The 2mm I.D. semi-microbore columns of C18
phases are available in the COSMOSIL series. Compared with 4.6mm
I.D. columns, the semi-microbore columns are 5 times more
sensitive and reduce the solvent consumption by 80%.
The COSMOSIL semi-microbore columns perform best when used with
micro analysis HPLC equipment including tubing, injector and
detector cell.
The semi-microbore columns can replace existing COSMOSIL
analytical columns. Available packing materials are C18-MS,
C18-AR-II and C18-AR-300.
Please consult the table and the applications below for selection
guidance.
Material characteristics
5C18-MS-II
5C18-AR-II
5C18-AR-300
Silica gel
high purity spherical porous silica
Average particle size
5µm
Average pore size
approx. 120Å
approx. 300Å
Specific surface area
approx. 300m2/g
approx. 150m2/g
Stationary phase
monomeric type
polymeric type
End capping treatment
near-perfect treatment
Carbon content
approx. 16%
approx. 17%
approx. 12%
Sample load capacity
Sample load capacity is proportional to the cross section of the
column. Since the cross section of a 2mmI.D. column is about 1/5
that of a 4.6mmI.D. column: the optimum sample load is 1/5 that of
the analytical column.
In the example for naphthalene separation below, the theoretical
plate number of a 4.6mmI.D. column starts decreasing at 10µg of
the sample load; for the 2mmI.D. column the decreasing point is 2µg.
Dead volume greatly affects the semi-microbore column
performance.Use of a micro injector is highly recommended. In
order to avoid peak broadening, the injection volume should be
less then 1.0µl.
Recommended operating procedures
1.Flow rate must be less than 0.2 ml/min.
2.Pressure must be less than 15.0MPa
3.Filter solvents and samples with 0.5µm filters.
4.When you use a conventional HPLC system,the theoretical plate
number may be lowered by about 30%
5.Use of micro analysis HPLC equipment including tubing,injector
and detector cell is highly recommended.
Comparison with 4.6mml.D. column
The COSMOSIL semi-microbore columns are taking over the high
performance of COSMOSIL series.
The semi-microbore columns can be used in the same applications of
other analytical COSMOSIL columns.
:4.6mm
I.D. column 
: 2.0mm I.D.
Cosmosil 5C18-MS-II column
