gradient composition change

[leonvdbos]

Hi,

We have Waters Alliance and Agilent 1100/1200 equipment availabe.
Externally a method is developed on Agilent equipment.
I wonder if the gradient that's used can be easily transferred to Waters equipment.
The gradient goes from 59% A to 52% A in 35 minutes, which is a change of only 0.2%/min
Mobile phase A consists of water with 0.2% TFA and mobile phase B consists of acetonitrile with 0.2% TFA
The flow rate is 200 ul/min

I know this has probably something to do with the flow accuracy and the capabilities of the gradient mixer.
Can somebody give me a clue what's the minimum change in %A/min that's reproducible?

Testing is probably the best way to find out, but I also want to know from theory. Also to be sure that the experiment I'm doing to verify the method on Waters equipment is not just a lucky shot.

Regards,

Leon

[Alex Buske]

Testing is the best way to find out.
It depends on the "delay volume" or beeing more correct on the "delay time", that is the time from the point when the eluent is mixed to the column head.
With a Alliance the delay volume is around 1 ml, so for 0.2 ml/min the delay time is around five min.
For the Agilents it depends on the configuration.

Alex