Page 387 - Multidimensional Chromatography

Multidimensional Chromatography
Edited by Luigi Mondello, Alastair C. Lewis and Keith D. Bartle
Copyright © 2002 John Wiley & Sons Ltd
ISBNs: 0-471-98869-3 (Hardback); 0-470-84577-5 (Electronic)

14 Multidimensional Chromatographic
Applications in the Oil Industry

J. BEENS
Free University de Boelelaan 1083, Amsterdam, The Netherlands

14.1 INTRODUCTION

From its very beginnings, chromatography has played an important role in the oil
industry, with workers in this field having developed many important fundamentals
of the technique. The names of van Deemter, Keulemans, Rijnders and Sie are still
remembered from those early days of chromatography, where some quite fundamen-
tal work had been performed in an industrial environment. The main reason for this
is the fact that chromatography is an outstanding technique for analysing the com-
plex samples that are present in the oil industry. Csaba Horváth stressed this in his
Golay Award Lecture at the 21st International Symposium on Capillary Chromato-
graphy and Electrophoresis in Salt Lake City in June 1999: ‘The rapid growth of gas
chromatography was fuelled by the exploding need of the petroleum based industries
for suitable tools after the war’.
The complexity of oil fractions is not so much the number of different classes of
compounds, but the total number of components that can be present. Even more
challenging is the fact that, unlike the situation with other complex samples, in
which only a few specific compounds have to be separated from the matrix, in oil
fractions the components of the matrix itself are the analytes. Figure 14.1 presents an
estimation (by extrapolation) of the total number of possible hydrocarbon isomers
with up to twenty carbon atoms present in oil fractions. Although probably not all of
these isomers are always present, these numbers are nevertheless somewhat over-
whelming. This makes a complete compositional analysis using a single column sep-
aration of unsaturated fractions with boiling points above 100 °C utterly impossible.
For this reason, multidimensional gas chromatography (GC) has been introduced
as a means of increasing the separating efficiency. This was already explored in the
late 1950s on chlorinated hydrocarbons with two packed columns and designated as
two-stage chromatography (1, 2). A fully integrated system for the complete analysis
of all of the constituents of a refinery off-gas by using four different columns was
presented in 1961 by Bloch (3). Since then the number and type of multidimensional
systems for the analysis of petroleum fractions has steadily increased, but most of