Estimation of normal boiling points of trialkyl phosphates using retention indices by gas chromatography

Retention indices of several homologous trialkyl phosphates have been determined by gas chromatography on different polar stationary phases namely, Apiezon L, SE-30 and XE-60. Normal boiling points of these trialkyl phosphates have been evaluated and compared with available literature values. Topological indices such as Xu index, atom type index and steric effect index are derived for these phosphates and have been correlated with the normal boiling points using multiple regression analysis. The influences of alkyl chain length, relative position of alkyl branching and steric factors on retention index are investigated and also the effect of polarity of the stationary phase on retention indices is discussed.