Dear Raghavan These oils are well documented in literature , go into it, study well & then if you dont have  the basic chemical characterization  instruments like NMR , GC.Hplc-MS, IR, UV,  etc etc , in your university, then you can coordinate with any known research group , request them & I am sure many people may help you in that. But sure your problem is not  a tricky one but simple. Dr Abid Aziz Ajaz.

"Fish oil" cannot have a "molecular weight" since it is not a "pure compound". It is usually a mixture of compounds, in which the composition depends heavily on the origin, which fish species it was extracted from, what method was used for the extraction and whether it was blended with other fish oils or other (vegetable) oils. By the same token, the boiling temperature will depend on all the above factors.