Chromatography Forum

One of our multi channel gradient valve (MCGV) in Agilent 1050 leak (Channel A). Should I change the whole set or I can replace the solenoid A only?

By the way, is MCGV for 1050, 1100, 1200 are the same?

The multi-channel valve is pretty eay to swap out; but I don't think there are any user-available parts for it. It sells as an exchange unit, nets about $600 last time we got one (you ship the old one back for credit), and it's been a while. I've got four 1050 systems and four 1100s, their MC valves are different (don't know about 1200s, you could look up on Agilent's site). Yes, if you have a leak, it's bad. So ALWAYS fix first what you KNOW is bad; I saw your other post about your HPLC issues, may all be related to this.

Thanks Consumer Products Guy.

More problems discovered today. The active inlet valve (AIV) gold seal and cap disappeared!!! Some previous groupmates forgot to replace a new one in it (5years ago).

Hence I borrowed a pair from other research group. And used Channel B/C/D only. The baseline variation reduced from 100mAU to become 10mAU now. (Is it ok if I keep this MCGV but not using the leaking Channel A?)

Then I disconnected the tubing from pump to flowcell. Set it to higher flow rate (3ml/min). I saw the flow is not a continous stream, but as a stream for first stroke and droplets for the second stroke.

I suspected there is blockage in the inlet/outlet check valve. And 1050 AIV is "all-in-one" design! There is no cartridge inside the AIV as 1100/1200. Of course, I cannot drop the whole AIV into solvent and sonicate it.

I phoned Sevice Engineer and he suggested to run the system with 3N nitric acid, hoping that dirt will be washed off. I didn't try yet becasue it is already day-end today.

used Channel B/C/D only. The baseline variation reduced from 100mAU to become 10mAU now. (Is it ok if I keep this MCGV but not using the leaking Channel A?)

I'd replace the whole MC valve.

The 1050 AIV is "all-in-one" design! There is no cartridge inside the AIV as 1100/1200. Of course, I cannot drop the whole AIV into solvent and sonicate it.

Older 1050 AIV do not have the replaceable cartridges, the newer ones do, I get a new AIV. And that's same cartridge as used on 1100.
If your company can't afford that stuff, it's probably cutting corners in other important areas as well.

I tried to run Channel B/C/D only and it works! And I flushed the pump with isopropyl alcohol and the dirt washed off. (No need to flush with nitric acid). Now the mobile phase come out as a continuos stream.

Next step troubleshoot is: the degasser

I tried to run Channel B/C/D only and it works!

It works for now; get a new one. If money is that tight, how can your company afford to use the correct type of column, have spare column available, etc. Sorry - can't do this type of work for free.