Separation of strength and selectivity of mobile phase by spectral mapping technique

The retention behaviour of seven monotetrazolium and nine ditetrazolium salts was studied in seven different mobile phases on alumina and impregnated alumina stationary phases. The strength and selectivity of the components of mobile phases were separately calculated by the spectral mapping technique. It was established that tetrahydrofuran (THF) has the highest solvent strength while the differences among ethanol, 1-propanol, 2-propanol and dioxane were relatively low. The selectivity of THF was also considerably different from those of other solvents. Hydrophobicity and electronic parameters were equally involved in the retention strength and selectivity of tetrazolium salts, indicating the mixed character of their interaction with the alumina stationary phase.