2.3.4. Saturation Solubility of FTS in Resin Formulations

The saturation solubility of FTS was determined in all resin formulations used to print rings. For each resin formulation, 100 mg of drug was weighed into individual vials, and 200 mg of resin was added and allowed to stir at RT overnight to dissolve the drug. The mixture was then centrifuged for 15 min at 14,000 rpm (Eppendorf Centrifuge 5417C, Marshall Scientific, Hampton, NH, USA) to remove undissolved drug. Sample aliquots (1–2 mg, *n* = 4) were collected from the saturated supernatant and diluted with acetonitrile (ACN). Drug concentration in the saturated aliquots was determined by HPLC analysis.
