $50 for mine, and it works just fine.  Are you needing to use this for other purposes too?

zenith1

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Re: pH Equipment? Why? For what?
« Reply #18 on: December 31, 2009, 04:06:54 PM »
I agree with Tea- you can get a good one for around $100.

wharris

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Re: pH Equipment? Why? For what?
« Reply #19 on: December 31, 2009, 05:00:48 PM »
thats about what mine cost.  (100)

Tea

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Re: pH Equipment? Why? For what?
« Reply #20 on: January 01, 2010, 01:32:31 AM »
I reckon a better deal would be $100 on the pH meter, $100 on some cheese moulds, and $100 on cultures, spores, etc.

Offline DeejayDebi

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Re: pH Equipment? Why? For what?
« Reply #21 on: January 01, 2010, 03:47:36 AM »
I only paid $30 for my first one (which I used for beer not cheese) and it lasted several years until I forgot to add liquid to the cap after making cheese one night.  :(

I have to say though ... I have been making cheese for over 30 years without using a pH meter and I only messed up the first crottins I made a few months ago. Partly by going on vacation for 2 weeks and leaving them alone.

Michael_A

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Re: pH Equipment? Why? For what?
« Reply #22 on: January 09, 2010, 04:40:07 PM »
Hi Folks,

First post here.  I have been reading a few of the pH equipment threads and I haven't noticed any mention of cleaning your pH probes.  At the same time I have noticed mention of problems with probe lifetime, etc.  When you are sampling biological materials it is important to clean the proteins and lipids off of the probe tip very regularly.  It is a simple procedure and it is outlined about 2/3 of the way down this page Proteins and lipids aggregate and block the semi-permeable membrane that is the key to probe function.  And since they may be charged themselves they also affect the ionic micro-environment of the tip.  At the lab I used to work in the tip was placed into a vial of the urea solution after every session of measuring culture media.  Especially important is you are interested in that last 0.01 unit.

Michael

zenith1

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Re: pH Equipment? Why? For what?
« Reply #23 on: January 09, 2010, 08:30:16 PM »
Thanks Michael- that is something we all should look into.

Likesspace

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Re: pH Equipment? Why? For what?
« Reply #24 on: January 09, 2010, 10:45:29 PM »
Michael....
Welcome to the forum and great first post!
I've also read the necessity of using a cleaning solution on the probe but as yet I have not purchased any.
I do however always "swirl" the probe in distilled water after each test, I make.
Is this enough to keep the protein buildup from happening, in the first place?
My procedure is as follows:
Keep the Ph meter in a small container of distilled water while making cheese. (this is only done while making cheese and after I'm finished I put the meter away with the cap filled with Ph 4.0 solution).
Take a sample of whey from the cheese pot.
Swirl the Ph meter in the distilled water, remove and dry on a clean paper towel.
Place meter in the whey sample and record reading.
Turn of meter and rinse under tap water.
Dry with paper towel and then swirl in distilled water and leave for next use, (usually every 20 minutes or so).
I'm hoping that this procedure will both give accurate readings AND keep the protein buildup from happening on the probe.
Please let me know if I'm correct, when you get the chance.

Dave

Michael_A

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Re: pH Equipment? Why? For what?
« Reply #25 on: January 10, 2010, 01:35:57 AM »
Hi Dave,

Thanks.  Your procedure for using the meter sounds great to me, though you don't have to worry about drying the distilled water from the probe before using it for the test.  I know some of these probes are much more robust than the ones I was used to using, but the less physical activity they have to endure the better they like it.  Kind of like me in that respect I guess. :D

The problem with the proteins, in particular, and the lipids (fats) is that they aren't very soluble in water, they like to stick together and they like to stick to membranes.  Since it's generally not recommended, at least that I have seen, to use soaps or detergents on pH probes and you shouldn't spit polish the membranes either, you have to come up with something that does the job in a gentle and neutral sort of way.  Urea molecules (found in urine, hence the name) are neutral, but they are sort of funny little creatures.  They like to play ring around the rosy with proteins and fence them into a little container they build called a clathrate.  You can look it up if you are bored beyond tears.  This solubilizes the proteins and allows them to drift away into the water solution and thus clean the membrane.  The NaOH solution (sodium hydroxide, Drano) turns the lipids into free fatty acids which are soluble in water as well.  Actually it turns them into soap, but the quantities are small.  Those are the two main problems I would foresee with whey.  This was not a trivial problem with the research grade probes I was using.  I had to redo whole experiments where the pH of the buffers I made was off by a point or more, ie. 6 instead of 7, because a previous user had spent an hour or two testing cell cultures or cell culture media and had not cleaned the probe with urea or labeled the meter as contaminated and not to be used without cleaning.

Urea is readily available online or maybe even at a camera shop where they sell developing supplies.  If they still do that.  I don't think you need the highest grade or even food grade as you will rinse it and any soluble contaminants away from the probe when you rinse it in distilled water after cleaning.  And it is pretty much not hazardous.  I guess you could water your houseplants with the leftovers if they are looking a little pale.

Hope this helped,

Michael

wharris

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Re: pH Equipment? Why? For what?
« Reply #26 on: January 10, 2010, 01:57:27 AM »
I keep a wash jar full of rinse solution.  I use the squeeze jar to wash the tip from time to time.  Certainly before and after ever batch.


Here is what i bought

Likesspace

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Re: pH Equipment? Why? For what?
« Reply #27 on: January 10, 2010, 02:13:23 AM »
Michael, I really appreciate the information. You went into a lot of detail to explain the need for cleaning the Ph probe and that's one reason that I have so much respect for the members of this forum. People are willing to share their knowledge, (in detail), which in the long run makes us all better makers of cheese.
I guess I'll be buying some cleaning solution soon.

Wayne....
Are those all solutions used for cleaning or are some of them for calibration?
If this is what is needed for cleaning, could you please provide a link for purchasing?
Thanks in advance.

Dave

wharris

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Re: pH Equipment? Why? For what?
« Reply #28 on: January 10, 2010, 02:19:53 AM »
The cleaning solution is in the wash bottle.  The other bottles are my calibration solutions.  I think i did include the link.

Michael_A

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Re: pH Equipment? Why? For what?
« Reply #29 on: January 10, 2010, 02:49:00 AM »
Nice setup Wayne.  Is that a stirring hotplate in the background?  With a titrator over it?  I'm envious of the equipment and the space.

That solution looks like it should do the job.  I notice the instructions mention immersing the tip in the solution for 5 minutes.  I also see it contains a phthalate, which is having a bad rep at the moment.

A couple of general lab comments for other readers.  If you have solutions in squeeze bottles or other non-original containers always label them with masking tape marked with permanent marker if they are not dedicated to a use or with permanent marker on the bottle if they are dedicated to a particular use.  Do this before you fill the bottle.  Saves a lot of woes when you need something in a hurry and you haven't got time to think of which is which.  Also, always close your pH standard bottles immediately after you take solution out of them.  They absorb CO2 out of the air and the pH drifts over time.  Never put anything into the standard bottle itself except a clean pipette.  And store all silver containing solutions in a cabinet where they are protected from sunlight and fluorescent lights as they cause the silver to precipitate out.  Also, none of these has an indefinite shelf life so order a new batch every year or so.  I know this sounds fussy, but in the long run it protects your equipment and the integrity of your data.  Who knows, you might discover the worlds next great cheese and want to be able to make it again. :)