Does ammonium fluoride assist ionisation? (and how?)

Hi I recently read a report in which 1mM ammonium fluoride was added to the LC-MS mobile phase to increase sensitivity/ionisation. Can anyone verify this is effective for ESI positive mode analysis of drugs? Can you point me to a reference that describes how this works (if it does) 

Cheers

Peter

Parents
  • Addition of NH4F would changed process of ionisation, but 1mM mentioned in the app note seems to be a lot. I am using 0,2mM NH4F, in Santa Clara are using even less. Addition of formic acid or acetic acid (about 20-50uL into 1L) would stabilise retention times. Using of pure NH4F usually reulted in cloged column, addition of acid really helped.

    Ammonium fluoride would help you with a response of many problematic analytes (phenols, phenoxy acids), it is helping in both, positive and negative ESI. It is not good for every compound, but it is very good for majority of small molecule analytes I ever tested (pesticides, pharmaceuticals, mycotoxins, alkaloids, lipids, polyphenols...).   

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  • Addition of NH4F would changed process of ionisation, but 1mM mentioned in the app note seems to be a lot. I am using 0,2mM NH4F, in Santa Clara are using even less. Addition of formic acid or acetic acid (about 20-50uL into 1L) would stabilise retention times. Using of pure NH4F usually reulted in cloged column, addition of acid really helped.

    Ammonium fluoride would help you with a response of many problematic analytes (phenols, phenoxy acids), it is helping in both, positive and negative ESI. It is not good for every compound, but it is very good for majority of small molecule analytes I ever tested (pesticides, pharmaceuticals, mycotoxins, alkaloids, lipids, polyphenols...).   

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