[Histonet] calibration of pH meter

John Kiernan jkiernan <@t> uwo.ca
Tue Feb 1 10:49:33 CST 2011

As a student I was told to calibrate the pH meter every time it was used (which was about twice a day at the time), using standard buffers at pH4.0 and 7.0. Nearly 50 years later this is still good advice, and modern meters are much less trouble to calibrate than older ones. If you have to make frequent measurements with closely similar solutions, you might get away with calibrating twice a day.
It's the electrode, not the meter, that changes with time. All pH electrodes deteriorate with time, use and (especially) neglect. A slow response indicates that a new electrode is needed.
Wikipedia has a nice article about pH meters, and there's a web site http://www.ph-meter.info/pH-electrode-calibration that gives advice about calibrating older and newer instruments.
John Kiernan
Anatomy, UWO
London, Canada
= = =
----- Original Message -----
From: Akemi Allison <akemiat3377 <@t> yahoo.com>
Date: Tuesday, February 1, 2011 8:56
Subject: [Histonet] calibration of pH meter
To: histonet <histonet <@t> lists.utsouthwestern.edu>

> Good morning everyone,
> I am curious how frequently you all calibrate your pH meter, 
> particularly when you make up solutions for muscle bx's?  
> Do you do it daily, weekly, or monthly?  I am trying to 
> come up with an acceptable standard in a clinical histology lab, 
> verses a biotech lab, which makes-up large quantities of 
> reagents on a daily basis.
> Thank you in advance for your information,
> Akemi
> Akemi Allison BS, HT (ASCP) HTL
> Director
> Phoenix Lab Consulting
> Tele: 408.335.9994
> E-Mail: akemiat3377 <@t> yahoo.com
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