Abstract: The present invention is concerned with novel derivatives of cyanocobalamin (vitamin B.sub.12), especially of the monocarboxylic acid hydrolysates thereof, by which (1) an antigenic conjugate thereof with a protein is obtainable and (2) a readily iodinatable aromatic ring can be introduced while retaining in each instance, the essential constitution of cyanocobalamin to such an extent that (a) the antigenic protein conjugate, when introduced into the blood stream of a vertebrate, causes the formation of an antibody which is specific to the cyanocobalamin portion of the conjugate and (b) unmodified cyanocobalamin and the second-mentioned derivative when tagged or labeled with radioactive-iodine competitively bind on the aforementioned antibody. Thus, the present invention provides cyanocobalamin derivatives which are quite useful in radioimmunoassay (RIA) of vitamin B.sub.12.

Abstract: The present invention is concerned with the radioimmunoassay (RIA) procedure for assaying body fluid content of an antigenic substance which may either be an antigen itself or a hapten capable of being converted, such as by means of reaction with a protein, to an antigenic material. The present invention is concerned with a novel and improved modification of a double-antibody RIA technique in which there is a first antibody that is specific to the antigenic substance suspected to be present in a body fluid from which the assay is intended. The second antibody, however, is not specific to the antigenic substance or analyte, but is an antibody against the first antibody.

Abstract: The present invention is concerned with the production of novel derivatives of thyroid hormones which are useful in the radioimmunoassay (RIA) of such hormones. The invention is particularly concerned with derivatives of thyroxine and triiodothyronine which contain an additional phenol group which is readily iodinatable so that the phenol conjugate can be readily tagged with a radioactive iodine isotope, such as .sup.125 I or .sup.131 I, without detrimentally interfering with the ability of the tagged conjugate so competitively bind with the naturally occurring thyroid hormone in the biological liquid to be analyzed by RIA technique. The invention is also concerned with the iodine-tagged derivatives or conjugates.

Abstract: The present invention is concerned with novel derivatives of cyanocobalamin (vitamin B.sub.12), especially of the monocarboxylic acid hydrolysates thereof, by which (1) an antigenic conjugate thereof with a protein is obtainable and (2) a readily iodinatable aromatic ring can be introduced while retaining in each instance, the essential constitution of cyanocobalamin to such an extent that (a) the antigenic protein conjugate, when introduced into the blood stream of a vertebrate, causes the formation of an antibody which is specific to the cyanocobalamin portion of the conjugate and (b) unmodified cyanocobalamin and the second-mentioned derivative when tagged or labeled with radioactive-iodine competitively bind on the aforementioned antibody. Thus, the present invention provides cyanocobalamin derivatives which are quite useful in radioimmunoassay (RIA) of vitamin B.sub.12.