The measurement of melatonin in mammalian tissues and body fluids.

A quantitative bioassay for melatonin and a radioimmunoassay for melatonin are described and evaluated in terms of their specificity, sensitivity, and practicability. A thin-layer chromatographic method is presented whereby the specificity of the radioimmunoassay for melatonin in blood and tissue extract is affirmed and its specificity in the assay of urinary melatonin is described. Preliminary observations on the relationship between the rate of melatonin excretion and blood levels of melatonin are also reported.