Chromatography Forum

Hi all,

I'm currently running purity and assay tests on an organic metal chelate (complexed with iron, 5 wt%). I'm using a C18 endcapped stationary phase and ACN/water mobile phase with TFA (gradient 5% --> 95% organic) combined with UV detection. However, I'm experiencing increase of area response and decrease of resolution over time. I was wondering whether this might perhaps be caused by stationary phase saturation/deterioration by iron over time?

Does anyone have experience with this problem or with analysis of organic metal chelates by RP HPLC in general?

Thank you for your response.

No matter how is your endcapping - double, 100% or best in the world, still there are free -SiOH groups on the surface and with your metal ions they are happy to bind and that will lead to the fact that you need to purchase a new column.
I would use another mode than RP18.
Good luck

Thank you for your response! Which alternative chromatographic mode(s) to RP C18 would you suggest?

IC could help. https://www.shodex.com/en/dc/07/04/06.html here maybe you will find some answers.