Answer / bhupalreddy

In chromatography silanol groups (Si-OH) at the
surface of silica gel are reacted with substituted Chloro
Silanes.

CH3 CH3
| | | |
--Si–OH + Cl - Si--R → --Si-O - Si - R
| | | |
CH3 CH3

By changing characteristics of group i.e. from changing R
from C1 to C18 we can alter the nature of stationary phase
from polar to non polar. Since C18 columns is non polar.
This helps separating various combinations of polar – non
polar constituents from the analyte.
C-8 columns contain 8 carbons and C-18 contains 18
carbons are attached to silicon group to form stationary
phases for chromatography. The C-18 columns are highly
Non polar compared to C-8 columns and most of the compounds
are well separated in C-18 carbon packed columns.

Answer / kumar nagendra karapala

C-8 means having 8 carbons and C-18 (ODS) means having 18
carbons both are attached to silicaon groups to from
stationary phases for Chromatography.

Answer / srikanth

C18 column is more hydrophobic than C8.
Because, The difference between the two columns will be in
the length of the carbon-chain attached to the silica
surface. Acoordingly C8 hplc columns have packing material
composed of silica particles attached to C8 carbon units
while C18 will, of course, have packing materials coated
with C18 hydrophobic units. Categorically both are reversed
phase but C18 columns will definitely be more "hydrophobic
rather than the C8 columns.

Answer / srinivas

in c18 column octa dacale silane is present and in c8
column octa silane is present

Answer / s.goutham

the c18 coloumn wsa highly non polar compared to c8
coloumn.Most of the compound well seperated in c18

Answer / apparao

Onaly differance is packing of coloumn

Answer / yojana

Onaly differance is packing of coloumn

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