Measurement of trace I in natural water with ozone reaction for effective separation of spectral interferences.

Tandem quadrupole inductively coupled plasma mass spectrometry has the potential capability to measure I at extremely low concentration if spectral interferences from Xe and IH can be eliminated effectively. Ozone was introduced as the reaction gas, resulting significantly improved reactions of (I→IO) and (I→IO ), and permitted the highly sensitive measurement of I as IO and IO , helping eliminate spectral interferences related to Xe and IH . In isotopic ratio (I/I) analysis by measuring (I→IO )/(I→IO ), a blank ratio of 6.7 × 10 can be realized for a solution of 500 μg/mL natural iodine, improved by one order of magnitude than the best performance previous reported. This technique contributes to the measurement of trace level I, a radionuclide of iodine attracting attentions as a geochemical tracer related to the development and civilian use of nuclear energy as well as a regulated radionuclide with guidance levels in drinking water established by the World Health Organization.