Comparison of Retention Indices of Some Monosubstituted Benzenes Calculated by Different Mathematical Methods in RP-LC

In reversed phase liquid chromatography, the retention indices of benzene and nine mono substituted benzenes with different functionality based on the alkan-2-ones and alkyl aryl ketones retention index standards have been determined by the application of two new mathematical adaptation methods, viz. a multiparametric least-squares regression iterative method based on the determination of the adjusted retention times and a local cubic interpolation method directly using the total retention times. The two methods were applied to two types of columns. The first group includes four octadecyl-C(18) columns with different packing materials obtained from different manufacturers, while the second comprises an octyl-C(8) column. The retention indices have been extensively studied using either methanol-water or acetonitrile-water mobile phase systems. The influences of the concentration of the organic modifier in the mobile phase (methanol or acetonitrile), the column temperature, and the column packing material on retention indices of the set of the ten monoaromatics studied were also investigated. The calculated multiparametric retention indices values, those obtained by the local cubic interpolation and Kovats' methods are compared. Good agreement was observed between the retention indices calculated by the three methods.