Chromatography Forum

Hello, I have taken over method development project from a colleague(he has left the company)...and i need some help.
The work he has previously done was on LCMSMS. he has given me a brief description:
Ionisation mode: negative
Column:Phenomenex Aqua C18-50mm x 2.0mmx 5μm
Buffer: Water and acn with 0.1% formic acid and 5mM ammonium formate.

From the data above what does he mean by ionisation mode mean? and the formic acid is to adjuct pH and the ammonium is the buffer to retain pH?

Ionisation mode: negative
Column:Phenomenex Aqua C18-50mm x 2.0mmx 5μm
Buffer: Water and acn with 0.1% formic acid and 5mM ammonium formate.

what does he mean by ionisation mode mean?

The ionization mode is the method for converse (ionize) the analyte(s) from neutral molecul to charged molecul (m/z).
For example, the analyte molecul is C13H18O2 (M = 206),
Negative mode : M-H (m/z = 205) and this is Molecular ion in Negative charged (it's called de-protonated ion)
Positive mode : M+H (m/z = 207) and this is Molecular ion in Positive charged (it's called protonated ion)
However, you can select or setting up ionization mode on the LC/MS/MS programe.

and the formic acid is to adjuct pH and the ammonium is the buffer to retain pH?

Yes, that's right. may be this is provided you pH 3-4.

Best Wishes
Jetjamnong