APPLICATION OF TOPOGRAPHIC INDEXES TO CHROMATOGRAPHIC DATA - CALCULATION OF THE RETENTION INDEXES OF ALKANES

Gas chromatographic (GC) data on alkanes have been re-examined from a structural point of view with emphasis on the distances in optimum (minimum-energy) conformations. The information on the distances in an alkane G is embodied in the topographic (geometric) distance matrix D(G) and the related 3-D Wiener number 3W(G) of G. The optimum 3-D structures of alkanes were obtained from the molecular mechanics computations. The GC retention indices (I) of 157 alkanes were calculated using a three-parameter equation of the form I = alpha [3W(G)]b + c. The calculated I values are in excellent agreement with the experimental values. A comparison between the reported results and those obtained with the 2-D Wiener number and the connectivity index is also discussed.