April 17, 2021, 10:58:27 PM
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Topic: ESI MS on Boc-amine  (Read 111 times)

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Offline tricyclic

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ESI MS on Boc-amine
« on: March 22, 2021, 06:58:52 PM »
Do you normally see the [M+H] on secondary Boc-amine under LC-ESI MS? I have hard time seeing it, but by NMR it should be the Boc-amine structure. Should I increase the acidity of the mobile phase? Should I increase the temperature of the probe to thermally cleave the Boc to see the free amine + H? Thanks!

Offline MOTOBALL

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Re: ESI MS on Boc-amine
« Reply #1 on: March 25, 2021, 02:22:45 PM »
Do you see [M+H] minus C4H8 or some other ?
Perhaps HOCOC4H9?

If you are using trifluoroacetic acid, this gives very strong ion pairs MH pos CF3 COO neg that are neutral.
Might have to switch to formic acid.

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