New unlabelled and radioactive labelled derivatives of butylamino propiophenone, their preparation, immunogens obtained from the unlabelled derivatives and a process for immunogen preparation antisera raised using the immunogens and a method for raising antisera, a radioimunoassay method and a test kit for use in the assay method

New compounds are prepared having a specific formula. Various methods for their preparation are described. The unlabelled compounds in which R1 and R2 contains a free carboxy group can be coupled with an immunogenic carrier to give an immunogen which can be used to raise antisera in host animals e.g. rabbits. This antisera contains antibodies specific to the antidepressant bupropion. This antisera can be used, together with the radioactive labelled compounds in a radioimmunoassay method for determining bupropion in biological fluids as bupropion and the labelled analogue therof compete for binding sites in the antisera. A test kit for use in the radioimmunoassay contains antisera, radioactive labelled compound and optionally bupropion