Rapid analysis of 129I in natural water samples using accelerator mass spectrometry

Abstract

A rapid and simple co-precipitation method for iodine separation from natural samples was developed for determination of 129 I using accelerator mass spectrometry (AMS). The method includes three steps, i.e. decomposition of organic iodine, iodine separation and target preparation using co-precipitation, and sensitive measurement of 129 I/ 127 I ratio using AMS. The recovery of iodine was higher than 90% for most natural water samples in the decomposition step using K2S2O8. Iodine in the digested sample was then co-precipitated as AgI-AgCl-Ag2SO3-Ag2SO4 with a typical recovery of 95-98%. It was observed that addition of 0.2 mg 127 I carrier can significantly improve the measurement uncertainty of low-level 129 I samples by enhancing iodine ion current. The overall recovery of iodine in the entire procedure was higher than 80%, and a detection limit of 1.0×10 5 atoms (or 2.2×10 -17 g) for 129 I was achieved. The developed method was validated by certified reference material (IAEA-418) and five types of natural water samples in comparison with results using the conventional solvent extraction method. Analytical results showed good agreement with the reference values for all samples, confirming the reliability of the developed method. The simple operation, with no need for organic solvent and small amount of iodine carrier addition make the developed method suitable for rapid and reliable determination of low level 129 I in natural water samples.

TARIM calcite: a potential reference material for laser ICPMS in situ calcite U–Pb dating

“…The lower intercept ages yielded by LA-(MC/Q)-ICPMS data show only a ∼2.3% variation among different pieces (Table 3). According to the two-step correction approach, 23,33 TARIM can also be used as a matrix-matched calcite material for determining U–Pb ages using LA-ICPMS though TARIM calcite has variable amounts of common Pb. 37–40 The ID-TIMS results also show a variable and relatively higher common Pb content than most laser dating results, possibly due to the few Pb-rich inclusions and cracks in some TARIM calcite pieces or fragments.…”

“…Detailed instrumental parameters and experimental conditions can be found in Table 1 and Zhang et al (2021). 33 202 Hg, 204 (Pb + Hg), 206 Pb, 207 Pb, and 208 Pb were acquired on ion counters with configurations: 202 Hg on IC4, 204 (Pb + Hg) on IC5, 206 Pb on IC2, 207 Pb on IC1B, and 208 Pb on IC6. 232 Th and 238 U were acquired simultaneously but separately on Faraday cups H3 on H4.…”

A zircon LA-ICPMS reverse depth profiling analysis method and its geological application

“…After ionization, charged ions were transported to a mass analyzer for U–Pb isotope and trace element analysis. 42…”

Apatite MAP-3: a new homogeneous and low common lead natural reference for laser in situ U–Pb dating and Nd isotope analysis

“…More details about instrumental and experimental parameters can be found in Zhang et al (2021). 53 The results for 202 Hg, 204 (Pb + Hg), 206 Pb, 207 Pb, 208 Pb, 232 Th, and 238 U were acquired simultaneously on different detector configurations: 202 Hg on IC4, 204 (Pb + Hg) on IC5, 206 Pb on IC2, 207 Pb on IC1B, 208 Pb on IC6, 232 Th on H3, and 238 U on H4. The integration time was set at up to 0.131 s. Instrument tuning was carried out on an NIST SRM 614 with a laser repetition of 6 Hz, energy density of 3 J cm −2 , and diameter of 75 μm to ensure 238 U signal intensities > 12 mv (750 000 cps).…”