FAQs

Solid sample loading is a useful technique to load the sample to be purified onto a column, particularly for samples of low-solubility. In this case, iLOK flash cartridge is a very suitable choice.
Generally, the sample is dissolved in a suitable solvent and adsorbed onto a solid adsorbant which could be the same as used in flash columns, including diatomaceous earths or silica or other materials. After removal / evaporation of the residual solvent, the adsorbent is put on top of a partly filled column or into an empty solid loading cartridge. For more detailed information, please refer to the document iLOK-SL Cartridge User guide for more details.

Column volume is approximately equal to dead volume (VM) when ignoring the additional volume in the tubings connecting the column with the injector and the detector.

Dead time (tM) is the time required for elution of an unretained component.

Dead volume (VM) is the volume of the mobile phase required for elution of an unretained component. Dead volume can be calculated by the following equation:VM =F0*tM.

Among the above equation, F0 is the flow rate of the mobile phase.

No, end-capped silica is insoluble in any commonly used organic solvent.

The silica flash columns are disposable and for single use, but with proper handling, the silica cartridges can be reused without sacrificing performance.
In order to be reused, the silica flash column needs to be simply dried by compressed air or flushed with and stored in isopropanol.

Proper storage will allow C18 flash columns to be reused:
• Never allow the column to dry out after using.
• Remove all organic modifiers by flushing the column with 80% methanol or acetonitrile in water for 3 – 5 CVs.
• Store the column in the above mentioned flushing solvent with end fittings in place.

For the large size columns above 220g, the thermal effect is obvious in the process of pre-equilibrium. It is recommended to set the flow rate at 50-60% of the suggested flow rate in pre-equilibrium process to avoid obvious thermal effect.

The thermal effect of mixed solvent is more obvious than single solvent. Take the solvent system cyclohexane/ethyl acetate as an example, it is suggested that use 100% cyclohexane in the pre-equilibrium process. When pre-equilibration is completed, the separation experiment could be performed according to the preset solvent system.

For SepaFlash^TM Standard Series columns, the connectors used are Luer-lock in and Luer-slip out. These columns could be directly mounted on ISCO’s CombiFlash systems.

For SepaFlash HP Series, Bonded Series or iLOKTM Series columns, the connectors used are Luer-lock in and Luer-lock out. These columns could also be mounted on ISCO’s CombiFlash systems via extra adaptors. For the details of these adaptors, please refer to the document Santai Adaptor Kit for 800g, 1600g, 3kg Flash Columns.

The parameter column volume (CV) is especially useful to determine scale-up factors. Some chemists think the internal volume of the cartridge (or column) without packing material inside is the column volume. However, the volume of an empty column is not the CV. The CV of any column or cartridge is the volume of the space not occupied by the material pre-packed in a column. This volume includes both the interstitial volume (the volume of the space outside the packed particles) and the particle’s own internal porosity (pore volume).

The alumina flash columns are an alternative option when the samples are sensitive and prone to degradation on silica gel.

The back pressure of flash column is related to the particle size of packed material. The packed material with smaller particle size will result in higher back pressure for the flash column. Therefore the flow rate of the mobile phase used in flash chromatography should be lowered accordingly in order to prevent the flash system from stop working.

The back pressure of flash column is also proportional to the length of column. Longer column body will result in higher back pressure for the flash column. Furthermore, the back pressure of flash column is inversely proportional to the ID (internal diameter) of the column body. Finally, the back pressure of flash column is proportional to the viscosity of the mobile phase used in flash chromatography.

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