A method of detecting the presence and amount of a nitrate ester of a polyol in an unknown comprises preparing an antigen based on such an ester and using that antigen to raise antibodies for use in a biochemical assay for the nitrate ester. A preferred antigen is pentaerythritol trinitrate bonded to a protein such as thyroglobulin or BSA. Antibodies can be raised against this antigen in rabbits or other normally used laboratory animals, and the antibodies are used in, for example, a competitive inhibition enzyme immunosorbent assay (CIEIA).