How often people develop LC method which has flow rate chang

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How often people develop LC method with flow rate change during the run? Is it common for complex method development or rare cases?
I developed and validated HPLC methods for over 35 years.

Rarely did I have a procedure where the flow rate increased at a certain timepoint to help a later-eluting analyte to elute. Most often I increased the flow rate after the analyte eluted if the pressure was low enough, and I had later-eluting stuff to get off the column. This could be faster to re-equilibrate than initiating a gradient.

And of course a gradient could not be used when we had a single pre-mixed mobile phase.
Flow programming is very 'rare' (it is an indication of a poor method). It is more advantageous to increase the composition of the organic phase slowly during a gradient method (shorter too) in order to 'boot' the target molecule off the column.
When I first started working with EPA Method 1694 I noticed they used flow rate changes (0.150ml/min then 0.250 ml/min then 0.300 ml/min then back to 0.150ml/min). That was the first time I ever saw it, and even though I am running the method I don't use the flow program I use a different column and gradient elution.

It seems to be something Waters likes to do with their "UPLC" instrument methods.
The past is there to guide us into the future, not to dwell in.
Hi KhareM,

Another older Waters method that employed a flow rate change was the AccQ.Tag kit method for amino acid analysis, in the middle of a gradient program.

I agree with these other folks above--it is less usual to vary flow rate during an elution program in HPLC than not.
MattM
Agree with the other posts here. The only time I use a change in flow-rate in a method is to hasten column washing/re-equilibration if possible. Never for analytes - suggests a poor method.
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