Chromatography Forum

I am a new HPLC user. My Agilent 1100 system was blocked. I listed how to diagnose system block as below. Please add more that I missed and correct any mistake I made.

How to solve frit block problem?
How to do pressure test?

Diagnosis for system block procedure:
1. switch a column to a connecter to check if the pressure can drop. Yes, Column blocked. No, it might not be the column
2. open the connecter to see if there is any liquid coming out (1ml/min). Yes, it is after the column. No, it is before the column
3. Open the black valve. With 1ml/min flow, if the pressure is larger than 5 bar, the frit is blocked (the salt concentration of my mobile phase matters)
4. 6-port valve can be used to diagnose the block location

You are on the right track. The general rule is to start disconnecting fittings from the end (downstream) of the system and then work your way upstream. When you disconnect a fitting and the pressure drops, your blockage is just downstream from that fitting.

You can sometimes backflush (reverse flow) a plugged frit, but there no guarantee that it will work. It is usually more cost-effective to simply replace the frit.

Details on pressure test procedures vary from instrument to instrument. Your Agilent 1100 manual should include the pressure test procedure.

Thanks a lot, Tom

Ziminali-Did you solve your problem?

As a preventative you can typically flush with water if you are using water soluble solvents (for example acetonitrile or methanol) on the system. Combinations of high concentration salts (for example phosphate buffers) and organic solvents will precipitate out in the system. A good rule of thumb is to replace the buffer with water and flush out the column/HPLC. See p20 to replace the frit.

http://www.chem.agilent.com/cpdocs/1100 ... enance.pdf

thank
I found the location.

it is the 3 ul heating part that is blocked. I was running 50 C and I stopped flow without lowering the temperature first. so that part ran dry and some salt condensed and blocked the path right away.

thanks everyone again.