Centre for Stable Isotope Research and Analysis, University of Göttingen , 37077 Göttingen, Germany.
Thünen-Institut of Climate-Smart Agriculture , Bundesallee 50, 38116 Braunschweig, Germany.
Anal Chem. 2017 Jun 6;89(11):6076-6081. doi: 10.1021/acs.analchem.7b00724. Epub 2017 May 18.
An automated sample preparation unit for inorganic nitrogen (SPIN) coupled to a membrane inlet quadrupole mass spectrometer (MIMS) was developed for automated and sensitive determination of the N abundances and concentrations of nitrate, nitrite, and ammonium in aqueous solutions without any sample preparation. The minimum N concentration for an accurate determination of the N abundance is 7 μmol/L for nitrite and nitrate, with a relative standard deviation (RSD) of repeated measurements of <1%, and 70 μmol/L with an RSD < 0.4% in the case of ammonium. The SPIN-MIMS system provides a wide dynamic range (up to 3500 μmol/L) for all three N species for both isotope abundance and concentration measurements. The comparison of parallel measurements of N-labeled NH and NO from soil extracts with the denitrifier method and the SPIN-MIMS system shows a good agreement between both methods.
开发了一种用于无机氮（SPIN）的自动化样品制备单元，与膜进样四极杆质谱仪（MIMS）相结合，用于在无需任何样品制备的情况下自动且灵敏地测定水溶液中硝酸盐、亚硝酸盐和铵的 N 丰度和浓度。对于准确测定 N 丰度，亚硝酸根和硝酸盐的最小 N 浓度分别为 7 μmol/L，相对标准偏差（RSD）为<1%，而对于铵，最小 N 浓度为 70 μmol/L，RSD < 0.4%。SPIN-MIMS 系统为所有三种 N 物种的同位素丰度和浓度测量提供了宽动态范围（高达 3500 μmol/L）。土壤提取物中 N 标记的 NH 和 NO 的平行测量与反硝化方法和 SPIN-MIMS 系统的比较表明，两种方法之间具有良好的一致性。
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