Page 313 - 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)

12 Multidimensional Chromatography:
Industrial and Polymer Applications

Y. V. KAZAKEVICH and R. LOBRUTTO
Seton Hall University, South Orange, NJ, USA

12.1 INTRODUCTION

In this present chapter, applications of multidimensional chromatography to indus-
trial and polymer samples are described, together with general principles and details
of the interfacing setups. The main focus is on complex analyte mixtures or samples
that cannot be analyzed solely by using a single mode of chromatography. Multi-
dimensional chromatography offers the ability to analyze certain components in a
mixture, which is otherwise very difficult, when employing one type of analytical
technique. The advantages of using multidimensional chromatography are increases
in the selectivity and efficiency, plus identification of certain components in a multi-
component mixture.
The use of coupled column technology allows preseparation of complex samples
of industrial chemicals and polymers and on-line transferring of selected fractions
from a primary column to a secondary column for further separation. The resolution
of individual components in a complex matrix and increased peak capacity may be
obtained when using coupled column chromatography. Gas chromatography (GC) is
a very efficient separation technique, but it is not always effective for the resolution
of all components in complex mixtures due to either coelution or a lack of volatility.
The preseparation of the complex sample may be carried out by using liquid chro-
matography (LC), supercritical fluid chromatogaphy (SFC), and even another
GC column of different polarity. The first column may be used to isolate specific
components and fractionate the chemicals by class or group before chromatographic
analysis on the subsequent column. The optimal coupled column chromatography
procedure includes the on-line sample pretreatment and cleanup prior to the final
analytical technique, and results in faster analysis of the components. Coupled sepa-
ration techniques could significantly minimize and often exclude off-line sample
pretreatment and preseparation procedures, which usually include filtration through
prepacked sample tubes, preparative thin layer chromatography, liquid–liquid
partitioning, Soxhlet extraction, and supercritical fluid extraction. These off-line
techniques could result in solute loss, contamination, long workup times and
introduction of human error.