Sampling systems for isotope-ratio mass spectrometry of atmospheric ammonia

Passive and active ammonia (NH3) sampling devices have been tested for their nitrogen (N) capture potential and delta N-15 fractionation effects. Several sampling techniques produced significantly different delta(15) NH3 signals when sampling the same NH3 source released from field site fumigation campaigns. Conventional passive NH3-Monitoring systems have shown to provide insufficient N for isotope-ratio mass spectrometry and various modified devices have been developed, based on existing diffusion tube designs, to overcome this problem. The final sampler design was then tested in a wind tunnel to verify that sampling NH3 in different environmental conditions did not significantly fractionate the delta N-15 signal. Copyright (c) 2005 John Wiley & Sons, Ltd.