HPLC Columns for Small Molecules

Most drugs are small molecules. The upper molecular weight limit for a small molecule is approximately 800-1,000 Daltons which allows for the possibility of diffusing across cell membranes. Reversed phase is the most popular liquid chromatography separation mode for small molecule analysis. Another separation mode, HILIC is gaining popularity, especially when coupling with mass spectrometers as the detector. Ion-exchange, ion-pairing, size-exclusion, and mixed-mode HPLC columns are suitable in certain applications.

Reversed-Phase HPLC Columns

The separation mechanisms of the reversed-phase HPLC generally include three modes of retention,
- Electrostatic interaction (silanol activity / hydrophillic endcapping)
- hydrophobicity (ligand chain length)
- steric selectivity (ODS ligand density)

Within reversed phase HPLC columns, some of the most popular stationary phase are C18, C8, C4...etc. Of these, C18 is the most dominant HPLC columns used vertually in every small molecule labs. There are also variations developed to better analyze subsets of small molecules. For example, 100% aqueous, polar-embedded phases, high carbon load...etc.

Reversed Phase Chromatography
2μm and sub-2μm HPLC Columns
ES Industries Epic C18
ES Industries Epic Polar
ES Industries Epic PFP-LB
Dikma Endeavorsil C18
MN Nucleodur Gravity C18
MN Nucleodur Gravity C8
MN Nucleodur Isis C18
MN Nucleodur Pyramid C18
MN Nucleodur Sphinx RP C18

HILIC
ES Industries Epic Diol HILIC
ES Industries Epic HILIC FL
ES Industries Epic HILIC-HC
ES Industries Epic HILIC PI
ES Industries Epic Silica HILIC
MN Nucleodur HILIC

2μm and sub-2μm HPLC Columns
Reversed-Phase
ES Industries Epic C18
ES Industries Epic Polar
ES Industries Epic PFP-LB
Dikma Endeavorsil C18
MN Nucleodur Gravity C18
MN Nucleodur Gravity C8
MN Nucleodur Isis C18
MN Nucleodur Pyramid C18
MN Nucleodur Sphinx RP C18
HILIC
ES Industries Epic Diol HILIC
ES Industries Epic HILIC FL
ES Industries Epic HILIC-HC
ES Industries Epic HILIC PI
ES Industries Epic Silica HILIC
MN Nucleodur HILIC
Ion-Exchange
ES Industries Epic SCX
ZirChrom Z-APPS (zirconia-based)