Redox-Based Electrochemical Affinity Sensor for Detection of Aqueous Pertechnetate Anion

Abstract

Rapid, selective, and in situ detection of pertechnetate (TcO 4 − ) in multicomponent matrices consisting of interfering anions such as the ubiquitous NO 3 − and Cl − or the isostructural CrO 4 2− is challenging. Present sensors lack the selectivities to exclude these interferences or the sensitivities to meet detection limits that are lower than the drinking water standards across the globe. This work presents an affinity-based electrochemical sensor for TcO 4 − detection that relies on selective reductive precipitation of aqueous TcO 4 − induced by a 1,4-benzenedimethanethiol capture probe immobilized on an electrode platform. This results in a direct decrease in the electron transfer current, the magnitude of the decrease being proportional to the amount of TcO 4 − added. Using this approach, a detection limit of 1 × 10 −10 M was achieved, which is lower than the drinking water standard of 5.2 × 10 −10 M set by United States Environmental Protection Agency. The proposed approach shows selectivity to the TcO 4 − anion, allowing detection of TcO 4 − from a multicomponent groundwater sample obtained from a well at the Hanford site in Washington (well 299-W19-36) that also contained NO 3 − , Cl − , and CrO 4 2− , without discernably affecting the detection limits.

pH-Mediated Colorimetric and Luminescent Sensing of Aqueous Nitrate Anions by a Platinum(II) Luminophore@Mesoporous Silica Composite

“…Therefore, groundwater collected from the well 299-W19-36 at the nuclear waste site in Hanford, Washington was used for subsequent validation. The major inorganic constituents present in groundwater are listed in Supporting Information, Table S1, − among which NO 3 – has been reported as one of the dominant components (a concentration of 5.1 × 10 –03 M reported and validated by ion chromatography measurements). In these measurements, the luminescence response of the 1 ·PF 6 @CPG-383 sensor was tested upon its exposure to groundwater samples.…”

“…For practical demonstration of the sensor performance, a groundwater sample obtained from the well 299-W19-36 at the nuclear waste site in Hanford, Washington, USA, was used. The key constituents in groundwater are shown in Supporting Information, Table S1. − …”

Identification and Quantification of Technetium Species in Hanford Waste Tank AN-102

“…Tc can adopt multiple oxidation states (typically in solution +I through +VII) and exhibits complicated redox and coordination chemistry. − Therefore, identifying chemical and redox speciation of Tc in the Hanford tank waste and quantification of the components will enable projection of its distribution between waste fractions and behavior during processing and support effective treatment and immobilization alternatives such as grouting for safe waste storage and disposition. It will also assist in designing more effective methods of their detection, which has thus far primarily focused on TcO 4 – . − …”