Rapid determination of 90Sr in seawater using a novel porous crown-based resin and tandem quadrupole ICP-MS/MS in cool plasma and O2-He mode

Abstract

There has been an increasing need for the rapid and automated analysis of ⁹⁰Sr in seawater for the purpose of radiological assessment and emergency response after the FDNPP accident. In this work, a rapid method for the determination of ⁹⁰Sr in seawater was established using ICP-MS/MS with cool plasma and collision-reaction gases combined with a new porous crown-based resin separation. A nanofiltration membrane was applied to rapidly pre-treat seawater samples within 3 min and remove most of the matrix components from 500 mL to 250 mL for the first time. A comprehensive investigation was performed to study the extraction behaviors of Sr, Zr, Ge, Y and matrix elements on the new resin, showing an excellent separation efficiency (> 10³) using a U-shaped resin column. Based on their different first ionization potentials, the ⁹⁰Zr⁺ and ⁸⁹Y⁺ interferences were completely eliminated under cool plasma conditions. The interferences of ⁷⁴Ge¹⁶O⁺ and ⁸⁸Sr were effectively suppressed by using 2 mL/min He-0.3 mL/min O₂ as the collision and reaction gases in the dynamic collision/reaction cell. Combined with chemical separation, the overall decontamination factors of Zr, GeO and Y were 1.9 × 10¹⁰, 6.9 × 10⁷ and 6.9 × 10⁷ respectively, and ⁸⁸Sr¹H₂⁺ tailing was reduced by more than 200 times compared to a conventional ICP-MS. A detection limit of 4.6 pg/L (24.0 Bq/L) for ⁹⁰Sr was achieved with a sample analysis turn-around time of 6 h for a set of 12 samples. The method was validated by analyzing spiked seawater samples.