Why would a new SFC column with a bonded ligand (such as 2-EP) show longer retention compared with a used, older column of the same part number? - WKB233714

ENVIRONMENT

• Supercritical Fluid Chromatography (SFC)
• Viridis columns
• UPC2
• Retention characteristics

ANSWER

New SFC columns with a bonded ligand, such as 2-ethylpyridine, tend to have more ligand compared to older, used SFC columns.

ADDITIONAL INFORMATION

There are many possible reasons why a new SFC column exhibits longer retention than a used column of the same part number.

A common cause is that old, used columns have lost ligand as a result of hydrolysis (due to exposure to proton donor solvents, such as methanol, over time). 

As a column loses ligand, the surface becomes less and less polar (less retentive).

Then, upon installation of a new SFC column of the same part number, you may observe longer retention in the new column, because it has more ligand when it is new.