conjugation of methotrexate (mtx) (mw 454) with different molecular weights of polyethylene glycol (peg) including methoxy-peg (mpeg) 750 d and 5000 d and diol-peg 35000 d led to compounds that are physicochemically highly different from the parent compound, mtx. in this study, an hplc system consisting of c8 column and uv detector (?=342 nm), using a mixture of 30:70 v/v phosphate-citrate buff...
