Monolithic Silica with Bimodal Pore Structure

Thanks to their patented monolithic silica technology, Chromolith® HPLC columns allow you to race through separations with maximum robustness and selectivity—at minimal back pressure.

  • Very high matrix-tolerance and long column life-time
  • Enables rapid separations due to very low column back pressure
  • High-throughput analysis with excellent separation efficiency and peak capacity

Chromolith® HPLC and UHPLC columns are made from monolithic silica with a bimodal pore structure using sol-gel technology. Mesopores and macropores are formed within the monolithic silica. The column is no longer packed with small particles but consists of a single monolithic piece of high-purity polymeric silica gel.

The mesopores form the fine porous structure within the solid silica in exactly the same way that they do within traditional silica particules. It is the mesopores which provide the high surface area of the silica and on this surface the separation takes place. The separation process itself is virtually the same with both particulate silica columns and with Chromolith® monolithic columns. Therefore, methods can easily be transferred between the two column types. The major difference between particulate and monolithic columns lies in the macropores. The very large 2 µm macropores give the columns very low backpressure and enable very fast analysis. The revolutionary bimodal pore structure of Chromolith® columns provides a unique combination of macropores and mesopores.

 

Silica monolithic HPLC column for low back pressure separations

Figure 1. Silica monolithic HPLC column for low back pressure separations

 

Speed-up Separations at low column backpressure

In practice, this means that separations can, for example, be two times faster at half the column backpressure compared to 5 μm columns. The macropores reduce column back pressure and allow the use of faster flow rates, thereby considerably reducing analysis time. The mesopores form a fine porous structure, which creates a very large active surface area for high-efficiency separations. Column re-equilibration between analyses can be performed very quickly at high flow rates.

HPLC back pressure vs flow rate for different columns

Figure 2. Column back pressure at different flow rates. Comparison of a Chromolith® Performance column, 100-4.6 mm vs. equivalent classical particulate HPLC columns.

 

Chromolith® Performance RP-18e 100-4.6mm

     
Column Chromolith® Performance RP-18 encapped 100-4.6mm
Mobile phase Isocratic acetonitrile / 0.1 % trifluoroacetic acid in water, 20/80 (v/v)
Pressure Total pressure (including HPLC) system 25°C
Detection UV 220 nm
Injection Volume 5µL
Sample Atenolol
Pindolol
Metoprolol
Celiprolol
Bisoprolol
63 µg/mL
29 µg/mL
108 µg/mL
104 µg/mL
208 µg/mL

Analysis speed

 

Figure 3. Analysis speed

 

With Chromolith® columns, flow rates can now easily be varied from 1 mL up to 9 mL per minute with the same high-quality resolution.  A mixture of five beta-blocker drugs was analyzed to demonstrate the extreme time savings and high separation efficiency made possible with Chromolith® columns. Due to excellent mass transfer properties of the monolithic skeleton, high-speed separation was possible, even at high flow rates. The beta-blockers were well separated with excellent peak symmetry.  At 9 mL/min, analysis time was less than 1 minute, and the column back pressure was only 153 bar.

 

Column Robustness and Matrix-Tolerance

The large macropores also provide a second unique benefit. Whereas particulate columns frequently get blocked or plugged by matrix-rich samples (e.g. food samples or biological samples), Chromolith® monolithic columns are very much more resistant to blockage. The reason is simple – the 2 µm macropore is not easily blocked by matrix material in the sample. This means that the amount of sample preparation required can be reduced, even for complex samples. Filtration through a 0.45 µm luer-tip filter is frequently the only sample preparation required, possibly with a protein precipitation step for biological samples.

Effect on time for HPLC and UHPLC separation

Figure 4. Effect on time for HPLC and UHPLC separation of matrix-rich samples when SPE is needed for UHPLC to extend the column lifetime

 

Column lifetimes are frequently many times longer than for particulate columns for the same analysis. Longer columns can also easily be used since the column backpressures are so low. This is achieved by coupling columns together, which gives very high theoretical plate numbers for separating complex multi-component samples.

 

Materials

Product Modification I.d. Length Content Ordering No.
Chromolith® Validation Kit RP-18e 2 mm 100 mm 3 columns from 3
different batches
1.52062
Chromolith® Performance RP-18e 2 mm 100 mm 1 UHPLC/HPLC column 1.52006
Chromolith® FastGradient RP-18e 2 mm 50 mm 1 UHPLC/HPLC column 1.52007
Chromolith® Flash RP-18e 2 mm 25 mm 1 UHPLC/HPLC column 1.52014
Chromolith® Guard Cartridge Kit RP-18e 2 mm 5 mm 3 guard cartridges,
1 cartridge holder
1.52008
Chromolith® Guard Cartridge RP-18e 2 mm 5 mm 3 guard cartridges 1.52009
Chromolith® Validation Kit RP-18e 3 mm 100 mm 3 columns from 3
different batches
1.52063
Chromolith® Performance RP-18e 3 mm 100 mm 1 HPLC column 1.52001
Chromolith® FastGradient RP-18e 3 mm 50 mm 1 HPLC column 1.52002
Chromolith® Flash RP-18e 3 mm 25 mm 1 HPLC column 1.52003
Chromolith® Guard Cartridge Kit RP-18e 3 mm 5 mm 3 guard cartridges,
1 cartridge holder
1.52004
Chromolith® Guard Cartridge RP-18e 3 mm 5 mm 3 guard cartridges 1.52005
Chromolith® Performance RP-18e 4.6 mm 100 mm 1 HPLC column 1.02129
Chromolith® Validation Kit RP-18e 4.6 mm 100 mm 3 columns from 3
different batches
1.51466
Chromolith® SpeedROD RP-18e 4.6 mm 50 mm 1 HPLC column 1.51450
Chromolith® Flash RP-18e 4.6 mm 25 mm 1 HPLC column 1.51463
Chromolith® Guard Cartridge RP-18e 4.6 mm 10 mm 3 guard cartridges 1.51452
Chromolith® Guard Cartridge RP-18e 4.6 mm 5 mm 3 guard cartridges 1.51451
Chromolith® Validation Kit RP-18e 4.6 mm 100 mm 3 columns from 3
different batches
1.52019
Chromolith® HighResolution RP-18e 4.6 mm 150 mm 1 HPLC column 1.52023
Chromolith® HighResolution RP-18e 4.6 mm 100 mm 1 HPLC column 1.52022
Chromolith® HighResolution RP-18e 4.6 mm 50 mm 1 HPLC column 1.52021
Chromolith® HighResolution RP-18e 4.6 mm 25 mm 1 HPLC column 1.52020
Chromolith® HR Guard Cartridge RP-18e 4.6 mm 5 mm 3 guard cartridges 1.52025
Chromolith® Performance RP-8e 4.6 mm 100 mm 1 HPLC column 1.51468
Chromolith® HighResolution RP-8e 4.6 mm 100 mm 1 HPLC column 1.52064
Chromolith® Guard Cartridge RP-8e 4.6 mm 5 mm 3 guard cartridges 1.52013
Chromolith® Phenyl 4.6 mm 25 mm 1 HPLC column 1.52056
Chromolith® Phenyl 4.6 mm 50 mm 1 HPLC column 1.52057
Chromolith® Phenyl 4.6 mm 100 mm 1 HPLC column 1.52058
Chromolith® Guard Cartridge Phenyl 4.6 mm 5 mm 3 guard cartridges 1.52059
Chromolith® CN 4.6 mm 25 mm 1 HPLC column 1.52046
Chromolith® CN 4.6 mm 50 mm 1 HPLC column 1.52047
Chromolith® CN 4.6 mm 100 mm 1 HPLC column 1.52048
Chromolith® Guard Cartridge CN 4.6 mm 5 mm 3 guard cartridges 1.52050
Chromolith® DIOL 4.6 mm 25 mm 1 HPLC column 1.53170
Chromolith® DIOL 4.6 mm 50 mm 1 HPLC column 1.53171
Chromolith® DIOL 4.6 mm 100 mm 1 HPLC column 1.53172
Chromolith® Guard Cartridge DIOL 4.6 mm 5 mm 3 guard cartridges 1.53175
Chromolith® Performance Si 4.6 mm 100 mm 1 HPLC column 1.51465
Chromolith® Guard Cartridge Si 4.6 mm 5 mm 3 guard cartridges 1.52011
Chromolith® Performance NH2 4.6 mm 100 mm 1 HPLC column 1.52028
Chromolith® SpeedROD NH2 4.6 mm 50 mm 1 HPLC column 1.52027
Chromolith® Flash NH2 4.6 mm 25 mm 1 HPLC column 1.52026
Chromolith® Guard Cartridge NH2 4.6 mm 5 mm 3 guard cartridges 1.52030
Chromolith® Guard
Cartridge Holder
- 4.6 mm 5 mm 1 cartridge holder 1.52032
Chromolith® Guard
Cartridge Holder
- 4.6 mm 10 mm 1 cartridge holder 1.52033
Chromolith® Column Coupler -     1 column coupler 1.51467