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LC-MS flow rate max
Posted: Sun Dec 11, 2011 8:13 pm
by sofiane
HI
can you tell me about the maximum flow rate used in LC-MS
thank you
Re: LC-MS flow rate max
Posted: Mon Dec 12, 2011 12:10 am
by Jetjamnong
With a liquid chromatographic system (10 μl/min – 1000 μl/min) and with a syringe pump (0. 3 μl/min - 10 μl/min alone and 100 μl/min –1000 μl/min)
For ESI, avoid flow rates higher 500 μl/min using the ESI source due to loss of ionization efficiency in
the electro spray process itself. The highest ESI efficiency you will gain with flow rates below 200 μl/min.
Re: LC-MS flow rate max
Posted: Mon Dec 12, 2011 7:22 pm
by sofiane
but if we use API or APCI
I use a flow rate of 3 ml/min
can I do a LC-MS analysis
Re: LC-MS flow rate max
Posted: Tue Dec 13, 2011 10:26 am
by lmh
The flow-rate you can get away with depends on your instrument, and should be clearly stated in the instrument's specifications and in the help-files (which will tell you what source temperatures and gas flows to use for different flow-rates and sorts of ionisation). If your instrument can't handle the flow-rate you are using, then you can put a tee-piece before it and divert part of the flow to waste (or collect fractions for other analyses! You can use a proper flow-splitter, or a tee and some sort of restriction (perhaps just a bit of tubing) to set a sensible split-ratio). In many cases the measurement is concentration-dependent, not total-material-dependent, so there won't be any loss of sensitivity. (You can also, of course, get a narrower column and scale everything down.)