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SummaryThis work deals with the investigation of the possibilities and limitations using a commercially available software package Drylab for the fast optimisation of running conditions and the prediction of separation and retention times of a mixture consisting of fourteen neutral (nitramines, aminonitroaromatics and nitroaromatics) and six acidic (nitrophenols) explosive-related compounds.Especially the influence of some important experimental parameters, as the concentration of organic modifier in mobile phase or aqueous mobile phase pH value on the prediction of retention times was investigated. The portabili b, of these results onto other columns packed with different, but nominally identical octaclecyl-modified silica (C18) packing materials or obtained from different manufacturers, were also discussed.Using the computer simulation program DryLab made it possible to find the best separation conditions quickly e.g.within l",,vo runs for composition and three runs for pH value of the mobile phase and without testing a large number of possible chromatographic conditions. The optimization resulted in resolution Rs > 1.5 forall explosives and related compounds investigated.The correlation bef,,veen the simulated run with the theoretical optimum and the final experiment was satisfactory in spite of changes of methanol concentration in the mobile phase or its pH value. Good agreement bef,,veen experimentally obtained and computer-predicted retention times were fou ncl. The average difference do not exceed 5% in most cases.

In reversed phase liquid chromatography (RP‐HPLC), the validity of a multiparametric non‐linear least‐squares regression iterative method for the determination of the column dead time tM and the regression parameter (slope b), based on the use of alkan‐2‐ones, alkyl aryl ketones, and 1‐nitroalkanes has been evaluated. The determination of tM and b has been extensively studied for two mobile phase systems acetonitrile‐water and methanol‐water on seven octadecyl‐C18 and one octyl C8 analytical columns. The calculated tM and b values were compared with those obtained by Guardino's and Grobler's methods. The influence exerted thereon by the nature of the homologous series, the mobile phase composition, and the packing materials were investigated.

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