土壤样品中氮同位素组成的元素分析仪-同位素质谱分析方法

建立了使用元素分析仪-同位素质谱(EA-MS)联用技术测定土壤样品氮同位素比值的方法。通过多组实验对比,讨论了不同实验条件对测定结果的影响,同时针对表土、黄土样品测定中易出现的积累效应、氧化能力下降及本底消除问题进行了探讨。结果表明:当Carrier-He载气流量在80～90mL/min,Conflo-He载气压力为84Pa,氧气喷量为100mL/min时,使用Cr2O3/Co3O4Ag氧化炉,严格控制样品残余和本底空白的条件下,土壤样品的测量精度为±0.3‰,满足测试要求。

Measurement of Nitrogen Isotopic Composition of Soil Samples by Element Analysis-Isotope Mass Spectrometry

Element analysis isotope mass spectrometry technology was applied to determine nitrogen isotope composition of sample from environmental and geological fields. In this work, the effect of suitable conditions for modern soils and loess samples measurement on experimental results were chiefly ascertained through comparisons. Moreover, the negative influences including uncompleted reaction of sample, baseline excursion and the decline of oxidation capacity in soil sample measurement were discussed. The results showed that the measurement precision of nitrogen isotopes can be less than ±0.3‰ with Cr 2O 3/Co 3O 4Ag oxidation furnace, 80—90 mL/min of carrier He flow rate, 84 Pa of Conflo He pressure and 100 mL/min of oxygen injection.