title: In vivo microdialysis/liquid chromatography/tandem mass spectrometry for the on-line monitoring of melatonin in rat.
abstract: Liquid chromatography/tandem mass spectrometry (LC/MS/MS) has been coupled to in vivo microdialysis for on-line monitoring of melatonin in a freely moving rat for a period of 15 hours. A microdialysis probe was surgically implanted into the jugular vein of the rat, and deionized water was used as the perfusion medium at a flow rate of 1.0 microL/min. Microdialysis samples were collected in an on-line injector with sample injection every 30 minutes. Melatonin was dosed by intraperitoneal (i.p.) injection and then monitored by microdialysis/LC/MS/MS. The whole experiment, including the microdialysis sampling and sample injection into the LC/MS system, was fully automated. Metabolites of melatonin were identified off-line by LC/MSn experiments. Two metabolites were identified as 6-hydroxymelatonin and cyclic 2-hydroxymelatonin, consistent with ones found previously in the literature.
authors: Bioanalytical Systems, Inc., West Lafayette, IN 47906, USA.
authors: P S
authors: PS
authors: Wong
authors: K
authors: K
authors: Yoshioka
authors: F
authors: F
authors: Xie
authors: P T
authors: PT
authors: Kissinger
mesh_terms: D000818:Animals; D001711:Biotransformation; D002138:Calibration; D002853:Chromatography, Liquid; D007274:Injections, Intraperitoneal; D008297:Male; D013058:Mass Spectrometry; D008550:Melatonin / Q000031:analogs & derivatives / Q000032:analysis* / Q000493:pharmacokinetics; D017551:Microdialysis; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C052611:1-acetyl-1,2,3,3a,8,8a-hexahydro-8a-hydroxy-5-methoxypyrrolo(2,3-b)indole; D008550:Melatonin; C012365:6-hydroxymelatonin