By jean paul on Friday, May 28, 2004 - 09:30 am:
Maybe you can try an other type of column, read the example of glutathione in J Chromatogr B
STEGHENS JP., FLOURIE F., ARAB K., COLLOMBEL C.
Fast liquid chromatography-mass spectrometry glutathione measurement in whole blood: micromolar GSSG is a sample preparation artifact.
J Chromatogr B, 2003, 25, 798(2):343-9.
By MG on Tuesday, June 1, 2004 - 06:36 am:
If you are using positive ion mode, the TFA may be okay, depending on the detection limit you need, but you will get more sensitivity with acetic or formic acid. I admit that I also try to avoid TFA use when possible. An alternative for retention of polar compounds is hydrophilic interaction chromatography (HILIC). Search the forum and you'll find several discussions of HILIC.
By David Batchelor on Thursday, May 20, 2004 - 07:36 pm:
I need to transfere a HPLC assay for a tripeptide (gly-pro-Glu) from a standard hplc with uv detection to an HPLC/MS method.
The current technique uses a acetonitrile/0.1%TFA gradient on a phenomenex aqua Synergi Hydro RP column. However when try to change the conditions to a MS compatable acid (acetic or formic) the GPE fails to bind. Does any on know or suggest an alternative stratgy.
Thanks