Issue 5, 2015

Direct detection and isotope analysis of individual particles in suspension by single particle mode MC-ICP-MS for nuclear safety

Abstract

Isotopic fingerprint information carried by an individual particle is of great value in nuclear safety, nuclear safeguards, and nuclear environment. Several techniques, such as single particle mode ICP-MS, laser ablation ICP-MS and LA-MC-ICP-MS, have been developed for direct detection or isotope analysis of individual particles in the solid sample. In this study, single particle mode MC-ICP-MS was proposed for the precise isotopic measurement of individual particles in suspension. Erbium oxide powder with natural isotopic abundance used as uranium particle surrogate was dispersed in ultrapure water to prepare a suspension sample. Uranium isotope at different enrichment levels could be covered by the erbium isotope range. Erbium solution was nebulized before and after particle analysis to determine the mass bias factors in the mass spectrometer. The submicron-sized erbium particle was nebulized and then introduced into the ICP torch for detection and isotopic measurement in single particle mode. From the histogram of pulse intensities, the spherical equivalent physical diameter was estimated to be around 226 nm with 164Er amount of 7 × 10−16 g. Two data processing strategies, point by point (PBP) and linear regression slope (LRS), were used to determine the erbium isotope ratios. Results show that the precisions of 170Er/166Er, 168Er/166Er, and 167Er/166Er ratios determined by PBP method are 5.5%, 4.6% and 3.9%, respectively. The relative errors of these measured isotope ratios after mass bias correction lies between 0.2–4%. The precision and accuracy of 164Er/166Er ratio are worse due to the weak signal of 164Er. By LRS method, the precisions of determined 170Er/166Er, 168Er/166Er, 167Er/166Er and 164Er/166Er ratios improved by one order of magnitude at least. The precisions of 170Er/166Er, 168Er/166Er and 167Er/166Er ratios are better than 0.3%. The precision and accuracy of the 164Er/166Er ratio are significantly improved. Moreover, the 162Er/166Er ratio at 10−3 level could also be determined. The proposed technique is suitable for the detection and isotope analysis of particles with size range of 130 nm–3 μm. The sample preparation process is simple, which eliminates possible contamination. The technique combines fast screening, sensitive detection, and isotopic identification of an individual particle.

Graphical abstract: Direct detection and isotope analysis of individual particles in suspension by single particle mode MC-ICP-MS for nuclear safety

Article information

Article type
Technical Note
Submitted
13 10 2014
Accepted
11 12 2014
First published
11 12 2014

J. Anal. At. Spectrom., 2015,30, 1184-1190

Direct detection and isotope analysis of individual particles in suspension by single particle mode MC-ICP-MS for nuclear safety

S. Yongyang, W. Wei, L. Zhiming, D. Hu, Z. Guoqing, X. Jiang and R. Xiangjun, J. Anal. At. Spectrom., 2015, 30, 1184 DOI: 10.1039/C4JA00339J

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