Chromatography Forum

First, as I said before, while I have a lot of HPLC experience, it was all on Water's equipment and I am unfamiliar with Agilent HPLC equipment and trying to figure things out as I go along, so all suggestions are welcome


Awhile back I was having a problem getting a baseline on the RI detector on the system. It seemed to go away when I tightened up the pre-column holder... Then I did not use the system for about a week. Last Thursday when I started it up again, the RI was drifting downward very significantly with a steep slope even after equilibrating for several hours... I noticed a leak at the pre-column inlet (though the TCC was not detecting a leak) and thought maybe that was the problem.

So figuring that the ferrule was not seating right, I changed the line from the heat exchnager to pre-column using new nuts and ferrules.

Now I keep getting leak errors from the TCC module, but for the life of me I can't see any leaks visually at it or using the kimwipe test on all the fittings in the flow path.

I really need to get this up and running ASAP, so I would greatly appreciate suggestions.

Thanks,
- Karen

Run the leak test. It is in the diagnostics section of chemstation. Basically you block the flow in various places with a solid nut and run isopropanol following the instructions. That should tell you if their is a leak upstream of the nut. You can run it at various points to narrow it down.

Is the running pressure less than normal? Is it fluctuating rapidly? Could be a faulty leak sensor also. make sure the mobile phase completely evaporated from the last leak. Put some methanol or ethanol on the sensor and blot it up with a kimwipe. There is also a rotor seal in the column module that can go bad. You might also try shutting everything down rebooting the computer and starting it up again.

Run the leak test. It is in the diagnostics section of chemstation. Basically you block the flow in various places with a solid nut and run isopropanol following the instructions.

I did run it... with Water as that is what the pump manual said... But I see now that the on-line help says to use IPA!

The results I got with water said indeterminate and to run the valve test... But as the instrument is only 2 months old (and allI've run through the system is water and ACN ), I figured that was unlikely.

Is the running pressure less than normal? Is it fluctuating rapidly?

Pressure was normal.

Could be a faulty leak sensor also. make sure the mobile phase completely evaporated from the last leak. Put some methanol or ethanol on the sensor and blot it up with a kimwipe.

I don't know where the sensor is, but liquid on the sensor must have been the issue. Today I started up the system and I'm not getting the error! Must have dried up overnight!

Well at least I'm learning this hardware.

Thanks,
- Karen

Karen - on Agilent thermostatted column compartments (1050, 1100, 1200, 1290 - haven't seen 1260) the leak sensor is in the middle, bottom, somewhat obscured. If there's a leak causing a shut-down, we use cotton-tipped applicators to soak up any liquid, then let it dry 10 minutes.

There's a heat exchanger on each sise, sometimes an accessory column switching valve, and, or course, all column connections. If a ferrule won't seat well, install new tubing or use fittings with PEEK ferrules.

When you do the "KimWipe test" do you leave a KimWipe under the fitting for several minutes while it's pumping? Also, you know this, but for others: pressure is way higher at inlet side of column than on the exit side.