The determination of trace elements, particularly rare earth elements, in uranium ore concentrates (UOCs) is important as the pattern can be indictive ore characteristics. Presented here is a methodology for accurately quantifying rare earth elements (REE) in UOCs. To improve the measurement uncertainty, isotope dilution mass spectrometry (IDMS) was utilized over other quantification techniques such as external calibration or standard addition. The isotopic determinations were measured by inductively coupled plasma-mass spectrometry (ICP-MS). To obtain high-fidelity isotopic measurements, separation of the REE from the uranium matrix was achieved by high-performance ion chromatography (HPIC), reducing the isobaric interferences. After separation, the target analytes were analyzed in two different modalities. For high precision analysis, the separated analytes were collected and measured by ICP-MS in an “offline” fashion. For a rapid approach, the separated analytes were sent directly into an ICP-MS for “online” analysis. These methods have been demonstrated to accurately quantify the REE content in a well-characterized UOC sample.

NiSO₄ and FeSO₄ self-assemble with heteroditopic ligands (L) comprising 2,2′-bipyridine and o-phenylene-(bis)urea cation- and anion-binding sites, respectively, into [ML₃SO₄] (M = Ni²⁺, Fe²⁺) triple-stranded ion-pair helicates and mesocates.

This study demonstrates a method for determining the isotopic composition of low-level (sub-pg) plutonium (Pu) directly from a cotton swipe. Environmental sample (ES) swipes are routinely employed as a tool for monitoring activities in nuclear facilities. Traditional ES swipe analysis, as employed in nuclear safeguards, utilizes laborious ashing, digestion, and chemical separation procedures prior to mass spectrometric (MS) analysis. Here, an innovative sample introduction technique employing a microextraction probe to extract Pu directly from the swipe surface is described. The microextraction probe lowers onto the swipe surface, seals on a small area (8 mm²), and delivers solvent (2% HNO₃) to extract actinide material that may be present. The extracted analyte is subsequently directed into a sector field inductively coupled plasma (ICP)-MS for isotope ratio determination. This microextraction-ICP-MS method successfully determined the isotopic composition (²⁴⁰Pu/²³⁹Pu and ²⁴²Pu/²³⁹Pu) of three Pu certified reference materials (CRM 136, 137, and 138) that were deposited (1 pg) onto ES swipes. The percent relative difference from the certified value, uncorrected for instrumental fractionation, was <2% for the ²⁴⁰Pu/²³⁹Pu ratio on all three CRMs and <10% for the ²⁴²Pu/²³⁹Pu ratio on CRM 136 and 138. The percent relative standard deviation, an estimate of the sample-to-sample isotopic precision, was <4% for the ²⁴⁰Pu/²³⁹Pu and <15% for the ²⁴²Pu/²³⁹Pu. Method limits of detection were determined, based on measurements of an enriched ²⁴⁴Pu material, to be ∼7 fg. Additionally, a mixed uranium (U) and Pu deposition was made to determine the method's ability to simultaneously extract U and Pu and determine the isotopic composition of both analytes.