Improvement of the detection limit for determination of 129I in sediments by quadrupole inductively coupled plasma mass spectrometer with collision cell

Abstract

The previously developed sample introduction device for the hot extraction of iodine from environmental samples (soils or sediments) and on-line introduction of analyte via the gas phase in quadrupole inductively coupled plasma mass spectrometry with hexapole collision cell (ICP-CC-QMS) was equipped with a cooling finger, which allowed intermediate iodine enrichment and improved the detection limits for 129 I down to 0.4 pg g 21 without any additional sample preparation. A mixture of oxygen and helium as reaction gases in the hexapole collision cell was used for reducing the disturbing background intensity of 129 Xe 1 . Oxygen was also used as the carrier gas for iodine thermal desorption and transport into the ICP-CC-MS. The developed analytical method was applied for 129 I determination at the ultra-trace level and for isotope ratio measurements of 129 I/ 127 I down to 10 27 in contaminated sediments and in SRM 4357 (Ocean Sediment Environment Radioactivity Standard). The measured 129 I/ 127 I ratio of 5.3 6 10 27 corresponded to the expected value of 4.45 6 10 27 reported for this sediment in the certificate.

Critical comparison of radiometric and mass spectrometric methods for the determination of radionuclides in environmental, biological and nuclear waste samples

“…Besides the capability of being able to measurement low energy β -emitters, LSC also has the advantage of none or minimal selfabsorption, high counting efficiency, homogeneous distribution of the sample in the scintillation cocktail, relative simple sample preparation procedure, and easy standardization using internal or external standard. Another capability of LSC is the determination of isotopes decaying by emitting a high proportion of conversion electrons or by electron capture, such as 41 Ca and 55 Fe, which is carried out by the measurement of the Auger electrons produced during these decay processes.…”

“…AMS emerged in the late 1970s from nuclear physics laboratories and soon became used as an ultra-sensitive mass spectrometric technique for measuring isotopes of elements, and is now widely used for the determination of radionuclides, especially long-lived radionuclides, such as 3 H, 10 Be, 14 C, 26 Al, 32 Si, 36 Cl, 41 Ca, 53 Mn, 59 Ni, 129 I, 182 Hf, 210 Pb and actinides [31,71,72]. Almost all AMS facilities can be understood as two mass spectrometers (called "injector" and "analyzer") linked with a tandem accelerator.…”

“…Since not all elements form negative ions, isobaric interferences can be effectively suppressed in some important cases. In the case of 14 C, 41 Ca and 129 I, isobaric interferences are eliminated because 14 N, 41 K, and 129 Xe respectively do not form stable negative ions. The mass analyzed negative ions are then accelerated to the positive high-voltage terminal of a tandem accelerator where they encounter either a thin carbon foil or low pressure gas.…”

“…These inherent effects limiting the capability of isotope ratio measurements by TIMS can be considered by different internal calibration techniques or by using isotopic standard reference materials with well-known isotopic ratios for an element. Besides, U, Th and Pu, TIMS has also been used for many other radionuclides, such as 41 Ca, 241 Am, 242 Cm, 126 Sn, 226 Ra, 228 Ra [82,[90][91][92][93].…”

“…RIMS as a highly selective and sensitive mass spectrometric technique for ultratrace and isotope analysis has been used for the analysis of many radionuclides such as 41 Ca, 90 Sr, 99 Tc, 135 Cs, 210 Pb, 236 U, 238 Pu, 239 Pu, 240 Pu, 242 Pu, and 244 Pu in environmental, biological and waste samples [33,34,[94][95][96][97][98][99][100][101][102][103][104][105]. In RIMS the solid or liquid samples are vaporized and atomized by an atomic beam source (e.g.…”