GPC results - obtaining Mw, Mn, Mz, Mz+1 and PD

[d.myles]

Hi there,
Did Gel permermeation Chromatography on Polystyrene in a lab session, the results have been given to us as an excel sheet with collumn headings "Retention Time, Reponse, MW, LogMW"

We need to find Mp, Mw, Mn, Mz, Mz+1 and PD. I have figured out that Mp is at the crest of the peak, but i have no clue what to do to find Mn, Mw, Mz and Mz+1.
then PD = Mn / Mw (or the other way around)

Thanks. (btw, report due in 6 hours so not sdure if ill get a response in time)

[d.myles]

ok, i understand a little bit more now.

Mn = (Sum(Mi x ni)) / (Sum(ni))

Mw = (Sum(Mi^2 x ni))/(Sum(ni))

but what do i use for ni? The values in the response collumn?

[bisnettrj2]

Ni is the number of molecules having a particular molecular weight.

Try this link for help:

http://pslc.ws/mactest/average.htm

[d.myles]

Hi,
I understand how ni is number of moleculesrepresenting each mass, but what i dont know is how to get n from the data i have. All i have is the 'response' of each Molecular Weight in millivolts?

[d.myles]

my demonstarator gave me some hints.

In the results, there is another collumn titled "Norm Ht", and he said that this is related to ni.
The relationship/equation is not in my text book, lec notes. Looking round on net but no luck so far