Page 151 - Multidimensional Chromatography

Coupled Supercritical Fluid and Chromatographic Techniques 143

Figure 6.7 Schematic diagram of an on-line SFE–SFC system (from ref. 42):1, carbon
dioxide; 2, pump; 3, oven; 4, extraction cell; 5, interface; 6, SFC unit.

observed with UV detection, attributed to the solubility of the CO 2 in the aqueous
mobile phase, particularly at low flow rates (28).

6.7 ON-LINE COUPLING OF SUPERCRITICAL FLUID
EXTRACTION WITH CAPILLARY ELECTRODRIVEN
SEPARATION TECHNIQUES (SFE–CESTs)

Electrodriven Separation Techniques encompass a wide range of analytical proce-
dures based on several distinct physical and chemical principles, usually acting
together to perform the required separation. Example of electrophoretic-based tech-
niques includes capillary zone electrophoresis (CZE), capillary isotachophoresis
(CITP), and capillary gel electrophoresis (CGE) (45–47). Some other electrodriven
separation techniques are based not only on electrophoretic principles but rather
on chromatographic principles as well. Examples of the latter are micellar

Figure 6.8 Schematic diagram of a typical interface used for on-line SFE–SFC coupling
(from ref. 42):1, pump; 2, heated transfer line; 3, valve; 4, sample concentrator; 5, valve; 6,
SFC unit.