Ion-exchange resin and denitrification pretreatment for determining δ15 N-NH4 + , δ15 N-NO3 - , and δ18 O-NO3 - values.

Our proposed method for removing anions using AG1-X8 resin, for isotopic analysis using denitrifying bacteria, and for concentrating samples containing low concentrations of NO3 - will make it possible to perform high-precision and accurate analyses easily and inexpensively. These methods are applicable not only to aerosols, but also to samples from diverse locations such as rivers, oceans, and Antarctica.