A Novel Approach for the Simultaneous Determination of Iodide, Iodate and Organo-Iodide for ¹²⁷I and ¹²⁹I in Environmental Samples Using Gas Chromatography−Mass Spectrometry

Abstract

In aquatic environments, iodine mainly exists as iodide, iodate, and organic iodine. The high mobility of iodine in aquatic systems has led to (129)I contamination problems at sites where nuclear fuel has been reprocessed, such as the F-area of Savannah River Site. In order to assess the distribution of (129)I and stable (127)I in environmental systems, a sensitive and rapid method was developed which enables determination of isotopic ratios of speciated iodine. Iodide concentrations were quantified using gas chromatography-mass spectrometry (GC-MS) after derivatization to 4-iodo-N,N-dimethylaniline. Iodate concentrations were quantified by measuring the difference of iodide concentrations in the solution before and after reduction by Na(2)S(2)O(5). Total iodine, including inorganic and organic iodine, was determined after conversion to iodate by combustion at 900 °C. Organo-iodine was calculated as the difference between the total iodine and total inorganic iodine (iodide and iodate). The detection limits of iodide-127 and iodate-127 were 0.34 nM and 1.11 nM, respectively, whereas the detection limits for both iodide-129 and iodate-129 was 0.08 nM (i.e., 2pCi (129)I/L). This method was successfully applied to water samples from the contaminated Savannah River Site, South Carolina, and more pristine Galveston Bay, Texas.

Superoxide Production by a Manganese-Oxidizing Bacterium Facilitates Iodide Oxidation

“…This iodinated derivative was extracted with cyclohexane (Sigma) and quantified by gas chromatography-mass spectrometry (GC-MS) (Thermo Scientific). The detection limit for iodide was 0.34 nM (38). An analytical error of Ϯ10% for the iodide quantification technique was determined in this study (i.e., 1 M iodide); thus, iodide transformations of Ͻ10% cannot be distinguished from background and should be treated with caution.…”

“…Thus, losses in iodide concentrations were used to represent oxidized iodide in this study. Quantification of iodide concentrations were performed as described previously by Zhang et al (38). After the removal of cells by centrifugation (8,000 ϫ g for 20 min), iodide was oxidized to iodine by using 2-iodosobenzoate (Sigma) and subsequently iodinated with N,N-dimethylaniline (Sigma) to yield 4-iodo-dimethylaniline.…”

Distribution and source of 129 I, 239 ,240 Pu, 137 Cs in the environment of Lithuania

“…Procedure blank sample was prepared using the same procedure as the samples, and 129 I/ 127 I in the blanks were measured to be (2.2±0.3) ×10 -13 , which is 2 orders of magnitude lower than the samples. A detailed information about the procedure could be found in [38], [39].…”

Laboratory report on iodine (¹²⁹I and ¹²⁷I) speciation, transformation and mobility in Handford groundwater, suspended particles and sediments

“…The specific objectives were to determine: 1) the 127 I and 129 I speciation (iodide, iodate and organo-iodine) in the groundwater and explore the key factors that might affect the speciation; 2) the role of sediments, collected from different depths (vadose zone vs. saturated zone) and of different composition (silt vs. sand), in sequestering radioiodine, by assessing how the newly-introduced inorganic iodine partitions among the particulate (sediment, > 0.45 µm), colloidal (3 kDa-0.45 µm) and truly dissolved phases (<3 kDa); 3) iodine species transformation in the dissolved phases in the soil-water system and the remobilization of radioiodine during surface runoff, groundwater exfiltration/infiltration, storm-induced events. A newly-developed GC-MS technique (Zhang et al, 2010) was used to simultaneously measure 127 I and 129 I speciation in the groundwater. For the latter two objectives, our approach was to use 125 I as the analogue of 129 I, dosed at the average chemical concentration of 129 I, which was obtained from the first objective.…”

“…For the latter two objectives, our approach was to use 125 I as the analogue of 129 I, dosed at the average chemical concentration of 129 I, which was obtained from the first objective. The GC-MS technique (Zhang et al, 2010) and a liquid scintillation counting method was combined to simultaneously measure 127 I and 125 I in both aqueous and solid phases, which allowed us to compare the behavior of both isotopes in the same experiment. The intent of this research is to provide data that would provide input for making remediation decisions related to the >50 km 2 129 I plumes in the Hanford Central Plateau region.…”