Top tips for the maintenance of pH Meters

You will all be aware how important it is for pH meters to be accurate for BTEC, A-Level and beyond work for example determining an Acid Dissociation Constant. Firstly never store the probes in distilled or deionised water - use tap water. Secondly never touch the glass probe or it will be depolorised and always make sure that there is no bacterial groth on the probe by immersing in methanol for a few minutes. Thirdly allow the probes to sit in 3 M KCl for 30 minutes (especially for Silver-Silver electrodes. Next check the response by placing the probe in 0.1M HCl for 5 minutes then place in 0.1M NaOH for 5 minutes - the response should be fast. Finally calibrate the probes in accurately prepared pH4.00 and pH 7.00 buffers (place in pH 7.00 buffer first), check the speed of response and store in pH7.00 buffer until required (change the buffer every 5 days if the probes are frequently used, if not store dry). Good luck.:);)

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Cool thanks for that George.
Thanks mate, and you're so right it is cool. I decided to create this thread on account of the problems other Memberes have endured with these pH Checkers- whether allowing Students to calibrate them (and goose them in the process) and the slow response over time due to Microbial films etc. I hope that my methods will be of help to others.:);) No hidden meaning in the wink PrepAdmain @prepAdmin :D:D:D
 
Thank you from me too George.

I was surprised they need to be stored dry for long term storage. This just goes to show an old dog can learn new tricks.
 
Thank you from me too George.

I was surprised they need to be stored dry for long term storage. This just goes to show an old dog can learn new tricks.
mine have a sponge in the cap (the £100 ones) and say to store them with the sponge damp? and others expensive probes i have used in a previous life have said store in pH4 buffer.
 
@GeorgetheScienceTech I was wondering about the reasoning behind using tap water and storing dry, would it be possible to enlighten me?

Also the methanol tip is ace!
mine have a sponge in the cap (the £100 ones) and say to store them with the sponge damp? and others expensive probes i have used in a previous life have said store in pH4 buffer.
Thank you from me too George.

was surprised they need to be stored dry for long term storage. This just goes to show an old dog can learn new tricks.
Enlighten you I will Hugh @Hugh The Hanna type pH probes are sent out dry. Being dry (assuming that they have been cleaned) means that there will be no microbial film formed which means that the response time of the probe will be as it should be. If stored in pH 7 buffer for extended periods a microbial film will form so it is well worth cleaning them and storing them until required. These probes are only required for a few required practicals per year. Before they are used it will be necessary to soak them in Tap water for several hours to "condition them" then place them in pH 7 Buffer. Silver-Silver electrodes must never be allowed to dry out and must be maintained in 3M KCl.:);)
 
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Enlighten you I will Hugh @Hugh The Hanna type pH probes are sent out dry. Being dry (assuming that they have been cleaned) means that there will be no microbial film formed which means that the response time of the probe will be as it should be. If stored in pH 7 buffer for extended periods a microbial film will form so it is well worth cleaning them and storing them until required. These probes are only required for a few required practicals per year. Before they are used it will be necessary to soak them in Tap water for several hours to "condition them" then place them in pH 7 Buffer. Silver-Silver electroded must never be allowed to dry out and must be maintained in 3M KCl.:);)
If you use them with foods like milk etc you can also soak them in a protease to clean them.
 
I found one of our pH probes today to have muddy water where the storage solution should be. (No idea how long they've been like that, but they we new a year ago and I calibrated them.) Any advice on trying to save it, other than rinsing lots in distilled water? Cheers
 
I found one of our pH probes today to have muddy water where the storage solution should be. (No idea how long they've been like that, but they we new a year ago and I calibrated them.) Any advice on trying to save it, other than rinsing lots in distilled water? Cheers
We have some mettler toledo pH probes and I have found a couple of mine like that. I'm aiming to follow the instruction manual's advice which is to soak in 0.1M HCl overnight. Then carry out a calibration! I also read somewhere (t might even have been here) that if you have detachable probes, keep one probe with one machine to allow the calibrations to remain with that probe!

And it is only now I see the date of this comment! haha
 
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