SEPARATION OF BENZODIOXINIC ISOMERS IN LC - A MOLECULAR MODELING APPROACH FOR THE CHOICE OF THE STATIONARY-PHASE

Seven couples of position isomers on the aromatic ring of benzodioxini c compounds had to be separated. The tries made on classical systems i n gas chromatography or liquid chromatography did not allow the separa tion. We have studied the structures of solutes by molecular modeling. Many molecular descriptors (lipophilic, electronic and steric) were c alculated. Our objective was to compare the relative difference betwee n the isomers in term of lipophilicity, electronic and steric properti es and design the chromatographic system where these interactions are dominant. From these results, the porous graphitic carbon stationary p hase was chosen and allowed a good separation of all the products.