Ph calibration fluid - Who's the guy with some?

melev

melev

Club President
Staff member
Board of Directors
Sponsor
[A few months ago, we had a member (or perhaps merely a person posting here that is not a member yet) that said he had calibration fluid to adjust our pH monitors.

Who's the guy, and do you still have some? I need to calibrate mine soon.]
 
[Marc, that would be me. I always have some, but you're quite a way from me. Can you wait until the next meeting?

I will also be at Tranquilscape on Saturday morning, and in the I20/loop 820 area on Saturday afternoon if you want to meet up.

Just let me know: 972 463 0444 (evenings) ian_sawyer@yahoo.com]
 
[Yes, I can wait until the next meeting. Isn't that going to be a week from today at Gary's house?]
 
[Ian,

Do you sell calibration fluid? If so, how much do you charge? I don't need any right now, but will in the future. I live a bit closer than Marc...I'm in Richardson.

Thanks...]
 
[Jody

I can get you bottles at the same price I pay for it (I work in a laboratory). Its a little cheaper than what you pay, but not much. It is worth your while if you order about a week before a meeting that we would both be attending.

Marc, I may go to the September meeting, I have to look it up in Yahoo maps. I am far east of Dallas, and FW is quite a hike.
Saturday is much better cos I am definitely in the area on other business. Maybe I can get it to a member who is going to go to FW? I don't want anything for it, btw, its only a sample size, unless you want to buy a pint for about 3.50 <--- will have to check the price, so don't quote me.]
 
[I'm going to be attending MACNA in Louisville Kentucky this weekend, Ian. So I'm not going to be around, sorry.

We'll just work something out when our schedules work in conjunction with one another. I believe I need two fluids, not just one. 7 and a 4,10, right?]
 
[Marc

You can get away with just a 7 buffer, but a full-fledged "pro" like yourself, who demands absolute precision, would probably like to get a 10 buffer, so that the pH range of interest is "bracketted" by the calibration buffers.
You would need a pH meter that is capable of 2 point calibration to be able to make full use of both buffers.]
 
[Ian,

How long does calibration fluid last? I got some powder with the PH meter I bought....mixed it with RO/DI water and have it in some small tupperware bowls in the pantry. About 2 months old now.

Thanks! And I'll let you know when I need some (at least a week before a meeting, like you suggested)...]
 
[@Ian Sawyer wrote:
Marc You can get away with just a 7 buffer said:
Ian, my Pinpoint Monitor has two set screws next to the two different numbers, so I'm guessing this is why I need both. Pro? More like perfectionist.... :lookaround:

This is the one I'm using. I'd like to calibrate it accurately, and I'll be happy to buy the solutions from you. Where do I store it? How long is it good? I have a feeling I'll only calibrate every so often. What is the standard? Monthly?

Do you have a source for replacement probes?

electronic_thermometer.jpg
alt="">]
Click to expand...
 
[Jody

The pH Buffer solution will last longer if you clean crud off your probe before you dip it in there. Buffers are designed to "cope" with foreign matter being added to them, but there is a limit to how much abuse they take. In normal laboratory use, buffers are changed out weekly, or if the solution becomes visibly contaminated. A good rinse in RO/DI before dipping your probe into the solution will do wonders for the shelf life of your buffer. When you make up the solution from powder, you can use 5% for calibration, and save the other 95% for monthly changes (store the 95% in a plastic water sample bottle in the refrigerator. Discard if the buffer becomes cloudy. This should give you 20 months of use from 1 powder sachet, the 1 pint bottle that I sell will be good for about 3 years. We portion off 0.5 oz amounts into plastic vials (I can get you a couple of these vials for free when you buy the buffer). These are changed weekly in out lab.

Marc
I can see a screw next to a "7", but the thermometer is obscuring the second screw, maybe? Your manual should say how to do a 2 point calibration, if it is capable. What does the other number say? If it says "slope", then you should be good to go.

The fridge is a good place for buffers. Only take out enough for current use, so that you don't risk contaminating the whole bottle. The 2 things that can screw up your buffer are algae/bacteria, and physical contamination by inserting dirty probes. Manufacturers usually put an expiry date on the bottom of the bottles, but in reality, the solutions can be OK for years beyond these dates. Its a case of limiting their liabilities.

