Chromatography Forum

Hello all,

I am requested to analyse alcoolic extracts of tannins (from oak) and some fruits (berries...) (in a powder form). I must compare and cross informations obtained by 3 methods:

Reverse Phase HPLC
Normal Phase HPLC and
Size Exclusion Chromatography

For RP HPLC and SEC there is no problem (I mean, I see what I can obtain : from the first one information on specific components of interest and from the second one I can obtain a MW profile of the extracts), but :

What kind of information can I obtain from NP-HPLC, which I cannot from the other 2 technics?
Are the interactions not only chemical in NP HPLC? (as I saw (from bibliography) that NP- HPLC is used to separate polymers in a similar way to SEC)

My questions are maybe too simple, but I'm not experienced in this field and I am a little confused...

Thank you in advance

Best regards

Carmen,

NP-HPLC is based on sample/column interactions also except that in NP-HPLC the column is polar and the mobile phase is non-polar with a small percent of polar modifier. Sample interactions are based on the polar interactions between sample and column. NP-HPLC results are therefore, complimentary to RP-HPLC results. NP-HPLC is also used when the sample components are mostly non-polar and soluble in non-polar solvents.

thank you for your answer,

only after having posted my message yesterday I realised that I should have thought twice before...

Now I can see clearer
I have understood that actually, in my compounds polarity is related to size... that's why I had been confused! ... (my mind was not clear enough because of Monday!)

but thankn you anyway!