Analysis of melatonin in human plasma by gas chromatography negative chemical ionization mass spectrometry

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Science  25 Aug 1978:
Vol. 201, Issue 4357, pp. 741-743
DOI: 10.1126/science.675255


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.