Dear Sir,

I think it is advisable to perform in parallel to SEC experiment a fractional successive precipitation technique. Though it is time and solvent consuming, it has an acceptable accuracy besides its simplicity. Regards

I'm puzzled by the "or I have" implications. How are you determining the Mw and Mn etc. of your collected fractions -- by general (colligative) properties [traditional but roundabout, and requires standards besides!], or by an absolute technique (e.g., low-angle laser light scattering, LALLS) [much better information]?

To check if the separation worked I just used simple SEC measurements (with standards). For the final analysis I use a triple detection SEC with MALLS.