The present invention provides a novel carbamazepine hydrazide compound suitable for covalent attachment to a polymer particle reagent, having the general formula ##STR1## The present invention also provides a novel carbamazepine acid compound suitable for attachment to proteins for the production of carbamazepine immunogens. The carbamazepine antigen of the present invention has the following general structure: ##STR2## where X is C.dbd.O, CH.sub.2 or SO.sub.2 ; Y is C.dbd.O, CH.sub.2, SO.sub.2 ; R is an alkyl and P is a protein or a hapten.
