Hi Andriy,

GPC would be the method of choice. PVP standards are commercially available at PSS Polymer Standards Service. Typical GPC conditions: Run on PSS GRAM columns in DMAC/LiBr.

We can also offer this kind of analysis as sample testing service, if no equipment is available in your Lab.

Best regards

Wolfgang Radke 

Hello Andriy,

I agree with Wolfgang, Gel Permeation Chromatography (GPC), also known as Size Exclusion Chromatography (SEC), would be the best method for determining the molecular weight distribution of your PVP.

There is a recorded webinar on the Malvern website that you may find useful, link below, which discusses the characterization of synthetic polymers and includes a few slides on PVP that describe analysis conditions.

I hope this is of use to you, however if you require further assistance please feel free to contact me directly.

Best Regards,

Stephen.

http://www.malvern.com/en/support/events-and-training/recorded-events/webinar-recorded/RW101026TherapeuticPolymersBiomaterials.aspx

Hi Andriy,

I agree  with Wolfgang choice, the best way to know the molecular weight distribution instead of absolute molecular weight is GPC analysis. If you don´t have the equipment you can buy the sample testing service.

If you have access to another method for  PVP average molecular weight determination (e.g. viscometry, osmometry,etc) you can also try the old fashion way. First to dissolve PVP and them try to have different fractions by selective precipitation with other solvents , then purified each fractions and analyse them one by one...it is somehow a large and tedious procedure involving trial and error tests.

GPC is my best recommendation!!

best regards,

Gustavo

Hi Andriy,

Yes, gel permation chromatography GPC would be a good tool to find the molecular weight distribution. From the distribution you can then obtain the fraction of material above or below any molecular weight, for your case 30,000. As an example of a chromatogram from PVP showing light scattering LS, refractive index RL and viscometry data, please take a look at the attached link to a blog entry.

Best regards, Ulf

http://www.materials-talks.com/blog/2014/01/09/the-chromatogram-series-polyvinylpyridine-pvp/

 U do Mn/Mw ratio

Hi Andriy,

Yes GPC is the best choice as the others mention.

You could also try capillary viscometry. But you'll need to buy a capilalry viscometer and the process is quite tedious.

Otherwise I would recommend a light scattering based approach, if you have access to Zetasizer (Malvern Instruments) it can do the job for you.

 Sir You do the Viscosity method it is Accurate method to determine the Molecular weight of the any  polymers.

Thank you very much, dear all who answered to my question.

Information provided by you helped me to choose the best method. Between these methods I think the most convenient is a light scattering based approach, because of its simplicity and absence of necessity in reference standard samples.

Dear Mr. Damian Kirchmajer, how do you think, Shimadzu SALD-7101 is suitable instrument to perform that analysis?

I've never used this instrument but it looks like it should do the job for you.

Dear all,

what is not said along with the answers of these respectful scientists, is that for a polydisperse polymer, each technique has its own definition and position in the Gaussian distribution of the MW, this means that for the same polymer sample the MW (average) obtained by viscometry will be different from the one obtained by light scattering, and so on. The light scattering though its simplicity, it is a very sensitive technique to additional material present in the sample and stress history, in addition to the processing of the data (Zimm plot).

The other situation in which the polymer is more or less mono-disperse (e.g., polymer synthesis via a living/controlled polymerization technique), here the different values of MW (with respect to the method of getting them) will converge to almost a very close value. Regards

Since Andriy already closed the discussion, I just want to leave with a final comment.

If I get it correctly Andriy does not need the molar mass, but only a fraction of the total molar mass distribution.

Surely each of the above methods (LS, Viscometry) will provide a different MW average. However, methods providing averages only will not solve the Andriys problem. For his question a method suitable to provide the molar mass distribution is required. SEC/GPC is certainly one method. (dynamic) Light scattering (Zeta sizer) can also provide a distribution. I am not an expert for DLS. However, to my knowledge DLS provides a particles size distribution, not a molar mass distribution. Therefore a transformation of the size distribution into a molar mass distribution would be required. As a consequence PVP reference sample(s) is (are) probably still required.

Best regards

Wolfgang