The basis for reproducible chromatography in laboratory and production preparative column
chromatography is consistent sample and chromatographic variables. One of the most difficult
variables for a user to control is of course the stationary phase.
In practice, standardized sorbents are required. These will provide a high degree of method
reliability, direct transfer from analytical scale and allow carefully optimized throughput
per unit of time.
Only silica gels with a defined pore structures and reproducible trace component profiles
fulfill the requirements of chromatography.
EMD Chemicals has specialized, for decades, in the manufacture of standardized
silica gel packing materials for preparative chromatography and offers a wide range of customized
sorbents. The product range is extensive with several special types, e.g. silica gels such as
LiChroprep® to high purity acid-washed silica gels. |
 |
EMD gels provide the user with unique diversity of methodology: Regardless of which
chromatographic process is used (DC, TLC, HPTLC, HPLC, preparative chromatography), direct and
rapid transfer to a production scale is guaranteed and with minimized risk. This is ensured by
the fact that common base raw materials are used for all stationary phases, thus providing
identical chromatographic selectivity.
In order to be able to achieve this goal, EMD produces all silica gel 60 packing materials
for analysis, pilot plant processes and production using the same silica gel raw material
which has specified surface area and a defined specific pore volume and pore size distribution.
Once a particular silica gel raw material has been tested with respect to its suitability
for pore structure, specific pore volume, specific surface, chemical purity and other requirements
for chromatography, it is classified into defined particle size ranges.
These particle size ranges are selected to optimize the separating performance and permeability
results for the chromatographic process used (DC, TLC, HPTLC, HPLC, preparative chromatography).
Thus, once a successful separation has been found at the analytical scale, it can be transferred
rapidly to pilot plant or production scale (see illustration below).
EMD standardized Silica Gels thus offer direct scale-up without
compromise and without lost time.
The selectivity of EMD's silica gels for analytical and preparative applications is identical.
Resolution, however, decreases, according to theory, with increasing particle size. Improved
separation can be achieved at the expense of longer retention times and if the selectivity of
the entire system is optimized using different mobile phases.
EMD Quality: customized without compromise, for a high degree of reliability in
production.
Experience has shown that for chromatographic separations in production,
silica gel 60 i.e. silica gels withf a mean pore size of 60Å and
in particle size ranges 40-63µm and 63-200µm are precisely suited
to the separation of complex mixtures.
| Specifications |
| |
Silica Gel 60
(40-63µm) |
Silica Gel 60
(63-200µm) |
| Catalog Number |
9385 |
7734 |
| Particle Size Range (µm) |
40-63µm |
63-200µm |
| Mean Particle Size (µm) |
~50 |
~105 |
| Specific Surface Area (m2/g) |
~500 |
~500 |
| Specific Pore Volume (ml/g) |
0.70-0.78 |
0.71-0.78 |
| Mean Pore Size (Å) |
60 |
60 |
| pH (10% aqueous suspension) |
7+0.5 |
7+0.5 |
| Loss on Drying (%) (3 hours/120°C) |
<9 |
<7 |
| Bulk Density (g/ml) |
~0.45 |
~0.45 |
| Back Pressure (bar) (column 250-4, n-heptane, 20ml/min) |
~2 |
~0.5 |
| Iron (%) (acid extraction) |
<0.02 |
<0.02 |
| Chloride (%) (acid extraction) |
<0.02 |
<0.02 |
| Theoretical Plates (N/m)* |
~3000 (anisole) |
~1000 (anisole) |
| Relative Retention Alpha* |
~1.73 |
~1.73 |
* 2-nitroanisole/4-nitroanisole
|
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