Chromatography Forum

Hello,


I am trying to convert an LC-UV method to an LC-MS method in order to improve sensitivity. The problem is the original analyte is a chelator, and so the LC-UV method used EDTA in the mobile phase. Here are the mobile phase parameters:

65:21:14 0.01M phosphate buffer (pH 3.0):Methanol:ACN with 2mM EDTA
Discovery HS F5, 250mm*4mm, 5um, 40 deg C
Flow rate 1mL/min

This procedure is cited in Journal of Pharmaceutical and Biomedical Analysis 43 (2007) 1343-1351, Development and validation of HPLC-DAD methods for the analysis of two novel iron chelators with potent anti-cancer activity, by Mrkvickova et al.

The compound I am analyzing is also a chelator.

I'm aware of the issue with phosphate buffer in MS so I am going to select a different buffer. However, my main issue is trying to replace the EDTA. I've used heptafluorobtyric acid as an MS-friendly ion pair reagent in the past, can it be used effectively as a competitor for chelation (like EDTA) so that my analyte doesn't pick up an ion?

Thanks,

Chris

From an old 'chromforum before it was chromforum' thread...

http://www.lcresources.com/discus/messa ... 20021239pm

Chris Pohl suggested acetylacetone, but with no chromatographic experience with the compound.

Just to add, some chelators can be very labile for MS detection. Especially such compounds as Triapine (3AP) and the like. For these, refining the HPLC-UV method can yield great improvements.

Kerri