I am currently developing my SOP for sample injection into our soon-to-arrive Biorad Aminex HPX-42A column. The plan is to use HPLC grade water at 85°C for eluent. Based on the "Use and Care" guidelines provided for the columns, the HPX-42A has an acceptable pH range of 6-8. However, we intend to inject samples with a pH as low as 2. I would like to carry out neutralisation on the samples, but want to ensure that I am not causing any issues with my neutralising agent selection.
Are their limitations for neutralising agent use in samples to be injected into Aminex columns?
I am aware that there's a potential problem with counter ion replacement in these ligand exchange columns - if the cation that could exchange with the silver is in salt form, does this still pose a risk?
With a refractive index detector, there's a potential for eluent density fluctuation with salts that remain in the solution. Should I therefore use a neutralising agent whose salts precipitate? (Barium Hydroxide?)
Any suggestions or comments would be appreciated.
This column is commonly used for carbohydrate analysis. In order to prevent column striping, the samples should be neutralized beforehand (you can use a pH meter and later 0.05 N HNO3 or NH4OH). Much later, you will have to replace the Silver by using a dilute solution of Silver Nitrate.
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