Membrane entrance mass spectrometer based method for analyzing content of dissolved nitrogen isotope

Abstract

A membrane entrance mass spectrometer based method for analyzing content of dissolved nitrogen isotope comprises the following steps: 1, introducing helium into the liquid to be tested for 20 min to remove nitrogen dissolved in water; 2, adding an oxidant iodine hypobromite solution in the liquid to be tested with nitrogen removed to oxidize ammonia nitrogen into nitrogen; 3, determining a standard curve through a standard sample membrane entrance mass spectrometer; 4, measuring the liquid to be tested from the step 2 by the membrane entrance mass spectrometer, and calculating the content of nitrogen isotope in the ammonia nitrogen liquid; 5, removing the original ammonia nitrogen in the liquid to be tested treated in the step 2 by magnesium oxide, acidifying with sulfuric acid, then reducing nitrate to ammonia nitrogen by zinc powder, and then use the above step 2 to step 4 to obtain the content of nitrate nitrogen isotope in the solution. The method provided by the invention can fast and accurately measure and analyze the content of dissolved nitrogen isotope, and is conducive to promoting the application of nitrogen isotope tracer technique.

Description

technical field [0001] The invention relates to the technical field of isotope analysis, in particular to a method for analyzing dissolved nitrogen isotope content based on a membrane inlet mass spectrometer. Background technique [0002] Affected by the activities of industrial and agricultural production, a large amount of reactive nitrogen from anthropogenic sources has been input into the Earth's surface system. The enrichment of a large amount of reactive nitrogen in the earth's surface system has caused huge ecological and environmental hazards to aquatic ecosystems, such as water eutrophication, harmful algal blooms, and seasonal or permanent hypoxia. One of the most serious environmental problems facing mankind. Therefore, it is a hot scientific issue in the field of geosciences to study the biogeochemical cycle process and influence mechanism of nitrogen. Isotope tracer is currently the most ideal technique to study the transfer and transformation of nitrogen in a...

AI Technical Summary

Problems solved by technology

However, how to accurately and quickly analyze dissolved nitrogen (NH 4 + , NO 3 - ) isotope ratio has always been a major technical problem in the world, and it also greatly limits the application of nitrogen isotope tracer technology

Although NH in the water sample 4 + , NO 3 - After a series of biochemical reactions, the stable isotope mass spectrometer can be used to determine the isotope ratio between the two, but the problem is that (1) after tedious chemical reactions, the error of the experimental results is often beyond the acceptable range ; (2) The experimental analysis period is too long and time-consuming; (3) The analysis cost is expensive

At present, there is still no particularly effective experimental method to achieve direct and rapid analysis of the content of dissolved nitrogen isotopes

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