Improved radioimmunoassay of melatonin in serum.

Abstract

Melatonin was extracted from serum by using Baker reversed-phase C-18 columns. More than 99% of the applied melatonin was retained by the columns, and more than 97% was eluted from the columns in 300 microL of methanol. We then determined melatonin in the serum extract by a modification of a standard radioimmunoassay, using filtration instead of centrifugation to collect the [3H]melatonin-antibody complex precipitated by saturated ammonium sulfate. These modifications allow more rapid, accurate, and reproducible determination of melatonin than do previously published procedures.

Measuring melatonin via fast-scan cyclic voltammetry: differentiation of melatonin and by-product matrices to enable long term recording

“…Therefore, methods using systemic sampling cannot distinguish between tissue secretion sites, such as the salivary glands and pineal gland. Tissue speci city can be achieved by extracting samples from speci c tissues and then quantifying melatonin content with ELISA, radioimmunoassay (RIA), or electrochemical detection [26][27][28][29][30][31][32][33][34].…”

Measurement of melatonin in body fluids: Standards, protocols and procedures

“…Briefly, 2 ml of serum sample is passed through an LC-18 cartridge, which is then washed with 2 ml of water and 2 ml of water–methanol (90:10, v/v). Thereafter, melatonin can be eluted from the column with pure methanol, dried and resuspended in an appropriate solution for analysis [ 68 ] or can be further purified by eluting with 2 ml of water–methanol (40:60, v/v) and loading onto a Carbograph cartridge [ 31 ]. The cartridge is then washed with 10 ml of methanol and 3 ml of methanol–dichloromethane (80:20, v/v), and melatonin is finally eluted with 1.5 ml of methanol–dichloromethane (10:90, v/v).…”

“…Sieghart et al [ 68 ] reported that prior melatonin purification from plasma using reversed-phase column chromatography greatly reduces the problems of cross-reactivity. Moreover, Rolčik et al [ 74 ] used immunoaffinity chromatography employing specific antisera to process samples prior to HPLC-MS analysis.…”