title: Analysis of melatonin in human plasma by gas chromatography negative chemical ionization mass spectrometry.
abstract: Three techniques have been used to measure human plasma melatonin: bioassay, radioimmunoassay, and gas chromatography--mass spectrometry (GC-MS). GC-MS is theoretically capable of the greatest specificity, but in general suffers from insufficient sensitivity. Negative chemical ionization, a new technique, provides a 150-fold increase in GC-MS sensitivity for electron-capturing compounds. Negative chemical ionization GC-MS permits routine measurement in human plasma of melatonin at a concentration as low as 1 picogram per milliliter.
mesh_terms: D000328:Adult; D000838:Anions; D002849:Chromatography, Gas / Q000379:methods; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008550:Melatonin / Q000097:blood*
chemical_list: D000838:Anions; D008550:Melatonin