The detection of129I by Inductively Coupled Plasma Mass Spectrometry (ICP/MS) in environmental samples can be used to determine anthropogenic
release of this long-lived radionuclide, which is a definitive indicator of certain nuclear activities. By using selective
precipitation techniques with on-line ICP/MS detection, low levels of129I can be detected. The major interference for the ICP/MS detection of129I is due the presence of natural129Xe found in water samples at a concentration of about 1 ng/ml. This work will demonstrate a instrument detection of less than
50 fg129I from environmental air samples and shows promise for a rugged ICP/MS technique to monitor129I levels in ambient air for nonproliferation monitoring purposes.