Using a pH meter requires that you add dist. water to the glass flask, swirl it around and "hope" that something will be "trapped" by that water that will give you an idea of the residual pH that may be in the glass. Both things are quite improbable. Instead of the pH meter or the paper indicator I always added to the water from the flask few drops of bromothymol blue that would turn yellow at pH<7 and blue at pH>7 On the other hand if the glass is properly washed in distilled water you will never get a pH other than neutral. René J.
--- On Wed, 9/14/11, Clare Thornton <cthorn...@dahlchase.com> wrote: From: Clare Thornton <cthorn...@dahlchase.com> Subject: [Histonet] CAP GEN.41770 Glassware cleaning To: "'Histonet@lists.utsouthwestern.edu'" <Histonet@lists.utsouthwestern.edu> Date: Wednesday, September 14, 2011, 4:07 PM This checklist question has a sample procedure for how to check for residual detergent in glassware. The procedure says to use a pH meter. We've always used pH paper. However, in reading their recommended procedure, you need to look for a change of greater than 0.2 pH units between source water and glassware pH. Does anyone else use pH paper vs. a pH meter? We only use our pH meter very infrequently and will calibrate it just prior to use. If we use it for glassware cleaning, we'll have to calibrate more regularly, something I'd just as soon avoid if possible. We've never had a problem with our glassware cleaning procedure with CAP in the past. Any advice? Clare J. Thornton, HTL(ASCP), QIHC Assistant Histology Supervisor Dahl-Chase Diagnostic Services 417 State Street, Suite 540 Bangor, ME 04401 cthorn...@dahlchase.com _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet
