Chromolith® HPLC and UHPLC columns are made from monolithic silica with a bimodal pore structure using sol-gel technology. There are no silica particles.
Several key benefits result directly from the bimodal pore structure of the silica gel, which has 2 µm macropores and 13 nm mesopores:
The columns are available not only with octadecyl (RP-18e) or octyl (RP-8e) endcapped surface modification, but also with Phenyl, CN (nitrile), Diol and NH2 (amino) surface modification as well as an unmodified pure silica.
The internal diameters of the analytical columns are 2 mm, 3 mm, 4.6 mm and guard column cartridges with holders are also available. Chromolith® SemiPrep and Prep columns (10 mm and 25 mm I.D.) are also available as well as Chromolith® CapRod® capillary columns.
The mesopores of the silica gel in all Chromolith® columns are 13 nm, which gives a high specific surface area of 300 m2/g and good retention of the analytes.
Chromolith® UHPLC columns are Chromolith® columns with 2 mm internal diameter. These columns are ideal for use with UHPLC or UPLC instruments, thanks to their very small internal volumes. A particular benefit is again the very fast analysis, reduced sample-preparation and the low column backpressure.
Figure 1.Electron-Microscope photo of monolithic silica structure.
The silica itself is high purity, type B silica for inertness, reproducibility and stability, with modern bonding processes that optimize bonded phase coverage and maximize stability, while minimizing bleed and unwanted secondary interactions.
Chromolith® HighResolution (HR) columns are also available with the benefit of increased efficiency, very good peak symmetry and low column backpressure.
These have smaller 1.15 µm macropores, which significantly increase the separation efficiency (theoretical plate number) of the columns. The efficiency is approximately equivalent to 2.6 µm particulate columns whereas the backpressure is approximately equivalent to 5 µm columns.
Figure 2.Chromolith Column Separation
Chromolith® HPLC and UHPLC monolithic silica columns are cladded in inert PEEK (polyetheretherketone) polymeric material and can be connected directly to HPLC, UHPLC or UPLC system as a “ready to use” column.
Figure 3.Chromolith Column