Microcolumns

Introduction to Microcolumns

Microcolumns are a natural progression from pipette filtrations, with microcolumns having the addition of a chemically active material in the pipette Phaih typically removes unwanted impurities. The technique is also related to solid phase extraction and is often a less expensive alternative. The technique is in many ways a simplified version of column chromatography, relying on the same underlying theory, but carried out in a simplified (and much quicker) approach, although with a much more limited scope of use.


Use

Microcolumns are suitable for small scale purification where the impurities are fully adsorbed onto the packing material, and the compound(s) of interest freely elute in the combination of packing material and solvent chosen. This technique is often used as a final purification before analysis, especially for HPLC and GC, where this technique can be viewed as a method to protect the columns from becoming blocked or damaged with material which won't elute. It is usual to collect all the eluent from a microcolumn as a single fraction. If multiple fractions are desired, performing flask column chromatography is recommended.


The majority of microcolumns use silica gels for column chromatography in normal phase. They are particularly useful for removing very polar materials which get stuck to the top of the microcolumn, allowing the desired products to elute. It may be desirable to carry out a TLC analysis of the material to be purified first. Ideally high Rf values are required for the compounds of interest, and the impurities want to be baseline. The lower the Rf for the desired compound(s), the more solvent required in order to ensure total elution.


Packing materials

Normal phase (polar)

Reversed phase (non-polar)

Miscellaneous