# Hanna pH meter calibration



## SarahRides (Aug 24, 2011)

If you seal the container, can you re-use the calibration solution for the Hanna pH meters?


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## ibglowin (Aug 24, 2011)

Absolutely!


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## Flem (Aug 24, 2011)

As long a you don't contaminate it by going from one value to another without cleaning off the probe.


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## djrockinsteve (Aug 24, 2011)

I have my 2 solutions in separate containers. They are real small jelly jars so there is enough room to stick the probe in but small enough to use minimal solution.

I use these to calibrate the probe and also to refill the plastic cup that protects the probe when not in use.

Keep the probes wet with 4.01 solution and not water or distilled water. Check the cap frequently (monthly) as it will dry out.


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## ibglowin (Aug 24, 2011)

Just an FYI:

Remember that ideally you want to bracket your sample between 2 standards. So if your measuring a typical wine with a pH of 3.something your actually not doing yourself any favors by doing a 2 pt calibration with 4.01 and 7.0 buffer which normally come with pH meters. If you do this your now calibrated within 4 and 7 but outside of those ranges (either way) your going to be off.

If you really want a 2 pt calibration for a 3.someting sample, use a 2.0 buffer and a 4.01 buffer. Because the pH scale is not linear your better off using a single one point calibration close to your sample pH or bracketing your sample between a high and low buffer if you really want to do a more accurate 2pt calibration.


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## SarahRides (Aug 24, 2011)

ibglowin said:


> Just an FYI:
> 
> Remember that ideally you want to bracket your sample between 2 standards. So if your measuring a typical wine with a pH of 3.something your actually not doing yourself any favors by doing a 2 pt calibration with 4.01 and 7.0 buffer which normally come with pH meters. If you do this your now calibrated within 4 and 7 but outside of those ranges (either way) your going to be off.
> 
> If you really want a 2 pt calibration for a 3.someting sample, use a 2.0 buffer and a 4.01 buffer. Because the pH scale is not linear your better off using a single one point calibration close to your sample pH or bracketing your sample between a high and low buffer if you really want to do a more accurate 2pt calibration.



Yikes! I am really confused now! Sorry............

I calibrated it using the 4.01 and 7.01........... The instructions weren't very useful, it talked about the different types of calibrations.......I really have no idea what those mean or what they are used for or what the difference is. I took the pH of my cranberry which seemed a lot lower than I thought it would be (like 2.64) so I don't think it may have been a very accurate reading. I was kind of tired at the time and didn't investigate further. (I figured I would research another day when I had the brain cells to think about it!  But since that can of worms has been opened............ what is the difference then between the 2 point and single point? can i use either one?


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## ibglowin (Aug 24, 2011)

If your measuring something around 3.0 then just use the single point calibration with the 4.01 buffer. You will get a more accurate reading vs doing a 2 point cal with the 4.01 and 7.0 buffer.


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## SarahRides (Aug 25, 2011)

Ok, thank you! I'm going to play around with it some more tonight, see how to do the single point calibration and re-test to see if I get numbers that look more accurate! So I probably didn't even need to buy the 7.01 or storage solution then.........


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## Runningwolf (Aug 25, 2011)

Sarah, I'm with you on this one. Let us know how you make out.


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## Dougxox (Aug 25, 2011)

djrockinsteve said:


> Keep the probes wet with 4.01 solution and not water or distilled water. Check the cap frequently (monthly) as it will dry out.



They make a storage solution for that, #HI 70300. What is the down fall if you let it dry out besides having to soak it for a few hours before use?


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## ibglowin (Aug 25, 2011)

My experience has been no downfall. I have used these portable ones for 5 years now first testing hot tub water and now wine. I always rinse well before putting the probe away and then dab the tip gently with a soft kleenex. Never had a problem to date and have not had a probe die or malfunction. Just keep any eye on the battery level as that will cause more problems than anything else (screwball readings). If you ever do get weird readings that won't stabilize then I would soak the tip in storage solution for a few hours and that should remove any deposits that might be stuck. 



Dougxox said:


> They make a storage solution for that, #HI 70300. What is the down fall if you let it dry out besides having to soak it for a few hours before use?


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## ibglowin (Aug 25, 2011)

Trying to explain myself better I guess. 

To achieve the best accuracy, the calibration should cover the range of the desired measurement values. For instance if you wanted to measure a solution which had values expected to range between 3.00 and 4.00, one would want to calibrate at 3.00 and 7.01 rather than 4.01 and 7.01. This eliminates the uncertainty associated with trying to extrapolate a value beyond the calibrated values. The resulting readings then are correct at all values between the calibration points. If the readings go beyond the calibrated range, the meter assumes linearity and simply extrapolates the value to be displayed. The true value may be slightly different.




SarahRides said:


> Ok, thank you! I'm going to play around with it some more tonight, see how to do the single point calibration and re-test to see if I get numbers that look more accurate! So I probably didn't even need to buy the 7.01 or storage solution then.........


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