Will lead bind to dissolved polymer (Kapton) monomers?

We are attempting to determine the concentration of lead impurities in Kapton. Essentially we need to extract lead in the tape polymer Kapton (structure seen below);


[![Chemical stucture of Kapton](https://i.stack.imgur.com/wX1ok.png)](https://i.stack.imgur.com/wX1ok.png)


The amount of lead in the tape is expected to be extremely low. I plan on dissolving the Kapton into its monomers using a mixture of NaOH and hydrazine(N2H4). The process of then extracting lead ions from solution is figured out. However, I have to be sure that approximately 100% of the lead which is in the Kapton is dissolved in solution and not bonded to the Kapton monomers. 


Will the oxygens on the monomers bond with any lead ions and therefore inhibiting any further reaction with that lead atom? If so is there a way to separate the lead atoms from the Kapton monomers?


Since we actually add lead separately as we are looking at the isotopic ratio, another solution to this issue would be if the lead binds to the Kapton only rapidly and is then replaced with another lead atom. This would mean that the ratio of added lead and lead impurity are equal in the solution as well and in the Kapton monomers. Is this a valid assumption over a certain time period?


Any comments would be helpful. Thank you.


