Chelators in LC-MS

[chris_singleton]

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

[bisnettrj2]

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.

[kerri]

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