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immobilized stationary phase
Posted: Fri Aug 21, 2009 5:51 pm
by praveenpaliwal
In many chiral method development literature the word immobilized is used for stationary phase. What is immobilized stationary phase.
Best regards
Praveen
Posted: Fri Aug 21, 2009 6:05 pm
by grzesiek
"The immobilised products from Daicel consist of silica to which a derivatised polysaccharide polymer has been covalently bonded"
this is done to increase the stability of the column, later column were "coated" and so narrower range of solvents could be used and less presure was tolerated
usually there is the same chiral selector only the column is more stable
Posted: Mon Aug 24, 2009 7:43 pm
by praveenpaliwal
Sir,
the word narrower is used by u . What is the meaning of this word.
Praveen
Posted: Tue Aug 25, 2009 10:18 am
by grzesiek
sorry for my english, you have less oslvents to choose
please google Chiralpak AD and Chiralpak IA, first one is coated second immobilized, manuals will specify solvents you can use
Posted: Tue Aug 25, 2009 12:22 pm
by Fiz
Immobilized means that the chiral selector is chemically bonded to the silica. Except most Daicel materials all other chiral columns are typically "immobilized".
In case of Daicel only the "I" materials are the covalently bonded highly crystaline polysaccharides.
They might be slightly more stable than the "coated" one and are less limited in regards of the solvents. But usually they aren't that powerful than the coated one, although by using e.g. small amounts of chloroform the enantioseparation can be regained and selectivley changed.