All there is to know about flash purification – a blog by Biotage
How to choose between linear gradients and step gradients for flash chromatography
Varying the concentrations of mobile phase solvents during flash purification chromatography enhances the ability of the technique to effectively isolate the desired compound from reaction byproducts and unconsumed reagents. Choosing how these concentrations will be varied over time has a significant effect on the purity and recovery of desired compounds.
What is the best starting strong solvent %? What is the ending strong solvent %? Should the mobile-phase concentrations vary gradually in a linear manner or should they vary step-wise or something else altogether? Most separations are performed once, occasionally a handful of times. Because of this, spending effort optimizing a gradient is just not very productive unless there are aids in choosing the gradient profile that provides an effective purification with minimum effort.
Software in flash chromatography instruments, makes it simple to create a gradient. Now, what should that gradient look like?