Determination of Nitrogen and Oxygen Isotopes in Nitrates: A Minireview

Nitrogen and oxygen isotope ratios (δ15N and δ18O) in nitrates are important in hydrology, oceanography, atmospheric chemistry, and agriculture. This paper reviews current isotope ratio mass spectrometry methods for the determination of nitrogen and oxygen isotopes in nitrates that include graphite combustion, AgNO3-ion exchange, Ba(NO3)2-acetone, two-step chemical conversion, bacterial approaches, and off-axis integral cavity output laser spectroscopy. This paper introduces the principles, processes, advantages, and disadvantages of these procedures. Future studies should focus on the determination of oxygen isotopes. The development of novel spectroscopic or other isotopic methodology may also be new research directions. In addition, in some nitrates, δ17O is more sensitive than traditional δ18O and further development for this isotope is of interest. In addition, the determination of δ17O may be used to more accurately evaluate δ18O.