Page 344 - 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)

13 Multidimensional Chromatography
in Environmental Analysis

R. M. MARCÉ
Universitat Rovira i Virgili, Tarragona, Spain

13.1 INTRODUCTION

Multidimensional chromatography has important applications in environmental
analysis. Environmental samples may be very complex, and the fact that the range of
polarity of the components is very wide, and that there are a good many isomers or
congeners with similar or identical retention characteristics, does not allow their
separation by using just one chromatographic method.
The main aims in environmental analysis are sensitivity (due to the low concen-
tration of microcontaminants to be determined), selectivity (due to the complexity of
the sample) and automation of analysis (to increase the throughput in control analy-
sis). These three aims are achieved by multidimensional chromatography: sensitivity
is enhanced by large-volume injection techniques combined with peak compression,
selectivity is obviously enhanced if one uses two separations with different selectivi-
ties instead of one, while on-line techniques reduce the number of manual operations
in the analytical procedure.
For analytical purposes, environmental analysis can be divided into the control of
pollution and the analysis of target compounds. For the control of pollution, it is
important to monitor both well-known priority pollutants and all of the other non-
priority pollutants. The selectivity of the analytical column may therefore not be suf-
ficient. In most cases, however, mass spectrometry (MS) detection can solve the
problem and this is why gas chromatography GC–MS is widely used in routine anal-
ysis. Sometimes, however, MS, and even MS/MS (which requires complex instru-
mentation) may not solve the problem and multidimensional chromatography is then
a suitable technique. The low levels at which the micropollutants are to be deter-
mined is another drawback and multidimensional techniques are a good solution to
this problem. In pollution control, high throughput is required and this may be
obtained by automating the analysis via multidimensional chromatography, which
also reduces the possible sources of error.
In target-compound analysis, a particular compound, usually present in a
complex matrix and at trace levels, needs to be quantified. Here, selectivity and