Chromatography Forum

I have googled this question but I can't seem to find any answers. Can anyone tell me if using sub 50uL/min flow rates will improve the ionization efficiency? Are signal increases through low HPLC flow rates due mostly to chromatographic improvements or does the actual precentage of molecules ionized increase when there is a lower flow to mass spec? Also does microflow decrease signal lost due to matrix ion suppression?

Edit: I know that there have been studies demonstrating nanoflow improving ionization efficiency, but I haven't seen any about microflow

Hi HPLCLove

I'm sure someone will correct me if I'm wrong, but:

My understanding is that a microbore columns (~ 1mm internal diameter) have several advantages with respect to sensitivity. The first is the fact that your analyte is diluted less by the mobile phase in comparison to larger diameter columns. This means that the on-column concentration is greater to start with.

Regarding ionisation, slower flow rates in general allow for a more efficient desolvation process in ESI sources - i.e it is a more efficient desolvation process, as you have suggested. Combined with highly efficient peaks, you would expect to have a clear improvement in your signal intensity.

Bear in mind that narrow columns are more prone to band broadening, and greater consideration has to be applied to the 'amount' of analyte loaded on to the column.