I like the Fisher AB15 meter. Large LCD display for presbyopic eyes, and
it will do multipoint calibrations. Most laboratory grade pH meters will
do multipoint calibration, however. We typically do a 3 point pH
calibration at 4, 7, 10, but you can do more if you like. I pair this
with a refillable accuTuph combination pH electrode that has a built-in
Ag/AgCl reference electrode. These electrodes have thicker glass
membranes than the usual pH electrodes, and are a little more
student-resistant. The refillable electrode solution allows you to
maintain and use this electrode for many, many years. It is possible to
get 5-10 years service out of these electrodes. If you will be
calibrating concentrated Tris buffers on a regular basis, consider
spending a little extra on a double junction electrode rather than the
single junction electrode. Double junction electrodes are more resistant
to clogging in general and "Tris effect" in particular. (Tris binds Ag+
in the reference electrode, and can make your pH electrode go "wonky"
for a while after exposure.) Gel combination electrodes are worthless,
and I would not consider using one in the research laboratory. They have
very limited shelf and useful life, and cannot be refurbished when they
go bad. And they don't recover gracefully from exposure to Tris. I
haven't tried FET pH electrodes, but they seem needlessly expensive
considering the glass membrane technology works very well and gives
years of service.
Cheers,
_______________________________________
Roger S. Rowlett
Gordon & Dorothy Kline Professor
Department of Chemistry
Colgate University
13 Oak Drive
Hamilton, NY 13346
tel: (315)-228-7245
ofc: (315)-228-7395
fax: (315)-228-7935
email: rrowl...@colgate.edu
On 7/18/2012 2:21 AM, Anirban Banerjee wrote:
Dear all,
May I ask for recommendations for pH meters that work reliably over the range
of buffers and components that constitute common crystallization screens ?
Thanks very much in advance.
Anirban
