baseline drift using RI detection

[Ricardo]

I am developing a method for the analysis of methanol, ethanol and glycerol usng a Varian Metacarb 67H column using RI detection. I am unable to get a stable baseline as it is drifting down until it flatllines. unable to make any injections.
I have flushed the system with IPA and water and got a very nice baseline. My mobile phase is 0.025N (0.0125M) H2SO4.
The detector is an older HP 1047A. Each time I flush or balance the system, the same thing happens. I have checked for leaks.
My temperature is 50 C at the column and detector.

Any help would be greatly appreciated

Ricardo

[carey53095]

Hello - I too have an RiD, but not for your application. I must let my system equilibrate 24-30 hours before it is stable. Usually, I turn on the HPLC and begin pumping at 0.2ml/min overnight, with the RiD on "purge" to clean out both the sample cell and the reference cell. Then the next morning I set the pump to the speed for my method, and let it go for another hour or so. Then I close the "purge" on the RiD, and let it go for another hour yet. Hope this helps you. Best of luck!