Operation Tips and Some Details of Flash Column

Flash chromatography technology is developed since the year of 1978 and applied for the purification of the organic compound. In comparison with traditional column chromatography, flash chromatography is faster and cheaper.

If you are going to isolate a certain desirable compound, flash column chromatography is a good way to separate the different components of a mixture very effectively by using pressure in the column.

We all know that every component of a mixture has its own particular shape, size, polarity, and solubility. Those distinguishing characteristics can be used by scientists to isolate and purify each individual component within a mixture.

The isolation can be done in many ways, and the principle is the same as always. The affinity of certain molecules to others will slow down their movement through a medium while other molecules in the mixture can pass more easily through the medium. Then we can get clear separation and purification of the components from the mixture.

Chromatographic Silica Gel Flash Columns

Nowadays we can run the flash columns with compressed air pushing the solvent through the column. HAWACH flash columns will not only help you provide better separation but also save the running time of the separations.

Operation Tips:

  1. Sample Loading:
    • Ensure the sample is dissolved in a suitable solvent and properly loaded onto the flash column. Avoid overloading to prevent band broadening.
  2. Packing and Conditioning:
    • Pack the flash column with the appropriate stationary phase, ensuring an even bed. Condition the column with the chosen mobile phase before sample injection.
  3. Flow Rate:
    • Use an appropriate flow rate for the chosen column size. Too high a flow rate may lead to poor separation, while too low a flow rate can result in long run times.
  4. Monitoring:
    • Regularly monitor the eluent composition and fraction collection to track the progress of the separation.
  5. Gradient Elution:
    • For complex mixtures, consider using a gradient elution method to improve separation efficiency.
  6. Column Length and Diameter:
    • Choose the column dimensions based on the sample size and the level of separation required.
  7. Sample Concentration:
    • Concentrate the sample if necessary to improve detection sensitivity.
  8. Fraction Collection:
    • Use appropriate collection vessels and labels to accurately collect fractions for further analysis.
  9. Column Compatibility:
    • Ensure that the column material is compatible with the solvents and chemicals used in the separation process.
  10. Cleaning and Maintenance:
    • Regularly clean and maintain the flash column to prevent contamination and ensure consistent performance.

Some Details of Flash Column

In general, flash chromatography is the technology of normal-phase liquid chromatographic separation. Sometimes, it also uses reverse-phase silica gel as the filler. However, most of the users are inclined to use silica gel in flash chromatography.

Column packing consists of wet and dry two kinds. In general, the wet process is the most convenient way to dissolve samples with eluent, dichloromethane, ethyl acetate, and so on. The piston at the bottom of the column must not be coated with lubricant, otherwise, it will be brought into the eluent, and the valve of PTFE material can be used. There is no substantial difference between dry and wet packing, as long as the columns can be filled. The packed columns should be moderately tight and be sure to be uniform or the sample will flow diagonally from one side.

Generally, the volumes of sample loading range from milligrams to hectograms, and the flow rates are 10 ml/min to 300 ml/min. Mostly, flash chromatography uses the organic solvent with low and medium polarity as the mobile phase, such as hexane and ethyl acetate. Nowadays, most of the flash columns apply the technology of automatic loading and the column bedding is tight and uniform without the channeling effect. Also, the degree of separation is high and the reproducibility is good.

Furthermore, the normal-phase and reverse-phase silica gel fillers of different grain sizes (minimum 15μm) can make the users choose different flash columns according to different requirements of economy and efficiency.

In terms of the raw material for making the flash column, polypropylene of medical grade is a good choice because it avoids creating pollution to the separated sample. Besides, the transparent column allows the users to observe the condition of sample separation more directly.