Immobilized Cellulose and Amylose Derivatives

The option to use the non-standard solvents in the mobile phase opens up new possibilities for unique selectivities. There are also no limitations on the sample injection solvent with the immobilized phases. Solvents such as dichloro-methane, acetone, THF, dimethylformamide (DMF) or even dimethyl sulfoxide (DMSO) can be safely and effectively used as sample diluents. This is highly beneficial for the automation of injections for samples coming directly from various synthetic media, e.g. from lab-automation experiments. On the other side the immobilisation changes the selectivity of the stationary phase and compounds not resolved on the coated CSPs can be resolved by the immobilized CSP. 

In order to modify retention times and to improve peak shapes the proportion of alkane can be increased or decreased. In many cases it is useful to add a small amount of alcohol to enhance selectivity and/or reduce retention times and/or improve the method. Addition of alcohols to certain mixtures, such as alkane/ dichloromethane will strongly modify separations. In the case of TBME (last column in Table 5) EtOH can be substitued by another alcohol or THF. 

Croup A Alkane Alkane Alkane Alkane Alkane Alkane Ethanol 

Croup B CHClj EtOAc THF CH2CI2 toluene acetone TBME 

Using the following four solvent mixtures a straightforward approach for the screening of these phases can be made  

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