Can I run my instrument from 0 to 100% or do I have to stop at 5 to 95%?
So, historically, like when I was a kid, I started doing HPLC in 1980, we were taught to always leave some organic on the column. When you do a gradient, don’t go to 100%; leave a little water on the column.
The theory was if you leave a little water on the column, it’ll equilibrate faster. And it’s a cool theory. Turns out, the data does not support that theory.
So, in my opinion, there’s absolutely no reason why you cannot run an HPLC gradient to 100% methanol, 100% acetonitrile. We do it routinely. There’s no data to say equilibration takes any longer, or it has any effect on the chromatography. So, I’m a big fan of going all the way up to 100% methanol, acetonitrile, THF, whatever you’re using.
Now, on the low end, can I start an HPLC gradient at 0%? Well, not really, not on a regular C18, because you’re not going to damage the column, but you’re just going to cause that phase collapse.
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