Unknown peak in UV but not DRI

[cms12]

Thanks in advance for any guidance!

SEC analysis on a final product (synthetic resin) shows a perfectly ongrade product via DRI detection; however, UV analysis shows a huge jump in molecular weight due to some unknown species being detected in a higher MW range.

My current thought process is that some HMW contaminent is present that has the same RI as my solvent (THF).

Does this seem to be the correct thought direction? Anyone have any advice? (tables etc of RI perhaps?)

Thanks!!

[tom jupille]

Or, you have a very small amount of a high MW component which has a very intense chromophore at whatever wavelength you are working.

[cms12]

Thank, Tom-- An alll too simple answer that hadn't crossed my mind...should have known.

I'm going to do some further analysis via GC and TGA to try to confirm a low quantify of the unknown HMW species.