A novel gas chromatography-combustion-isotope ratio mass spectrometry derivatization method for nitrogen isotope analysis of nitrate in water

文献类型： 外文期刊

第一作者： Li, An

作者： Li, An;Pan, Ligang;Dong, Jieqiong;Jin, Xinxin;Li, An;Pan, Ligang;Dong, Jieqiong;Jin, Xinxin;Chen, Qiusheng

作者机构：

期刊名称：RAPID COMMUNICATIONS IN MASS SPECTROMETRY （ 影响因子：2.419； 五年影响因子：2.439 ）

ISSN： 0951-4198

年卷期： 2018 年 32 卷 21 期

页码：

收录情况： SCI

摘要： Rationale: The stable nitrogen isotopic composition of nitrate (NO3-) can be an effective tool to identify NO3- sources and understand nitrogen cycling. However, the usefulness of this isotopic tool in environment research has been limited by complex analytical procedures for the nitrogen isotopic analysis of NO3-. We aimed to develop a novel method for the simple and rapid measurement of the delta N-15 value of NO3- in water. Methods: Water NO3- was transformed into nitrobenzene for nitrogen isotopic analysis by gas chromatography-combustion-isotope ratio mass spectrometry (GC/C-IRMS). The derivatization procedure was optimized to maximize the nitrobenzene yield. 1.5-fold 98% sulfuric acid and 0.5-fold benzene with respect to the water sample were used to derive nitrobenzene with only 1 min of vortex at room temperature. The nitrobenzene derivatization product (dissolved in benzene) was then separated by GC, followed by combustion to N-2 for delta N-15 analysis by IRMS. Results: The minimum amount of nitrogen required for accurate determination of the delta N-15 value was 8.6 ng at an m/z 28 intensity of 150 mV. The standard deviation of the GC/C-IRMS method was <= 0.5 (three replicates) even at a low NO3- concentration of 9.58 mg L-1. The various standards and samples with different delta N-15 values exhibited good agreement with the assigned delta N-15 values obtained by using the proposed method. Conclusions: Compared with previous methods, the newly developed method provided shorter analysis time and easy operation, and eliminated the need for the removal of chloride and nitrite. The GC/C-IRMS derivatization method offers a fully operational tool for delta N-15 measurement of NO3- in water.

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