Ginzburg et al. [106] demonstrated that both axes of the contour plot may be
calibrated for the HT-2D-LC separation of EVA copolymers. PE standards were
used to calibrate the SEC separation, while EVA copolymers with known VA
content were utilized for calibration of HPLC. Moreover, the utilization of TCB
as mobile phase in coupling of HPLC to SEC enables the application of RI, IR,
Visco or LS detectors as was demonstrated by Lee et al. for the 2D-LC separation of
EP and EO copolymers [109]. The calculation of molar masses of polymers eluting
from the 2D-LC system was carried out on the basis of signals from the IR and LS
detectors.
The different separation principles of 2D-LC and TREF-SEC resulted in dissimilar contour plots as obtained from both types of hyphenations. The separation in
Fig. 3.39 Contour diagram of the HT-2D-LC separation of (a) a blend of PE, poly-1-hexene and
an ethylene-1-hexene copolymer and (b) a blend of PE and PPs with different tacticities; stationary
phase: Hypercarb (first dimension) and PL Rapide H (second dimension); mobile phase: gradient
1-decanol/TCB (first dimension) and TCB (second dimension); temperature: 160
C; detector:
ELSD (reprinted from [107] with permission of Elsevier Limited)
3.4 Two-Dimensional Liquid Chromatography
121