Flash Reversed-Phase Column
The reversed-phase filler is a kindly of nonpolar filler such as C4, C8, C18 aliphatic chain which is bonded on the silica gel. Nonpolar or hydrophobic compounds are strongly reserved, while polar samples are weakly reserved and go through the flash reversed-phase column faster. The chromatographic process of “reversed-phase” is just the opposite of normal-phase chromatography.
The Selection of Mobile Phase
Commonly we use water and acetonitrile or water and methyl alcohol as mobile phase, and occasionally we also use water and butylene oxide.
We normally will add some weak acid or weak base into the aqueous phase to turn the whole system into acidic or alkaline. This will make sure that the component can reach the peak. The weak acid or weak base we normally use is methanoic acids, trifluoroacetic acid, ammonium hydroxide, ammonium hydrogen carbonate, etc. The percentage is always the same as the liquid system.
The Load of Reversed-Phase Samples
Commonly we use liquid-phase for wet loading of reversed-phase samples. The solvent we normally use is water, methyl alcohol, butylene oxide, methyl cyanide, NN- dimethylformamide, dimethyl sulfoxide, etc. It is better to choose the most suitable solvent to dissolve, and 100 ml of solvent are best for 100 mg of samples.