Some Tips About Reversed-Phase Flash Columns
The reversed-phase principle
The reversed-phase filler is a non-polar filler of C4, C8 and C18 aliphatic chain bonded on the silica gel matrix. And when the samples flow through the column, nonpolar or hydrophobic compounds are retained strongly, while polar samples are retained weakly and pass through the column bed more quickly. The “Reversed-phase” is used to describe the chromatographic process, which is just the opposite of normal phase chromatography.
1. Determine the dry, solvent-free weight of the samples that you need to separate.
2. Determine the sample for the column by using TLC. If the sample is complicated, this may not be possible.
3. Determine the method of application to the column, and the appropriate silica gel to compound ratio. Easy separation needs ratios of 30-50:1 (by weight), while harder separations require ratios of up to 120.
4. Pick the proper column. The amount of silica gel needing to use is determined by the size of the column. The best way to select the proper column for a given amount of silica gel is to consult us or instruction notes.
Once you have selected a column, you need to plug the stopcock end to avoid the drainage of silica. This is normally done with a small piece of cotton or glass wool or a long glass rod and so on. Carefully add your compound to the column, fill the column with the clue, close the stopcock and put the first tube under the column outlet. Once you have filled the column with samples, you are ready to operate the column.
Reliable and Reproducible
Hawach flash columns are precision-packed for high resolution as well as reproducibility. It features a one-piece design with Luer end fittings for easy connection to diverse chromatography systems. Hawach constantly pursues top technology to improve consumer feeling, for example, automatically detect the column type and size, and programs a default method, which can greatly reduce setup time and the potential errors in operation. A special chromatography technique uses compressed gas or a pump to make solvent pass flow through the column smoothly. As opposed to conventional gravity flow, Hawach flash column allows for faster flow rates and give special consideration for the stationary phase such as silica gel in the usage of finer particle size.
Versatile and Safe
Hawach flash columns are available in extra thick walls and cartridge pressure for safe operation. Flash column are all-welded end fittings ensure the column is able to withstand the pressure stability and not leak valuable compound. A wide offering of TLC plates makes operation easy, and delicate stationary phases expand the utility of the flash column. Moreover, high-quality media is specified for high resolution and reproducibility for high standard purification.
The selection of the mobile phase
The commonly used mobile phases are water with acetonitrile or water with methanol, occasionally water with tetrahydrofuran. Generally, we can add some weak acids or weak bases to adjust the liquid systems to partial acids or alkalis, which makes sure that the components can peak.
The commonly used weak acids are formic acid, trifluoroacetic acid. And the commonly used weak bases are ammonia water, ammonia bicarbonate, etc. The percentage added is generally the same as that in liquid systems.
A sampling of reversed-phase flash columns
In general, liquid phase wet sampling is used. Commonly used solvents include water, methanol, tetrahydrofuran, acetonitrile, NH-dimethylformamide, dimethyl sulfoxide.