Analytical Techniques for Quantifying 15N/14N of Nitrate, Nitrite, Total Dissolved Nitrogen and Ammonium in Environmental Samples Using a Gas Chromatograph Equipped with a Quadrupole Mass Spectrometer
Analytical Techniques for Quantifying 15N/14N of Nitrate, Nitrite, Total Dissolved Nitrogen and Ammonium in Environmental Samples Using a Gas Chromatograph Equipped with a Quadrupole Mass Spectrometer
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DOI：
10.1264/jsme2.me10159
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发表时间：
2011-03-05
影响因子：
2.2
通讯作者：
Koba, Keisuke
中科院分区：
文献类型：
--
作者：
Isobe, Kazuo;Suwa, Yuichi;Koba, Keisuke
环境样品中N-15浓度的测量需要复杂的预处理设备和昂贵的同位素比质谱（IRMS）。本报告描述了使用配备四极杆型质谱仪（GC/MS）的气相色谱仪测量蒸馏水、2 M KCl溶液和0.5 M K2 SO 4溶液中铵、硝酸盐、亚硝酸盐和总溶解氮（TDN）的N-15浓度。该系统测量最终从目标N化合物转化的一氧化二氮（N2 O），不需要诸如吹扫和捕集预处理装置的特殊设备。它使用了一种缺乏N2 O还原酶的发酵剂，该还原酶从硝酸盐中产生N2 O。应用过硫酸盐氧化将TDN转化为硝酸盐，而在过硫酸盐氧化之前，铵需要用氨扩散进行额外的预处理。使用该系统每天可测量多达100个样品。我们通常可以运行N-15测量，对于每种N化学物质，仅需1-10 mL样品，体积比传统方法所需的量小1 - 10-1/100。该方法可用于GC/MS测定N-15，比IRMS更方便。
The measurement of N-15 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 N-15 concentrations of ammonium, nitrate, nitrite, and total dissolved nitrogen (TDN) in distilled water, a 2 M KCl solution and a 0.5 M K2SO4 solution. The system measures nitrous oxide (N2O) 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 N2O reductase, which produces N2O 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 N-15 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 N-15 with GC/MS, offering greater convenience than IRMS.