Chromatography Forum

Greetings everyone,

First time poster here on the forums. As stated in the title, I believe I may have an issue with the pump (Model G1311A) on an Agilent 1200 HPLC system. I checked to make sure it's not a column issue, I've tried various solvents (all degassed), and even replaced the MCG valve. Honestly, at this point I'm completely stumped. Below I've provided an image of a few test injections I ran last week. You can't really tell from the image, but each peak came off sooner and sooner on each injection. If it's too difficult to see, I can resize it and post a link instead. Any and all help is greatly appreciated.

Thanks

Hello

I'd check:

1. AIV (active inlet valve) cartridge
2. Outlet ball valve
*run leak test to see pressure profile
3. Make sure that your degasser is working

First of all - leak test. It is great diagnostic tool.

Regards

Tomasz Kubowicz

1. First question: are you purging ALL four channels even though you may be using only one or two? Important.

2. Pull off the waste line from the purge valve and make sure that NOTHING is leaking from that when the pump is pumping through the column, tough to see with that waste tubing on there. IMPORTANT.

3. I'd consider pre-mixing a simple aqueous-ACN mobile phase and bypassing the MCGV with the Agilent adapter, and make sure that the retention times of your test analyte are consistent. Also measure the flow rate v. time into a graduated cylinder after it exits the detector.

4. As posted above, leak test is important. We've seen small leaks in the ALS loop that don't leak enough to trigger the leak sensor.