Blank experimental study on the determination of nitrogen and oxygen isotopes by chemical conversion method.

The reduction of nitrate to nitrous oxide by chemical conversion has the characteristics of simple operation and high sensitivity. Therefore, it is widely used in the pretreatment of nitrogen and oxygen isotopes. In this paper, a series of blank experiments were performed to determine various factors influencing the determination process for the chemical conversion method. To determine blank background values for reagents such as deionized water, NaCl and cadmium powder used in the experiment, the optimal experimental conditions of NaN, NaCl and cadmium powder were determined to maximize the nitrate reduction rate. The results showed that NaCl was burned at 450 °C for 48 hours, and the placement time was not more than one day, which could minimize the pollution introduced by NaCl. When 0.3 g of cadmium powder and 600 nmol of NaN were added, the overall reduction efficiency reached 90%. After measuring actual standard samples, the method demonstrated a good accuracy and applicability.