[{"from": "human", "value": "Use the given information to create a molecule that fulfills the desired purpose. The molecule is a monoalkyl phosphate epitope having ethyl as the alkyl group. It has a role as an epitope and a phosphoantigen. It is a conjugate acid of an ethyl hydrogen phosphate(1-)."}, {"from": "gpt", "value": "[C][C][O][P][=Branch1][C][=O][Branch1][C][O][O]"}]