HPLC method development

[ajey]

When & Why phenyl and silica columns to be used? and
What is the difference between phenyl and silica columns?
Regards,
Ajay

[tom jupille]

Silica columns are used for normal phase chromatography. Phenyl columns are used to provide alternate selectivity (versus the more common alkyl bonded phase columns such as C18) in reversed-phase.

The majority of HPLC columns use silica as the "substrate". "Silica" columns are just that: the bare silica gel. Most columns are "bonded phase" columns in which some moiety is chemically grafted to the surface of the silica. The most common bonded phases are C18, C8, phenyl, and cyano, but there are a wide variety of others available.