Influencing Factor of Reversed-Phase Chromatography
In reversed-phase chromatography, the stationary phase is a non-polar bonded phase, such as octadecylsilane (C18, ODS), octyl (C8) bonded silica; mobile phase water as the base solvent, adding a certain amount of water mixed Dissolved polar regulator
A weakly polar bonded phase, a bonded phase such as an ether group and a dihydroxy group, used for reversed phase or normal phase chromatography.
1. Molecular structure of solute (polarity)
The weaker the polarity, the stronger the hydrophobicity, and the larger k, the larger the tR.
The more the carbon number of the homolog, the weaker the polarity, and the larger the k;
The introduction of a polar substituent reduces the hydrophobicity and the k value becomes smaller.
2. stationary phase
The hydrophobicity of the bonded alkyl group increases as the carbon chain is extended, and the k of the solute also increases.
The greater the concentration of the alkyl group bonded to the surface of the silica gel, the larger the k of the solute.
3. Mobile phase
The stronger the polarity, the weaker the elution ability, and the larger the k of the solute
Solvent type: water is a weak solvent, alcohol is a strong solvent
Solvent ratio: the proportion of water increases, causing k to increase
Addition of salt: increase the k of the neutral solute