Shodex OHpak columns

Record: 752

Category: Specifications
Product: GPC
Sample:

Question
I have attached some chromatograms of the polymer run at 0-10mg/mL. The peak shape continues to be a little assymetrical. It is possible that there are low MW species in the polymer, as suggested by the presence of some weak shoulders in the chromatograms. It is also possible that there is aggregation of the polymer at the highest concentration, hence the shorter elution time for 10mg/mL vs. 5mg/mL. The last possibility is that there is an interaction between the polymer and the column. As a reminder, the polymer is very similar to the one shown below, described in this paper: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3071020/pdf/nihms-280315.pdf

I have tried preparing CHCl3 (our selected mobile phase) with 0.5M Acetic acid and 0.2M NaNO3. The NaNO3 is not soluble in CHCl3. Today I was able to dissolve LiBr at 50mM in CHCl3/0.5M acetic acid. Do you think this would be worth trying? Or perhaps TEA in CHCl3? I thought I would ask before going to the trouble of switching out the mobile phase and purging the entire system.

Answer
As you have experienced, it is difficult to dissolve inorganic salt in CHCl3, so we cannot really recommend the use.
The maximum acetic acid we guaranteed to use is up to 50 mM, so 0.5 M acetic acid is also not recommended.. As well as LiBr which most likely precipitate in CHCl3..

Closest we could recommend would be the condition (b) used below.
This compound could not be analyzed in DMF but was able to do so in condition (b).
http://shodex.net/index.php?seitenid=1&applic=1034
If this compound has similar trend as yours, condition (c) might be worth trying also.

If 100% CHCl3 has to be used, what we can recommend is to add either acid or organic amines (<50 mM & cannot mix both). We are sorry that we cannot suggest a definite condition for the 100% CHCl3 case.     Additional Comments

Download or Print PDF