Odd problem: Pressure rising rising until system shuts down

[dkreller]

Hi,

Odd problem I haven't seen before. I am working with a self-packed column that contains 200 micron quartz sand. These columns usually have only ~100 psi backpressure. However, right now when I go to start an experiment, the pressure is 500-700 psi and then the pressure rises at a rate of at least 100 psi/ min and before I can do any meaningful work, the pressure hits the max. setting and the system aborts. Very odd.

When the column is replaced by a union the pressure stays stable. Even that is a bit high right now. It is about 60 psi with that union in place whereas before it would be even lower, but at least it stays steady.

So, this wierd pressure problem seems to have something to do with the column.

It is a Waters Delta 600 pump, with optical (dual wavelength absorbance and fluorescence) detectors.

Any thoughts, kind chromatography forum members/experts?

Thanks,

David

[Slammy1]

Sounds mobile phase related, actually. I remember telling a Jr chemist to flush a column with water and he had the exact same issue, then I realized he pulled from the tap... Try filtering mobile phase, perhaps run the column reversed into a beaker at a low flow rate to unclog the column frits. It might have been a transitioning issue as well.

[dkreller]

Hi,

The problems were solved by the purchase of new blank columns for packing. I did some trouble shooting and narrowed it down to the colomn frits. Perhaps we could have gotten away with just acquiring some new frits but these columns have gotten such a workout in the last few months that the threads were getting beat up as well so we just ponied up for new columns. The frits may have gotten clogged up partly because we have ran a bit of calcium through the system. We sonicated the frits with 10% nitric acid, but that only partly alleviated the problem.

David