Patent ID: 8318503

Claim:
A method for determining the amount of conjugated taxane in a polyglutamic acid-taxane conjugate wherein one or more taxane molecules are linked through the 2′-hydroxy position to the γ-carboxy group of α-poly-L-glutamic acid said method comprising the steps of: a) reacting the polyglutamic acid-taxane conjugate with a compound of formula (I): R 1 R 2 N—NH 2 (I) wherein R 1 and R 2 are independently C 1 -C 10 -alkyl, C 1 -C 10 -hydroxyalkyl, C 3 -C 10 -alkenyl, C 3 -C 10 -hydroxyalkyl, C 3 -C 10 -alkynyl, C 3 -C 10 -hydroxyalkynyl, aryl, heteroaryl; or R 1 and R 2 taken together with the nitrogen atom to which they are linked form a 3-8 membered heterocyclic ring optionally containing up to three heteroatoms selected from O, S and N and optionally substituted with up to two hydroxy groups; to give an unbound taxane and a polyglutamic acid hydrazide; and (b) determining the amount of unbound taxane.