Hold-up time in gas chromatography -: IV.: Improved determination of Kovats' retention indices

Kovats' retention indices of n-alkanes eluted under isothermal conditions, in nine columns (packed and capillary), at temperatures between 60 and 150 degrees C are calculated by three different methods, and the results are compared with their theoretical values. Two of the methods are based on the linearity assumption of the plot of the logarithms of the adjusted retention times versus carbon number. The third one does not accept the linearity assumption. Results show that methods based on the linearity assumption may produce a clear deviation from the true value of the retention index, while the third method tested, considerably improves the accuracy of the results, showing a similar precision than that obtained by the classical procedures. (C) 1998 Elsevier Science B.V.