Chromatography Forum

I had to use a UPLC recently that had not been used for 3 weeks and I was told by a co-worker to always start by priming the seal wash in fresh seal wash solution and as predicted, the line was blocked even after 20 minutes pumping so I had to inject solution down the other end of the line to clear the air then it was fine.
My co workers have different ideas about how to start an idle system- some say always start with seal wash, some say a long prime of the Buffer/Organic lines is all that's needed. I know, ideally, you should have flow going through it all the time but that's not always practical in a workplace.
Any opinions?

Hi Empowersbane,

Waters strong recommendation (for Acquity-H) is to prime the Seal Wash, then flush the seals, prime the Wash and Purge Solvents and finally all four solvent lines, in that order.

The Startup sequence in the Console does not follow this, unfortunately...Waters recommendation is to (strangely enough) not execute the Startup until the Seal Wash is primed and seals are flushed...or you can start up the way I've just shown above.

The sequence comes from Waters Acquity training, just had the refresher last week.

Best Wishes!

I know, ideally, you should have flow going through it all the time but that's not always practical in a workplace.

I wasn't aware of that. Is this common knowledge or are you confusing LC with GC in this particular sentence?

EmpowersBane wrote:

I know, ideally, you should have flow going through it all the time but that's not always practical in a workplace.

I wasn't aware of that. Is this common knowledge or are you confusing LC with GC in this particular sentence?

It's actually a fairly common practice, especially for ion-pair methods where there can be a long equilibration period on start-up. See, for example, the first paragraph on the second page of this old article by John Dolan: http://www.lcresources.com/tsbible/12111994.pdf

Hi Empowersbane,

Waters strong recommendation (for Acquity-H) is to prime the Seal Wash, then flush the seals, prime the Wash and Purge Solvents and finally all four solvent lines, in that order.

The Startup sequence in the Console does not follow this, unfortunately...Waters recommendation is to (strangely enough) not execute the Startup until the Seal Wash is primed and seals are flushed...or you can start up the way I've just shown above.

The sequence comes from Waters Acquity training, just had the refresher last week.

Best Wishes!

Thanks very much mattmullaney, I did hear of the whole starting with seal wash logic as that's exactly what happened with me- my seal wash line was dry after a few weeks. Ill be sure to start up my machine in that order in future, thanks again.

EmpowersBane wrote:

I know, ideally, you should have flow going through it all the time but that's not always practical in a workplace.

I wasn't aware of that. Is this common knowledge or are you confusing LC with GC in this particular sentence?

It's actually a fairly common practice, especially for ion-pair methods where there can be a long equilibration period on start-up. See, for example, the first paragraph on the second page of this old article by John Dolan: http://www.lcresources.com/tsbible/12111994.pdf

Thanks for the article Tom, very interesting.

From a practical point of view, yes its possible to keep a low flow all the time but then you could be doing something else the next week and forget to keep the solvents and seal wash topped up!

@ EmpowersBane,

You're welcome. What did they say in the film Glengarry Glen Ross..."Always be priming"...or was it "Coffee is for primers"...

Sorry, poor joke. Good concept, though.

If you had good chromatography when it was shut off, it should be fine. If you are using buffers, then you should prime seal wash. Dont leave water in bottle for a week or more due to microbial growth.
A good practice is to teach everyone to prime all 4 lines, seal wash, needle wash before every run or once per week.
Although not always necessary, it can eliminate issues with inexperienced users.
Alot of people run at slow flow 0.05 ml/min for days no problem. only 72 mls per day

be aware, though, that if lab procedure is to leave the system pumping slowly for potentially long periods, one should also get in the habit of leaving the system in a solvent that won't grow bugs.

What is the best solvent to leave lines in (all lines) if leaving a system for a week or two? 90% Organic or would even the 10% water be enough to grow bugs?

Hi EmpowersBane,

Waters seems to like 80:20 dI H2O/IPA or MeOH, Agilent seems to like 90:10 dI H2O/IPA. The other folks note that the % Organic has to be high enough to keep the bugs from growing...and I agree with them. Where I work now, we use the Waters favorite with MeOH and for one system may switch to the IPA version once our QDa is up again.