The retention behavior of several semisynthetic cephalosporins in planar chromatography

The chromatographic behavior of cephalexine, cefaclore, ceftriaxone, cefiui me, and cefotaxime has been investigated on silica gel layers with binary m obile phases containing different amounts of organic modifier. The influenc e of type, chemical character, and position of substitution of functional g roups (steric and structural effects) on the retention of analyzed compound s was of particular interest. Systematic investigation of the cephalosporins furnished much information a bout their hydrophobicity (R-M(0)), the mechanism of adsorption, and the po ssibilities of separation. Correlation of the hydrophobicity parameters R-M (0), m, and C-0 with the lipophilicity parameter log P was established by u se of linear equations. The parameter C-0 was considered as directly applicable in quantitative str ucture-activity relationships of the cephalosporins.