Gas chromatographic determination of the temperature limit of alkylpyridine-trisodium phosphate complex formation and its use in identification

Abstract The specific retention volumes, partial molar free energies, enthalpies and entropies of sorption have been determined for eleven pyridine bases on two columns with hydrogenated Apiezon L containing equimolar quantities of trisodium phosphate or potassium fluoride. Thermodynamic characteristics of complex formation between alkylpyridines and trisodium phosphate have been calculated. The determination of the temperature limit for such complex formation by gas chromatography has been elaborated. A method of identification of alkylpyridines in mixtures with hydrocarbons is proposed. The procedure involves comparison of the retention indices of the compounds on the column containing Apiezon L and trisodium phosphate at two analysis temperatures. Alkylpyridines are characterized by sharply decreasing retention indices with increasing temperature.