Handbook of Size Exclusion Chromatography and Related ...

Table 6 Weight-Average Molecular Weight (M w) and Polydispersity (M w=M n) of
Polyacrylamides
Measured M w and M w=M n (relative to PAM standards)
Given M w
by LALLS
Determined from
column set 1
Determined from
column set 2
Sample (g/mole) M w (g/mole) M w=M n M w (g/mole) M w=M n
PAM 1 6.0 10 6
PAM 2 1.3 10 6
PAM 3 5.0 10 5
PAM 4 1.6 10 5
PAM 5 3.7 10 4
(1.8 10 6 g/mole) determined from universal calibration is about one-third of
its relative M w (5.0 10 5 g/mole) determined from PAM standards.
3.3.3 MW and Column Pore Size Distribution
Table 6 shows the M w determined from two column pore size distributions and
two mobile phases. The M w values determined from two systems for four PAM
samples 1, 2, 3, and 5 agree very well. Also, their M w values agree with the given
values. However, for sample 4, the M w (l.6 10 5 g/mole) determined from four
columns (TSK G6000/5000/4000/3000 PWXL) and the neutral pH mobile phase
agrees with the given M w while the M w (2.0 10 5 g/mole) determined from
three columns (TSK G6000/5000/3000 PW) and the acidic pH (3.1) mobile
phase is about 25% higher than the given M w (1.6 10 5 g/mole). It seems that
the pore size of a TSK G4000PWXL column gives a better separation for the MW
range of 1.0 10 4 to 2.0 10 5 g/mole.
4 APPLICATIONS OF SEC
5.85 10 6
1.18 10 6
5.15 10 5
1.64 10 5
3.70 10 4
Column Set 1: TSK G6000/5000/4000/3000/PWXL,
0.3 M NaCl þ 0.1 M KH 2PO 4,pH¼ 7.0;
Column Set 2: TSK G6000/5000/4000 PW,
0.15 M Na2SO4 þ 1% (v/v) acetic acid, pH v 3.1.
3.83 5.78 10 6
3.99 1.16 10 6
2.92 5.23 10 5
1.93 2.02 10 5
2.03 3.66 10 4
3.87
3.95
3.38
2.44
1.93
SEC is mainly used for determining MW and MWD simultaneously. Other
applications of SEC technique for various studies in industry have been reported
in Refs 25, 37, 38, and 40. Additional projects, which have been carried out by the
author, will be discussed in this section.
© 2004 by Marcel Dekker, Inc.