Chromatography Forum

Dear all,

how do I prime an Agilent HPLC that has not been used for a month?
The manual says the following:
"Use a syringe to draw enough solvent for completely filling the
tubings to the pump inlet before continuing to prime with the pump."
Is it thus correct to draw solvent through the degasser? Is the degasser supposed to be turned on in the meantime?

Sorry if my questions sounds a bit stupid.

MrGC wrote:
Dear all,

how do I prime an Agilent HPLC that has not been used for a month?
The manual says the following:
"Use a syringe to draw enough solvent for completely filling the
tubings to the pump inlet before continuing to prime with the pump."
Is it thus correct to draw solvent through the degasser? Is the degasser supposed to be turned on in the meantime?

Sorry if my questions sounds a bit stupid.

If it is empty or has a lot of air in the system I disconnect the line going into the inlet valve at the bottom of the pump and attach a syringe there and slowly draw the solvent through from the bottle until I don't get any more air bubbles exiting the degasser. Depending on the degasser it can be up to 20ml dead volume. If you have the micro degasser, you have to pull slowly, 10ml/minute or less, the old large volume degasser you can pull as fast as it will flow through.

You want to remove as much air as possible so the pump is operating dry as little as possible since that can cause wear on the seals. Once you get flow down past the degasser you can either continue to pull with the syringe or let gravity pull solvent through until the bubbles disappear. The degasser can be on the whole time.

James_Ball, thank you very much for your answer!

Remember to purge ALL channels at 5ml/min for at least a few minutes each, even if your analysis uses only one or two channels.We purged each day of use, and if an aqueous channel at 5ml/min had pressure over 8 bar, time to replace the PTFE purge frit.

Old 1050 degassers had like 40 ml dead volume PER CHANNEL !!!

Thank you Consumer Products guy!
Why is it important to purge the channels I am not using?

MrGC wrote:
Thank you Consumer Products guy!
Why is it important to purge the channels I am not using?

So that the multichannel gradient valve will operate properly ! After having issues in the early days of the multichannel gradient valve and learning of this way to avoid issues, this was part of EVERY DAY start up of the units.

... and if you never purge one particular line, and it ends up full of algae, gunk, bubbles and assorted ecosystems, then if anyone ever selects that line, even for a few seconds, you have a whole biome of unwanted stuff heading towards your column...

It is unnecessary to purge all the channels daily. Just fill the unused channels with water containing 20% of organic solvent or with a pure solvent such as isopropanol for longer idle periods; purge only the used channels on the day of work.

Another standby option, if solvent in all channels is miscible and safe for the column, is to make a 25/25/25/25 isocratic method pumping 0.1-0.2ml/min and allow it to run during idle periods, but not more than the weekend. I always did this to prevent growth even in the aqueous lines as it seemed as long as the solvent was moving, it was less likely to grow algae.

Of course if one channel is high concentration salts, then you would not want to mix that with the organics. One other advantage to keeping a low flow was that the pump seals never stick to the plunger which can happen if they sit for long periods of time.