<i>In Situ</i> Quantification of [Re(CO)₃]⁺ by Fluorescence Spectroscopy in Simulated Hanford Tank Waste

A pretreatment protocol is presented that allows for the quantitative conversion and subsequent <i>in situ</i> spectroscopic analysis of [Re­(CO)₃]⁺ species in simulated Hanford tank waste. In this test case, the nonradioactive metal rhenium is substituted for technetium (Tc-99), a weak beta emitter, to demonstrate proof of concept for a method to measure a nonpertechnetate form of technetium in Hanford tank waste. The protocol encompasses adding a simulated waste sample containing the nonemissive [Re­(CO)₃]⁺ species to a developer solution that enables the rapid, quantitative conversion of the nonemissive species to a luminescent species which can then be detected spectroscopically. The [Re­(CO)₃]⁺ species concentration in an alkaline, simulated Hanford tank waste supernatant can be quantified by the standard addition method. In a test case, the [Re­(CO)₃]⁺ species was measured to be at a concentration of 38.9 μM, which was a difference of 2.01% from the actual concentration of 39.7 μM

Crystallographic and Spectroscopic Characterization of Americium Complexes Containing the Bis[(phosphino)methyl]pyridine-1-oxide (NOPOPO) Ligand Platform

The crystal structures of americium species containing a common multifunctional phosphine oxide ligand, reported for its ability to extract f elements from acidic solutions, namely, 2,6-[Ph₂P­(O)­CH₂]₂C₅H₃–NO, <b>L</b>, were finally determined after over three decades of separations studies involving these species and their surrogates. The molecular compounds Am­(<b>L</b>)­(NO₃)₃, <b>Am 1:1</b>, and [Am­(<b>L</b>)₂(NO₃)]­[2­(NO₃)], <b>Am 2:1</b>, along with their neodymium and europium analogues, were synthesized and characterized using single-crystal X-ray crystallography, attenuated total reflectance Fourier transform infrared spectroscopy, and luminescence spectroscopy to provide a comprehensive comparison with new and known analogous complexes

In Situ Spectroscopic Analysis and Quantification of [Tc(CO)₃]⁺ in Hanford Tank Waste

The quantitative conversion of nonpertechnetate [Tc­(CO)₃]⁺ species in nuclear waste storage tank 241-AN-102 at the Hanford Site is demonstrated. A waste sample containing the [Tc­(CO)₃]⁺ species is added to a developer solution that rapidly converts the nonemissive species into a luminescent complex, which is detected spectroscopically. This method was first demonstrated using a [Tc­(CO)₃]⁺ sample of nonwaste containing matrix to determine a detection limit (LOD), resulting in a [Tc­(CO)₃]⁺ LOD of 2.20 × 10^–7 M, very near the LOD of the independently synthesized standard (2.10 × 10^–7 M). The method was then used to detect [Tc­(CO)₃]⁺ in a simulated waste using the standard addition method, resulting in a [Tc­(CO)₃]⁺ concentration of 1.89 × 10^–5 M (within 27.7% of the concentration determined by β liquid scintillation counting). Three samples from 241-AN-102 were tested by the standard addition method: (1) a 5 M Na adjusted fraction, (2) a fraction depleted of ¹³⁷Cs, and (3) an acid-stripped eluate. The concentrations of [Tc­(CO)₃]⁺ in these fractions were determined to be 9.90 × 10^–6 M (1), 0 M (2), and 2.46 × 10^–6 M (3), respectively. The concentration of [Tc­(CO)₃]⁺ in the as-received AN-102 tank waste supernatant was determined to be 1.84 × 10^–5 M