Split flow. Do I need it?

[slentz]

I am running an assay on LC?MS. In order to speed up run times I want to run with a higher flow rate of 0.6ml/min. I am splitting the flow and of coarse my area peak counts are much smaller.

What I want to know is if it is necessary to split my flow?

Thanks

[Uwe Neue]

In order to understand, whether splitting does you any good, you can get a definitive answer only by looking at the signal-to-noise ratio. With UV, you can tell even without experimenting that there is no benefit. With MS, the story is more complicated, but as long as you stay within the recommended range of your MS, the data that I have seen do not indicate that there is a benefit to splitting.

The simple thing is to go and try it out. But be sure that you measure signal to noise, and not peak area. Peak area becomes smaller, when you increase the flow, even with UV detection.

[BillW]

Whether you need to split the flow will be instrument dependent. It will not usually result in sensitivity loss with MS, because it is a concentration-dependent technique.

Consider reducing the column bore diameter. This will both remove the issue with the split, and save alot of solvent.

[alpesh]

you can use 2.1 mm ID column or even smaller than this in MS. this will save lot of time and solvents. you dont have to split or reduce flow rate as well.