Two-dimensional chromatography of gasoline by on-line coupled HPLC-HRGC, as described in this paper, allows separarate GC analysis of paraffins and aromatics. The GC system contains a retention gap of only 10 rn length for introducing HPLC fractions of 100 pl volume. This becomes possible through evaporation of part of the solvent during introduction of the HPLC eluent. This "partially concurrent solvent evaporation" technique allows transfer of large volumes of HPLC eluent into relatively short retention gaps, maintaining the full efficiency of the solvent effects in reconcentrating the bands of the early eluted solutes.

New results obtained with microbore or microcapillary columns packed with DACH-DNB CSP (spherical silica, 5 pm) using conventional LC eluents or supercritical fluids are reported. Examples of direct chromatographic separations of complex mixtures of stereoisomers on: a) long, packed microbore or microcapillary columns and b) several columns coupled in series are shown; in the latter case, a home-made calculation procedure (Simulation for Multi-Column Chromatography -SMCC) was used to quickly select the optimal conditions (kind of stationary phases and relative columns length).

Adsorptive enrichmenthhermal desorption Micro t r a p VOC and PVOC analysis Humid air sample analysis. SummaryAn instrument has been developed and tested for the continuous measurement of volatile organic compounds (VOC) in air. The system consists of a gas chromatograph equipped with a dedicated sampling device that allows the sample to be transferred to a cooled microtrap via sampling loops (10,100,250 ml) or via a direct pump transfer to the trap. The microtrap is placed in the chromatographic oven just below a modified split-splitless injector, allowing direct liquid injection for calibration of the system; the injector is in communication with the sampling valve equipped with the loop and the sampling pump. The system allows 24-hour sampling and analysis of a large number of VOC (up to 25 individual hydrocarbons ranging from C2-C9) and also polar volatile organic compounds PVOC. Thanks to the particular trap geometry, a minimum consumption of liquid nitrogen (between 150-300 ml) is needed for each analytical run and no water managing system is normally required for humid air samples.

SummaryFast and efficient separations of chiral stereolabile compounds were obtained at very low temperature on a n-acid chiral stationary phase (R,R-DACH-DNB) using carbon dioxide-based mobile phases containing alcoholic polar modifiers.Furthermore, efficient separations of the newly discovered spherical carbon cluster buckminsterfullerene (c60) and the related higher fullerenes (C70, etc.) have been performed on the same stationary phase using eluents based on either n-hexane or carbon dioxide.