The purpose of preparative chromatography is to obtain a high-purity single-component from the mixture. Unlike analytical chromatography, when selecting a mobile phase, separation operations such as subsequent solvent removal (rotary evaporation, freeze-drying, etc.) should also be considered. In general, highly toxic solvents should not be used, and multi-component solvents should be used as little as possible, and the purity of the solvent should also be considered. Here we introduce the mobile phase selection for separation and purification by preparative chromatography.
Commonly used normal phase and reversed phase mobile phases
| Reversed mobile phase | Normal mobile phase |
| methanol + water | n-hexane + isopropanol, n-butanol, propanol and other regulators |
| Acetonitrile + Water | n-hexane + ethyl acetate |
| tetrahydrofuran + water | Cyclohexane, petroleum ether |
Volatile substances should be selected for mobile phase additives
Acidic substances: usually add volatile acids such as TFA, formic acid, acetic acid, etc., the volume ratio is about 0.1%.
Neutral substances: it is best not to add, or you can add <20mm ammonium formate or ammonium acetate (can be removed by rotary evaporation).
Alkaline substances: add ammonia, diethylamine or triethylamine to adjust pH.
Mobile Phase Application Requirements
| High purity and little interference |
| Low boiling point, easy post-processing |
| Miscible with compounds (note the order of addition) |
| Matched to the detector (no absorption) |
| Matched to the detector (no absorption) |
Difficulties in the Development of Preparative Chromatography Purification Process
- Selection of suitable fillers
- Development of mobile phase method
The development of the mobile phase method is as important as the selection of the packing material. The method optimization process is repetitive and tedious. The development of a good preparation process requires the support of rich preparation experience. Welch Materials Separation and Purification Technology Laboratory can provide you with separation and purification process development services.
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