pH meter calibration. Was Re: [Histonet] Alcian Blue

John Kiernan jkiernan <@t>
Mon Dec 7 23:27:59 CST 2009

A pH meter must be calibrated hourly or daily, not monthly! 
In a research environment, with frequently changing chemicals that might damage the glass electrode, you need to calibrate against standard (usually bought) buffers several times within every day. pH meter electrodes are horribly fragile and horribly expensive. Replacing them is a big item in every lab's budget. 
John Kiernan
Anatomy, UWO
London, Canada
= = =
----- Original Message -----
From: Diana McCaig <dmccaig <@t>>
Date: Sunday, December 6, 2009 13:49
Subject: [Histonet] Alcian Blue
To: histonet <@t>

> In the past, when we made up 1% Alcian blue in 3% acetic acid (using
> bottle distilled water), the pH was always 2.5.  We did not 
> have to
> modify it to get the proper pH.  Still using the same 
> powder, we are
> getting a pH of 2.1.  I hate to adjust it because it seems 
> to affect the
> staining.  Any suggestions.  The pH meter is 
> calibrated monthly.
> Diana 
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