An integrated automatic system to evaluate U and Th dynamic lixiviation from solid matrices, and to extract/pre-concentrate leached analytes previous ICP-MS detection

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.

Flow-through magnetic-stirring assisted system for uranium(VI) extraction: First 3D printed device application

A 3D printed solid-phase extraction (SPE) device for uranium(VI) extraction has been fabricated using stereolithographic 3D printing. The 3D printed device is shaped as a stirred reactor chamber containing a network of small cubes, which were impregnated with TEVA resin for the extraction of U(VI) from water matrices without doing any previous pretreatment. A flow-through system was combined with off-line ICP-MS detection for the accurate and rapid determination of U(VI) at trace levels. The automatic system was satisfactorily optimized using experimental design, obtaining 0.03 and 0.09 ng U(VI) of detection and quantification limits, respectively, and a durability of 11 consecutive extractions. The reliability of the proposed system was confirmed through the analysis of a reference water material (CSN/CIEMAT 2011), and to water samples (tap, mineral and groundwater) by addition/recovery assays obtaining recoveries between 95 and 106%. This study present for the first time the design of a 3D printing SPE device impregnated with TEVA resin for the on-line extraction of U(VI), showing that 3D printing is a powerful tool for simplifying the construction of complex experimental devices and its operation in analytical procedures for pretreatment applications in water matrices.

3D printed resin-coated device for uranium (VI) extraction

Laser-based stereolithography (SLA) 3D printing has been applied to construct a 3D printed device as support for uranium(VI) extraction, using a quaternary ammonium salt in liquid and solid form. As proof of concept, a simple process was carried out to immobilize a selective and commercial resin (TEVA resin), in all the surface area of the non-cured SLA 3D printed device, becoming immobilized after UV photocuring. Besides, a coat of Aliquat®336 covering the surface of the cured SLA 3D printed device was tested. Both 3D printed devices as supported for liquid and solid extractant were characterized. Better results in terms of precision were obtained by using TEVA resin (RSD 2.9%), which was satisfactory optimized, reaching a LOD of 0.03 ng U(VI), and a durability of 10 consecutive extractions, maintaining a recovery of 90% with 5% RSD. The 3D printed device is able to preconcentrate up to a sample volume of 30 mL, without any additional pretreatment. The uranium detection was performed with an ICP-MS. Satisfactorily results were obtained analyzing reference material, e.g. phosphogypsum and water matrices from intercomparison exercises, at a confidence level of 95%.