In laboratories, it is common to check pH readings against buffers, immediately prior to use. This can mean checking 30 or 40 times a day. If the meter is more than 0.05 pH units from nominal values, then a full calibration is carried out. This will ensure that your readings are perfect, and is not so bad if you are only doing a weekly check. To be honest with you, even $1000 pH meters will drift around over the course of a day, and your model is "economy" by comparison. You really need to check prior to each reading.

Yup, I can get hold of spare probes for your meter. Just give me the part# if you can, and I will get a quote for you. I don't want to make any money from my services, you will pay what i pay, not a bean more.

Take care y'all]
 
[Ian,

Thanks a lot for your information and kindness. I will be more than happy to pay an extra bean or two for inconveniencing you when the time comes. :D]
 
[Hi Ian,

I just got back from MACNA a few hours ago, and am catching up on posts and such.

Under the "7"'s set screw, there is another screw with the numbers " 4, 10 ". I might still have the manual in the box.

I'll see if I have a part number for the probe as well, in the next day or so.

I too would like to get the little test tubes like you mentioned to Jody.

Is there a way to clean a probe? Mine hangs in the refugium , and is accumulating a beautiful coating of coralline. :wwww: Is soaking in Ro/Di good enough, then just sponge it well? Or could I turn it off and soak the probe in vinegar, or would that eat away at the sensor?]
 
[Marc

Procedure would go like this:

1) insert probe into 7 buffer, wait for stable reading, then turn the "7" screw until 7.00 reading is obtained.
2) rinse probe in RO/DI
3) insert probe into 10 Buffer, wait for stable reading, then turn the "4,10" screw until 10.00 reading is obtained. Voila

I would recommend removal of the probe from your aquarium when you aren't taking a measurement. Coralline algae build-ups will be detrimantal to probe performance. If vinegar is the best way to dissolve coralline, then vinegar is the best way to go for probe cleaning. Vinegar is just a solution of acetic acid, which is something that your probe should be able to withstand with ease. The bulb at the tip of the probe, however, is a very delicate, thin layer of glass, and is easily damaged by rough handling. Chemical dissolution/dispersion is the best way to go.]
 
[Thanks Ian, that's excellent information!]
 
[Ian,

Well, looks like I might need those calibration fluids sooner than I thought. I opened the little bowls I was keeping the stuff in and there was a little 'fuzz' growing on the lid. I guess I would need 7.0 and 10.0. My meter does have a calibration screw for 7 and another for 4 and 10. I would like to get a couple of those plastic vials you mentioned, too. I keep the probe end in Ph electrode storage solution. I also have some probe cleaning solution that is kept refrigerated, as stated on the bottle. I do rinse the probe off with RO/DI water before going from one thing to another. I have never used the cleaning solution yet, but how often do you suggest the cleaning solution be used being that it says to soak it for a couple hours in the cleaning solution, rinse with water (ro/di), and then store for several hours in storage solution before next measurement?

Let me know what we can work out. I work downtown, so if you work down there somewhere, I could always pick it up from you there. Whatever we can work out. I don't need it immediately or anything, just like the accuracy tons better than the testing kits.

Thanks a bunch!

Let me]
 
[Jody

I think our supplier will deliver to your workplace or home via UPS ground let me check tomorrow, and I will repost.
I have a small freebie quantity you can have in the meantimeifyou get real desperate. I work in Garland so maybe I can leave it by the side of a call box (brown paper wrapper) for you to pick upon the way home.

Posting soon
Ian]
 
[Jody

Sorry, I thought I had this posted (doh). The price for 1 pint of 7 buffer, and 1 pint of 10 buffer, is a total of $7.00. Shipping by UPS to your address would be $7.50, which kinda sucks. If more people bought some, and I know Marc is interested, then I could get them shipped to me, and I could break them out at the next meeting for maybe $9.00 for the 7/10 set. I can give you some vials for free.

If you're happy to pay shipping let me know. If you can wait, I'll try again in the group buy forum for distribution at the October meeting.]
 
[Ian,

I just thought you got busy...no big deal. I'd rather wait for a group buy. I may not be able to make it to the meeting unless it is in our area, I get off work at 5:00 and wouldn't be able to get all the way to Ft. Worth in time. However, I could either meet you at your work and pick mine up, or something like that if there are some others that also want to order some.

Thanks a bunch!]
 
You must log in or register to reply here.
Top