phenyl Column

[praveenpaliwal]

Hellow,

I have some confusion for phenyl HPLC column. If I have compound which contain two to three phenyl ring and when i inject it on phenyl column the molecule should eluted fast due to pi-pi interaction of phenyl ring with phenyl ring of column packing. But I observed the high retention and like dissole like process is prominenet. I want to know whatt is the mechanism of phenyl column against these kind of phenyl compounds. If any one have litrature please mail me.

Regards
Praveen

[Uwe Neue]

Phenyl columns are first reversed-phase columns, and give retention just as other reversed-phase columns. Next they give specific retention increments for analytes that interact via pi-pi interactions, or a lack of increment for analytes that do not have such specific interactions. Also, acetonitrile itself shows some pi-pi interactions, which suppresses some of the stationary phase effects.

Journal of Chromatography A, 1127 (2006) 161–174

[mohan_2008]

Phenyl ring compounds interact with the Phenyl ring part of the bonded hydrophobic moiety of the stationary phase via aromatic/pi-pi interactions predominantly. This will serve to increase the retention time of your phenylic compounds specifically- And not lower the retention. Just as seen in your case.

Phenyl ring offers a different selectivity in contrast to the traditional Carbon phase.

Hope it helps.

[Bryan Evans]

USP L11 - "Phenyl groups chemically bonded to porous silica
particles, 1.5 - 10um in diameter"

So, this list includes: phenyl phases with different alkyl chain linkers,
biphenyls, polar embedded linked phenyls, ect.

The propyl phenyl has retention similar to C4 + added pi-pi interaction.

[mohan_2008]

Generally -

Retention of solutes is a property of the Carbon load of the column.
And, technically hydrophobic compounds tend to elute faster on phenyl as compared to a traditional C18, the factor being carbon load.

However, aromatic or fused ring compounds with phenyl chains tend to stick to phenyl columns more than C18 and hence a distinction.