Iodine separation procedure for the determination of129I and127I in soil by neutron activation analysis

Progress on 129I analysis and its application in environmental and geological researches

“…Schematic diagram of the analytical procedure for separating microgram of carrier free iodine from solid and water samples for AMS measurement of 129 I (Adopted from [13] with permission from American Society of Chemistry). [13,37] temperature is increased to 850°C, and the gas flashing is changed from O 2 /N 2 to only O 2 and the temperature remains at 850°C for 1-2 h depending on the sample size [13,35]. At this condition, all species of iodine are converted to gaseous iodine and released from the sample, which are carried by flashing gases and trapped in a solution consisting of NaOH and NaHSO 3 .…”

“…In addition, the spectral interference from other radionuclides produced in neutron irradiation of major elements of the sample is another important issue for 129 I measurement using NAA. In general chemical separation and purification of pre-and post-irradiated samples are required, and many chemical procedures have been reported [23,[34][35][36]. The separated iodine from samples is normally converted to MgI 2 for neutron irradiation.…”

“…The separated iodine from samples is normally converted to MgI 2 for neutron irradiation. In some methods [34][35][36], the released iodine from combustion is trapped in active carbon, which is directly applied for neutron irradiation. Iodine in the irradiated samples is then further separated by solvent extraction and the separated iodide is finally precipitated as PdI 2 for gamma counting of 130 I using an HpGe detector.…”

Determination of 129I in environmental solid samples using pyrolysis separation and accelerator mass spectrometry measurement

“…Accelerator mass spectrometry (AMS) and radiochemical neutron activation analysis (RNAA) are the techniques for its determination in present environmental samples, and AMS is the only method for determination of 129 I in samples with 129 I/ 127 I lower than 10 -10 [4, [15][16][17]. Due to the limited sensitivity of RNAA, a large sample size (>20 soil or >50 L seawater of background samples) is normally needed for accurate determination of 129 I.…”

“…Effective separation of iodine from sample is a key issue for accurate determination of low-level 129 I in environmental samples. A number of methods such as alkali fusion [16], alkali leaching [18], acid digestion [19] and combustion [15,11,12,20] can be used to release iodine from the matrix of environmental solid samples and convert it into an aqueous solution. Among these sample, acid digestion and alkali leaching cannot completely release iodine from the sample matrix, because it does not completely decompose sample, causing iodine associated with mineral crystals 4 remaining in the sample residues, causing an unreliable analytical results for some samples.…”