摘要 |
There is disclosed a "cold", i.e., non-radioactive (stable) isotope method for the immunoassay of biological compounds. The method uses selenium as the tracer label in compounds which compete in reaction with a conjugating compound and thus yield a solution for analysis which is a mixture of complexes of the conjugating compound with the selenium labelled and unlabelled compound. The nonradioactive isotope can be analyzed using fluorimetric determinations with proper preparatory treatment or atomic adsorption. Selenium is particularly unique in its adaptability to this assay because of its great compatibility with biochemicals, e.g., it has an atomic size and structure and chemical properties very close to that of sulfur and it readily forms compounds and small adducts with carbon and hydrogen containing compounds. Selenium is also ideally suited for use in this assay because it can be quantitatively detected at extremely low concentrations, e.g., the lower detection limit is presently about 10-9 to 10-10 grams per milliliter.
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