Can anyone suggest a method for in-line pH measurement in aqueous HPLC streams? WE would like to be able to measure and monitor the pH of our system pre-column (post mixing and degassing) and post column but have not been able to identify a good method for doing this.

Thanks in Advance

Ken Anderson

What you want is a "pH flow cell" (my terminology). I know such devices exist, but I can't put my finger on one that would provide a sufficiently low internal volume to be useful to you.

VWR offers a flow-thru adapter (C/N 61161-358, $70) for 12 mm dia. pH electrodes, but the volume of that is likely to be excessive.

One place I know such devices are used is in pH-zone refining using high-speed countercurrent chromatography (HSCCC). HSCCC often uses approximately the same flow rates as HPLC, so the volume considerations for the pH sensor would be similar for that technique.

Check the Pharma-Tech Research Corp. website and find your way to the book listings. There are one or more book chapters on pH-zone refining. You can probably get a listing of apparatus from those (via interlibrary loan of the book).

Oops! Sorry. Got the wrong URL Try this one for Pharma-Tech Research Corporation.