Page 322 - Multidimensional Chromatography

312 Multidimensional Chromatography

Figure 12.7 Chromatograms of a polycarbonate sample: (a) microcolumn SEC trace; (b)
capillary GC trace of introduced fractions. SEC conditions: fused-silica (30 cm 250 mm
i.d.) packed with PL-GEL (50 Å pore size, 5 mm particle diameter); eluent, THF at a Flow rate
of 2.0ml min; injection size, 200 NL; UV detection at 254 nm; ‘x’ represents the polymer
additive fraction transferred to LC system (ca. 6 L). GC conditions: DB-1 column (15m
0.25 mm i.d., 0.25 m film thickness); deactivated fused-silica uncoated inlet (5 m 0.32
mm i.d.); temperature program, 100 °C for 8 min, rising to 350 °C at a rate of 12°C/min; flame
ionization detection. Peak identification is as follows: 1, 2,4-tert-butylphenol; 2, nonylphenol
isomers; 3, di(4-tert-butylphenyl) carbonate; 4, Tinuvin 329; 5, solvent impurity; 6, Irgaphos
168 (oxidized). Reprinted with permission from Ref. (14).

pyrolysis gas chromatography for characterization of a styrene–acrylonitrile
copolymer. This system used a 10-port valve and a glass chamber interface for the
analysis of non-volatile compounds. A more complete description of the microcol-
umn liquid chromatography–pyrolysis gas chromatography interface is given in the
original reference (15). It is advantageous to use a coupled mode since fractions do
not have to be collected manually, evaporated, redissolved in a certain solvent and
then manually transferred to a pyrolysis probe by using a syringe. For the characteri-
zation of polymers, the coupled techniques of SEC and pyrolysis GC allow the deter-
mination of average polymer composition as a function of molecular size. This may
also elucidate a more comprehensive understanding of the polymer properties and
the polymerization chemistry of particular systems.