Thermodynamic significance of boiling point correlations for alkylbenzenesin gas chromatography - Extension of Trouton's rule

A more exact thermodynamic interpretation of the empirical correlations bet ween retention parameters of solutes (i.e. the relative retention times: ta u (s)) and their boiling points (T-B) was established using Trouton-HiIdebr andt-Everett's rule (the extension of Trouton's rule). These empirical corr elations are known for C-6-C-12 alkylbenzenes for low and medium polar stat ionary phases. A statistical analysis has been made to compare the descript ion by the old and newly developed models. The exponential relation suggest ed earlier [Chromatographia, 44 (1997) 179-186] can be extended into a form consisting of two variables T-M, T-B: tau((i)corr.) = AT(M(i)) exp(BTB(i)) where: tau((i)corr.) = (t(R(i)) - t(0) )/t(R(st)), A = (t(0) Phi/t(R(st)) exp(-4 0). T-M(i) = T-B(i)((TB(i)/T-1)), B = 4.0/T, t(0) is the column dead time, Phi is the phase ratio, t(R(st)) is the retention time of the standard compound, R is the gas constant, T is the column temperature, and subscript '(i)' refers to the ith alkylbenzene . High correlation coefficients and small residual error indicate the super iority of the developed equation, Moreover. the residua show normal behavio r, whereas curvature can be seen in the residua for earlier models. Validit y of the approach proposed was confirmed through a comparison of the numeri cal values obtained from our computation (fitted values) with those stemmin g from theory. (C) 1999 Elsevier Science B.V. All rights reserved.