Page 328 - Multidimensional Chromatography

318 Multidimensional Chromatography

Figure 12.11 Coupled SEC–RPLC separation of compound Chemigum rubber stock:
(a) SEC trace; (b) RPLC trace of fraction 1, dibutylphthalate; (c) RPLC trace of fraction
2, elemental sulfur. Coupled SEC conditions: MicroPak TSK 3000H (50 cm) 2000H
(50 cm) 1000 H (80 cm) columns (8 mm i.d.); eluent, THF at a flow rate of 1 mL min; UV
detection at 215 nm (1.0 a.u.f.s.); injection volume, 200 L. RPLC conditions: MicroPak
MCH (25 cm 2.2 mm i.d.) column; flow rate, 0.5 mL/min; injection volume, 10 L; gradi-
ent, acetonitrile–water (20 : 80 v/v) to 100% acetonitrile at 3% acetonitrile/min; UV detec-
tion at 254 nm (0.05 a.u.f.s.). Reprinted from Journal of Chromatography, 149, E. L. Johnson
et al., ‘Coupled column chromatography employing exclusion and a reversed phase. A poten-
tial general approach to sequential analysis’, pp. 571–585, copyright 1978, with permission
from Elsevier Science.

isopropyl ether has been carried out, as well as heart-cutting without trapping of the
selected fractions (19). The reaction mixture was preseparated on a 20 m poly
(propylene glycol) column and then re-injected on a Marlophen column (100 m
0.25 mm i.d.). The separation with trapping demonstrated the effectiveness of the
trapping and re-injection procedure since more of the solvent peak that results from
the fronting of the tail is eliminated and does not interfere by overlapping with peaks
of higher retention on the second column. This allows well resolved chromatograms