Determination of 17O Anomaly in Atmospheric Aerosol Nitrate

Abstract A novel method for rapid determination of oxygen isotope anomaly (Δ17O) in atmospheric aerosol samples was developed. With this method, the measurement was completed in 15 min with a relatively high analytical precision and a low determination limit. To achieve an analytical precision of 0.6‰, this method required a minimum nitrate content of 29 nmol (0.4 μg N). The analytical precision was optimum with a nitrate content of 57 nmol (0.8 μg N). The nitrate in atmospheric aerosol samples was converted to nitrous oxide by optimized bacterial denitrification process within 4 hs. After that, a thermal decomposition of nitrous oxide in sample gas was carried out in a gold tube at 800 °C after separation and purification, followed by gas chromatographic separation and isotope analysis of oxygen. The experiment results showed that the analytical precision of Δ17O in this method could reach 0.19‰ with a sample content of 57 nmol NO3−, and the analytical precision of δ15N could reach 0.15‰. This method was not only suitable for oxygen isotope anomaly determination in atmospheric aerosol samples, but also for the other atmospheric environmental samples such as rain and snow samples with low concentrations.