Chromatography Forum

Friends,

i saw one of my compound is getting separated in combiflash companion, but not in biotage. Both are silica columns. In both cases, same mobile phase is used.

what could be the reason?

thanks in advance

The most obvious answer is that the columns were not of similar resolving ability for that separation..

We would need a lot more details about the actual column sizes, particle sizes, loaded sample quantity, and mobile phase composition to make any meaningful comments..

In particular, for large columns, the samples are often pre-loaded onto silica and loaded into a module ahead of the column, and minor changes in that SIM procedure can affect the separation.

Bruce Hamilton

apart from bruce's comments, you also need to remember that these are low to medium pressure LCs.
especially for the pump the hardware used is not like for HPLC.
in both cases they use syringe pumps and depending on the model , the proportionning is done differently.

these differences affect:
flow precision- which is not pulse free at all and precision is a relative term over a period of time.
gradient formation and solvent mixing will be done differently and it will especially be affected in a separation where you have a sample cartridge used since they can come in different types and shapes.