3 research outputs found
Speciation analysis of <sup>129</sup>I in seawater by carrier-free AgI-AgCl coprecipitation and accelerator mass spectrometric measurement
A rapid and simple method was developed for speciation analysis of 129I
in seawater by selective coprecipitation of carrier-free iodide and accelerator mass
spectrometry (AMS) measurement of 129I. Iodide was separated from seawater and
other species of iodine by coprecipitation of AgI with Ag2SO3, AgCl, and AgBr by
addition of only 100 mg/L Ag+ and 0.3 mmol/L NaHSO3 at pH 4.2−5.5. The
separation efficiency of iodide was more than 95%, and crossover between 129IO3− and
129I− fractions is less than 3%. Iodate and total inorganic iodine were converted to
iodide by use of NaHSO3 at pH 1−2 and then separated by the same method as for
iodide. Ag2SO3 in the coprecipitate was removed by washing with 3 mol/L HNO3 and
the excess AgCl and AgBr was removed by use of diluted NH3, and finally a 1−3 mg
precipitate was obtained for AMS measurement of 129I. The recovery of iodine species
in the entire procedure is higher than 70%. Six seawater samples collected from the
Norwegian Sea were analyzed by this method as well as a conventional anion-exchange
chromatographic method; the results from the two methods show no significant difference (p = 0.05). Because only one
separation step and fewer chemicals are involved in the procedure, this method is suitable for operation on board sampling
vessels, as it avoids the transport of samples to the laboratory and storage for a longer time before analysis, therefore significantly
improving the analytical capacity and reliability of speciation analysis of 129I. This improvement can stimulate oceanographic
tracer studies of 129I