Hi Rajen

Your analytic depends on the availybility of your molecules.

Natural polymers mostly don't appear as discrete single molecules from one exact size too, so your mehtods will be more related to problems of traditional polymer analytics.

First question might be: do you have a homogenous solution of your analytical target or is it a mix of dissolved, colloidal or solid particles, like many natural polymers? So you might have to apply different methods to give a final answer.

Usually photometric methods like light scattering are common methods for a description of inhomogeneous mixes. Maybe your target responds to ultra-centrifugation, if it is more colloidal or dissolved maybe to Field-Flux-Fraction (FFF) or Gel Permeation Chromatography (GPC/SEC), maybe you need.

For solid and macrostructures you can think about NMR, ESR, IR or x-Ray spectroscopies  or you perform an enzymatical or chemical digest to identify the consumption of amino acids or other monomeric parts.

For rheological measurements use a viscosimeter. Thermal analysis differential scanning calorimetry. Avaerage-number molecular weight by gel permeation chromatography

Thanks  a lot !