高分辨同位素质谱仪测定硝化-反硝化产物的15N丰度

Determination of N Abundance of Nitrification-Denitrification Products by High Resolution Isotope Mass Spectrometer

采用高分辨同位素质谱仪,结合现有实验室条件,建立了针对硝化、反硝化产物中15N2、15N2O、15NH3气体的同位素丰度进行直接定量化测定的检测方法。通过多组实验对比表明,在5~50 Pa压力范围内,采用优化后所得的质谱仪参数,三种气体15N同位素丰度测定结果的相对标准偏差(RSD)均<0.7%,同位素丰度测定结果与原料15N同位素标记硫酸铵试剂的标准丰度基本一致,满足检测要求。高分辨同位素质谱仪的应用,有效降低了测定过程中CO、CO2、H2O等杂质气体对15N2、15N2O、15NH3标记产物同位素丰度计算带来的干扰,提高了检测结果的准确度。

Using high-resolution isotope mass spectrometer,a set of detection methods for the direct quantitative determination of isotopic abundance of 15N2,15N2O,15NH3 in nitrification and denitrification products was established under the current laboratory conditions.Multiple sets of comparison experiments showed that in the pressure range of 5~50 Pa,the relative standard deviation(RSD)of 15N abundance measurement results are all<0.7%by using optimized mass spectrometer parameters.The results are basically consistent with the nominal abundance of ammonium sulfate reagent labeled by 15N isotope,which meets the testing requirements.The application of high-resolution isotope mass spectrometer effectively reduces the interference caused by the impurity such as CO,CO2 and H2O in the measurement for the isotope abundance of 15N2,15N2O and 15NH3 labeled products,and improves the accuracy of detection results.