In this case I think the striping agent should bind to the resin stronger than the analyte or the eluting agent should bind with the metal strongly and detach from the resin. Usually increasing salt concentration (may be not good with HPLC without some kind of desalting step) might be a possibility for elution. Or a metal chelating reagent such as EDTA, histidine can be used.

More details are needed

Is it anion or cation exchage

are you HPLC followed by what type of detector, icp- ms, conductivity, etc

There are many factors should be taken in consideration like the type and the concentration level of the analyte (cation or anion), the matrix, the type of the resin, chromatographic conditions, and the type of the detector used. You need to make an optimization using synthetic sample before the real one.

Hello, 

It and anion exchanger. 

detection is  by DAD or  PDA

Thank you

Hi Simon

Heavy metals do not normally give very good signals for UV or VIS spectrophotometric techniques, unless they are complexed, but this is not to say It cannot be done

On the other hand, I would follow the resin manufacturer recommendations for eluting your metals form the anion resin, since all manufacturers have slightly different formulations on the anion resin giving properties such as strong, weak, etc anion affinity.

The manufacturer is definitely the best source for knowning conditions on their products for specific applications, I would trust them unless you have tested your own specific conditions and can prove otherwise