© 2022. Turk Hijyen ve Deneysel Biyoloji Dergisi. All Rights Reserved.Objective: The aim of this study was to find the efficient medium to bind an anticancer drug, Doxorubicin (DOX), to a synthesized polymer, methoxy poly(ethylene glycol)-block-polycaprolactone (mPEG-b-PCL) via pH sensitive hydrazone bonds and to determine the amount of conjugated drug. Methods: DOX conjugation was carried out in two different media [dimethyl sulfoxide (DMSO) and methanol-trifluoroacetic acid (MeOH-TFA)]. The amount of conjugated drug was determined with two different methods. One method was applied the dissolution of the conjugate in chloroform: methanol (Ch: MeOH, 1: 1 v/v) solution without considering pH responsiveness, and the other method was after breaking pH sensitive hydrazone bonds in acidic medium [using three different media as 0.1 M hydrochloric acid (HCl), concentrated HCl (12 M HCl) and concentrated sulfuric acid (18.3 M H2SO4)]. Results: The highest conjugation efficiency was obtained when the conjugation was achieved in MeOHTFA solution, and for the polymer-drug conjugates after the treatment with concentrated sulfuric acid. Conclusion: It was concluded that, MeOH-TFA method was a good method for conjugation of DOX to mPEG-b-PCL copolymer, and H2SO4 (18.3 M) method was better than any other present in literature for determination of the amount of DOX linked to the polymer via hydrazone conjugation.