28.02.2013 Views

Handbook of Size Exclusion Chromatography and Related ...

Handbook of Size Exclusion Chromatography and Related ...

Handbook of Size Exclusion Chromatography and Related ...

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

Table3 MW<strong>and</strong>MWD<strong>of</strong>aBroad-MWDPAMSt<strong>and</strong>ardShownin<br />

Fig. 2<br />

PAM St<strong>and</strong>ards: PAM 1, PAM 2, PAM 3, PAM 4, PAM 5, <strong>and</strong><br />

PAM 6 (Mw ¼ 3:7 10 4 to 6:0 10 6 g=mole)<br />

M w ¼ 1:1 10 6 g=mole<br />

M n ¼ 5:2 10 4 g=mole<br />

M w=M n ¼ 24<br />

Cumulative wt% Slice MW (g/mole)<br />

0.045 34,409,572<br />

0.432 16,696,033<br />

1.622 8,682,435<br />

6.391 2,829,109<br />

12.761 1,140,318<br />

21.184 544,627<br />

38.745 224,933<br />

56.957 106,853<br />

68.643 65,451<br />

74.720 50,499<br />

86.133 28,440<br />

94.563 14,351<br />

97.324 9,653<br />

99.183 6,216<br />

100.000 3,812<br />

Columns: Guard column þ TSK G6000 PW þ G5000 PW þ G3000 PW.<br />

Mobile phase: 0.15 M Na2SO4 þ 1% acetic acid, pH ¼ 3.1, temperature: 358C.<br />

solution in order to calculate M w. The dn/dc measurement should be carried out<br />

under the same temperature (T) <strong>and</strong> same wavelength (l) as the LALLS<br />

experiment <strong>and</strong> at a constant chemical potential (m). The conditions for a<br />

constant chemical potential can be achieved by dialyzing the polymer solution<br />

against the filtered mobile phase until the dn/dc <strong>of</strong> the polymer solution becomes<br />

constant. In addition, the final concentration <strong>of</strong> the polymer solution should be<br />

determined after dialysis. It was found that when a0.1 g/100 mL-high MW<br />

PAM solution was dialyzed against 2000 mL <strong>of</strong> mobile phase with a1000 MW<br />

cut-<strong>of</strong>f dialysis membrane, it took about three to four days to obtain aconstant<br />

dn/dc <strong>and</strong> resulted in a3to 5wt% mass loss. The concentration <strong>of</strong> polymer<br />

solution was decreased from 0.1 g/100 mL to 0.097 g/100 mL to 0.095g/<br />

100 mL. Other parameters that may affect the dn/dc value are the molecular<br />

weight <strong>of</strong> the polymer <strong>and</strong> the temperature <strong>of</strong> the experiment. Research should be<br />

conducted to define the correct conditions for the dn/dc measurement. Also, it<br />

© 2004 by Marcel Dekker, Inc.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!