I'm not a chemist, but skimming the paper it certainly sounds like the cellulose itself is what they are measuring: > Following, ATR-FTIR analysis was performe

I'm not a chemist, but skimming the paper it certainly sounds like the cellulose itself is what they are measuring: > Following, ATR-FTIR analysis was performed in the teabags as well as in the leached mixture of nanoparticles plus fibers (Fig. 3). Both teabags and the leachate suspension matched their polymer composition being two of them petroleum-based polymers like nylon-6 (NY6, sample 1) and polypropylene (PP, sample 2), the third one (from the supermarket) being cellulose (CL, sample 3), a bio-based polymer. I didn't see any mention of plastic binders or other material in the cellulose sample, just references to cellulose. On the other hand, it was curious that they purchased the synthetic bags empty, but cellulose bags filled with tea, when it is pretty easy to find empty paper tea bags, so maybe there is something particular about the specific type of cellulose tea bag they chose?