Analysis of petroleum fractions by on‐line micro HPLC‐HRGC coupling, involving increased efficiency in using retention gaps by partially concurrent solvent evaporation

Abstract

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.

Solvent Trapping during Large Volume Injection with an Early Vapor Exit. Part 3: The Main Cause of Volatile Component Loss during Partially Concurrent Evaporation

“…And what do the losses depend on? No losses were observed when partially concurrent evaporation was introduced in 1985 -albeit without a solvent vapor exit [6].…”

Solvent Trapping during Large Volume Injection with an Early Vapor Exit, Part 1: Description of the Flooding Process

“…For volumes exceeding about 150 ll, this called for inconveniently large precolumns. Partially concurrent evaporation is preferable [27,28]. The injection rate is reduced near to the evaporation rate such that a substantial proportion of the sample solvent is volatilized during its introduction and merely a small proportion of the sample needs to be retained as a liquid at the end of the injection or transfer.…”

Microcolumn liquid chromatography: instrumentation, detection and applications

“…multidimensional chromatography. Microcolumn LC has been interfaced with thin-layer chromatography applying infrared detection [220], conventional high-performance liquid chromatography [2211, microcolumn LC [222][223][224], gas chromatography [225][226][227][228][229][230][231], supercritical fluid chromatography [232] and capillary electrophoresis [233]. The coupling of individual separation techniques increases the total peak capacity of the chromatographic system, which is equal to the product of the peak capacities of the individual dimensions.…”