Automatic solvent switching for high throughput LC-MS
Chromatography Forum: LC Message Board: Automatic solvent switching for high throughput LC-MS
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By pc on Thursday, July 8, 2004 - 05:52 pm:

I am switching between 2 LC-MS methods one of which is mobile phase (A: 0.1% FA, B: ACN/0.1%FA) and the other I call Mobile phase 2(A: 95/5 H20/ACN /5mM ammonium acetate; B: ACN/5 mM Ammonium acetate).

Previously I was using an Agilent binary pump and switching these out manually flushing the lines between switching.

Now I have a quternary Agilent pump. I can concievably put Mobile phase 1 (A&B) on channel A and B and Mobile phase 2( A & B) on channel C and D.

And then rewrite my methods...so that it all switches automatically and I do not have to show up on a Saturday to manually change anything.
BUT....flushing the lines....if I write a flush method, low flow, longer time going from 100% B, mobile phase 1 to 100% B moble phase 2 as a means of changing methods....am I going to have any potential problems of buffer precipatation?.....formation of Ammonium formate?

Do I really have to have a 100% B (ACN flush)?
I have no extra channel for this.

Using 100% ACN as mobile phase B, ...i.e. gives poor chromatography for our high throughput 3-4 min runs.

Any ideas appreciated,
Thanks!

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By AA on Thursday, July 8, 2004 - 06:27 pm:

I really dont think you need to spend time flushing. I would think that only thing you need to do is ensure enough equilibration time between swtiches and run a coulple of blank gradients before samples. You are unlikly to precipitate anything going from 100%A to 100% C. The only other thing you could consider is a column switch valve and have one column for each method to speed up the whole process.