What is adsorption

As already mentioned in Section 7.4, the silica strucmre is saturated with silanol groups at the ends. These OH groups are statistically distributed over the whole of the surface (Fig. 9.1). 

The silanol groups represent the active sites in the stationary phase (in alumina, the Al + centres are the most prominent, followed by the linking 0 moieties). They form a weak type of bond with any molecule in the vicinity when any of the following interactions are present  

These situations arise when the molecule has one or several atoms with lone electron pairs or a double bond (for 7i-complex interaction), in other words, when it is unsaturated or carries a so-called functional group. On the other hand, alkanes cannot interact, as they are saturated and consist solely of C and H atoms which carry no lone pairs. 

The adsorption strengths and hence k values (elution series) increase in the following order  

Practical High-Performance Liquid Chromatography, Fourth edition Veronika R. Meyer 2004 John Wiley Sons, Ltd ISBN 0-470-09311-3 (Hardback) 0-470-09378-1 (Paperback) 

The silanol groups represent the active sites in the stationary phase (in alumina, the 

These situations arise when the molecule has one or several atoms with lone electron pairs or a double bond (for 7t-complex interaction), in other words, when it is 

A molecule or a functional group acts as a dipole when the electric charge distribution is not homogeneous throughout the whole molecule or group. The dipole is said to be induced when a charge is moved solely 

Practical High-Performance Liquid Chromatography, Fifth edition Veronika R. Meyer 

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