Chromatography Forum

I'm running some compounds on the LC-ICP-MS to test if the compounds can be used as standards for my samples. One of my compound is a metal coordination complex, and I get two separate peaks on the LC-ICP-MS when I run it. I'm wondering if this is a general problem with metal coordination compounds or specific to this compound I'm testing. I thought maybe the compound is breaking down for whatever reason, but this compound doesn't degrade with light or at room temperature (my LC is set at 30'C). Do anyone have experience on running metal complexes on LC-ICP-MS (or LC-MS) and had multiple peaks showing up for a single complex?

Are you sure you have only one complex, not a mix of two isomers that are separated? There may be many reasons for the two peaks. There is not enough info in your message to make suggestions.

I recently developed an LC-MS/MS method for cyanocobalamin and hydroxocobalamin (vitamin B12 compounds which are metal complexes). Cyanocobalamin gives 1 peak, hydroxocobalamin gives 2 peaks no matter which parameters change. My best explanation for this behavior is that it exists as HO-cobalamin and H2O - cobalamin, giving the same MRMs.

This is not the general explanation you're after, and I'm quite sure there is no such thing. Just saying it's possible, even with more selective detection (MS/MS versus ICP-MS).

If you have 2 rather nice peaks that are separated for the same compound, it means that the compound does not gradually degrade, or change forms during your method. If it was the temperature of the column, for instance, you would get a peak with a tail, not 2 peaks. Either the compounds exists in 2 forms in the solution you're injecting, or you have a peak splitting problem related to the injection (mismatch injection solvent and starting mobile phase composition).