Automated separation, preconcentration and measurement of 90Sr in liquid samples with complex matrices by online ion exchange chromatography coupled with inductively coupled plasma mass spectrometry (ICP-MS)

Automated and semi-automated packed sorbent solid phase (micro) extraction methods for extraction of organic and inorganic pollutants

In this study, the packed sorbent solid phase (micro) extraction methods from manual to automated modes are reviewed. The automatic methods have several remarkable advantages such as high sample throughput, reproducibility, sensitivity, and extraction efficiency. These methods include solid-phase extraction, pipette tip micro-solid phase extraction, microextraction by packed sorbent, in-tip solid phase microextraction, in-tube solid phase microextraction, lab-on-a-chip, and lab-on-a-valve. The recent application of these methods for the extraction of organic and inorganic compounds are discussed. Also, the combination of novel technologies (3D printing and robotic platforms) with the (semi)automated methods are investigated as the future trend.

Online solid-phase extraction-inductively coupled plasma-quadrupole mass spectrometric quantification of 90Sr using 88Sr/86Sr isotope dilution method

Due to the lack of a correlation with the natural Strontium (Sr) isotopes, it is difficult to apply the isotope dilution (ID) method to an artificial radioactive mononuclide Strontium-90 (⁹⁰Sr), in inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). Meanwhile, online solid-phase extraction (SPE)-ICP-QMS (SPE-ICP-QMS) serves as an automatic sequential analytical technique for measuring the ultra-trace amounts of radionuclides; however, apparent assay values obtained using this method are often negatively affected by differences in the sample matrix composition between standard and actual samples. In this study, the pg L^-1 level of ⁹⁰Sr was successfully measured by combining online SPE-ICP-QMS and the ID method with ⁸⁸Sr/⁸⁶Sr ratios in one sample injection, without the radioactive standard. Although naturally occurring abundant isobaric ⁹⁰Zr significantly influences ⁹⁰Sr quantification during mass spectrometry, consecutive separations between automated SPE and dynamic reaction cell (DRC) oxidation enable ⁹⁰Sr quantification, even in the presence of isobaric ⁹⁰Zr (acceptable down to 5.7 × 10^-9 of ⁹⁰Sr/Zr in sample solution), using this method. Through this method, both radioactive ⁹⁰Sr and naturally occurring Sr were simultaneously quantified using ⁸⁸Sr-to-⁸⁶Sr and ⁸⁸Sr-to-⁹⁰Sr ratios without radioactive ⁹⁰Sr standard solutions. This simultaneous quantification of stable Sr and ⁹⁰Sr was achieved within 15 min with good recovery rates. The limit of detection of ⁹⁰Sr was 1.1 pg L^-1 (equivalent to radioactivity 5.6 Bq L^-1) for a 10 mL injection. Finally, water collected from an actual contaminated water storage tank at the Fukushima Daiichi Nuclear Power Plant (Fukushima, Japan) was analyzed using the proposed method, and the obtained results agreed well with those obtained using conventional analytical methods.

Online Solid-Phase Extraction-Inductively Coupled Plasma-Quadrupole Mass Spectrometry with Oxygen Dynamic Reaction for Quantification of Technetium-99

Quantification of pg/L levels (i.e., 0.6 mBq/L) of radioactive technetium-99 (⁹⁹Tc) was achieved within 15 min in the presence of isobaric and polyatomic interference sources such as ruthenium-99 (⁹⁹Ru) and molybdenum hydride (⁹⁸Mo¹H) at 3-11 orders of magnitude higher concentrations. Online solid-phase extraction-inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) with oxygen (O₂) dynamic reaction cell (online SPE-ICP-MS-DRC) was shown to be a thorough automatic analytical system, circumventing the need for human handling. At three stepwise separations (SPE-DRC-Q mass filters), we showed that interference materials allowed the coexistence of abundance ratios of 1.5 × 10^-13 and 1.1 × 10^-5 for ⁹⁹Tc/Mo and ⁹⁹Tc/Ru, respectively. A classical mathematical correction using the natural isotope ratio of ⁹⁹Ru/¹⁰²Ru was used to calculate the residues of ⁹⁹Ru. Using this optimized system, a detection limit (DL; 3σ) of ⁹⁹Tc was 9.3 pg/L (= 5.9 mBq/L) for a 50 mL injection and sequential measurements were undertaken at a cycle of 24 min/sample. For the measurement of a lower concentration of ⁹⁹Tc, an AG1-X8 anion-exchange column was used to study 20 L of seawater. Its DL was approximately 1000 times greater than that of previous methods (70.0 fg/L). Thus, this method withstands coexistences of 5.8 × 10^-18 and 3.5 × 10^-9 for ⁹⁹Tc/Mo and ⁹⁹Tc/Ru, respectively. Spike and recovery tests were conducted for environmental samples; the resulting values showed good agreement with the spike applied.

A rapid, automated system for the separation, preconcentration and measurement of 90Sr, and U, Am and Pu isotopes

An online separation and preconcentration method, using an automated flow injection setup and solid phase extraction followed by ICP-MS/MS, was developed for the analysis of ⁹⁰Sr, and U, Am and Pu isotopes in various liquid sample matrices. The radionuclide analytes were separated from interferences and complex matrices using DGA-branched resin and Sr resin, then specific gases were used in the reaction/collision cell in the ICP-MS/MS to measure the different analytes. The system requires smaller sample volumes (10 mL), less sample preparation and shorter processing time (46 min per sample) compared to traditional radiometric and other MS techniques. Based on a 10 mL sample, the limits of detection were 1.48 pg L^-1 (8257 mBq L^-1) for ⁹⁰Sr, 1.75 pg L^-1 (0.40 mBq L^-1) for ²³⁴U, 0.65 pg L^-1 (77.65 mBq L^-1) for ²⁴¹Am, and 0.56 pg L^-1 (1.25 mBq L^-1) for ²³⁹Pu when all target analytes were measured in one analysis. The analytical figures of merit were evaluated for a range of sample matrices including lake water, seawater and urine and were comparable to those reported in the literature. This online system thus provides a novel, fully automated analytical tool with faster analysis time, smaller sample requirements, minimum sample preparation, low detection limits and the flexibility to handle single and multiple measurements of various radionuclides.