title: Analytical techniques for quantifying (15)N/(14)N of nitrate, nitrite, total dissolved nitrogen and ammonium in environmental samples using a gas chromatograph equipped with a quadrupole mass spectrometer.
abstract: The measurement of (15)N concentrations in environmental samples requires sophisticated pretreatment devices and expensive isotope-ratio mass spectrometry (IRMS). This report describes the use of a gas chromatograph equipped with a quadrupole-type mass spectrometer (GC/MS) to measure (15)N concentrations of ammonium, nitrate, nitrite, and total dissolved nitrogen (TDN) in distilled water, a 2 M KCl solution and a 0.5 M K(2)SO(4) solution. The system measures nitrous oxide (N(2)O) that is ultimately converted from the target N compound, requiring no special apparatus such as a purge-and-trap pretreatment device. It uses a denitrifier lacking N(2)O reductase, which produces N(2)O from nitrate. Persulfate oxidation was applied to convert TDN to nitrate, while additional pretreatment with ammonia diffusion was required for ammonium prior to the persulfate oxidation. Up to 100 samples can be measured daily using the system. We can generally run (15)N measurements with only 1-10 mL of sample for each chemical species of N, a volume 1/10-1/100 times smaller than the amount necessary for conventional methods. Our method is useful for measuring (15)N with GC/MS, offering greater convenience than IRMS.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1–1–1 Yayoi, Bunkyo-ku, Tokyo 113–8657, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Isobe
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Suwa
authors.forename: Junko
authors.initials: J
authors.lastname: Ikutani
authors.forename: Megumi
authors.initials: M
authors.lastname: Kuroiwa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Makita
authors.forename: Yu
authors.initials: Y
authors.lastname: Takebayashi
authors.forename: Muneoki
authors.initials: M
authors.lastname: Yoh
authors.forename: Shigeto
authors.initials: S
authors.lastname: Otsuka
authors.forename: Keishi
authors.initials: K
authors.lastname: Senoo
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ohmori
authors.forename: Keisuke
authors.initials: K
authors.lastname: Koba
mesh_terms: D002849:Chromatography, Gas / Q000379:methods*; D005618:Fresh Water / Q000032:analysis*; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D009566:Nitrates / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis*; D009587:Nitrogen Isotopes / Q000032:analysis*; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D012987:Soil / Q000032:analysis*
chemical_list: D009566:Nitrates; D009573:Nitrites; D009587:Nitrogen Isotopes; D000644:Quaternary Ammonium Compounds; D012987:Soil; D009584:Nitrogen