6-(6-Aminohexanamido)-hexanoic Acid Methyl Ester Hydrochloride is an intermediate in the synthesis of 6-(6-(6-Aminohexanamido)hexanamido)hexanoic Acid (A618823). 6-(6-(6-Aminohexanamido)hexanamido)hexanoic Acid is used in the making of a preconjugate which serves as immunoreactive conjugate useful as a developer antigen in a competitive inhibition immunoassay for the polymorphic analyte. Also used in the efficient synthesis of a heterobifunctional coupling agent.