Direct determination of uranium and thorium in minerals by time-of-flight mass spectrometry with pulsed glow discharge

Abstract

A direct method of uranium and thorium determination in non-conducting geological samples using timeof-flight mass spectrometry with pulsed glow discharge was proposed. The following rock specimens were analysed: metamict zircon, metamict rinkite, metamict samarskite (Y-Fe-niobate), pyrochlore and jacinth.For sample sputtering a combined hollow cathode cell of high purity aluminium or tantalum hollow cathodes was used. Powdered or monolith samples were pressed into the surface of the powdered metal prior to analysis. Model samples (artificial mixtures of oxides) were proposed for calibration; additionally, relative sensitivity factors, internal standardisation and standard additions were employed.For validation, IAEA artificially prepared uranium ore reference material was analysed. For additional validation, the obtained results for real mineral samples were compared to the results of inductively coupled plasma optical emission spectrometry after sample dissolution and semi-quantitative data of energy dispersive X-ray spectrometry. Limits of detection (3s) for the designed method were 0.3 ppm for uranium and 0.5 ppm for thorium, which is comparable to laser ablation inductively coupled plasma mass spectrometry. The method was also tested for capability to measure isotope ratios for lead and uranium without specific isotope calibration. Acquired isotopic ratios of uranium and lead corresponded to their natural abundances within the experimental error.

New Possibilities for the Determination of Volatile Organic Compounds by Their Molecular Ions in Air Using µs-Pulsed GD TOFMS

“…The instrument and its analytical features were described previously. [8][9][10][11] The discharge cell included a copper hollow cathode and a sampler cone (anode). In the current study, the cathode of 6 mm inner diameter and 3.5 mm depth produced from high purity copper (99.999%) was used.…”

Total-reflection X-ray fluorescence determination of thorium and uranium in the presence of interfering elements in solid geological objects of natural and technogenic origin

“…[1][2][3] Nowadays, there are dozens of methods requiring chemical digestion prior to the quantitative determination of Th and U, namely, classical analytical methods, such as gravimetry, 4 spectrophotometry, 5 and modern instrumental methods, rst of all, inductively coupled plasma mass spectrometry and optical emission spectrometry (ICP-MS/OES). [6][7][8][9][10] These methods are widely used in the routine analysis, providing acceptable accuracy, but require time and reagent consuming sample preparation.…”

Uranyl Speciation on the Surface of Amidoximated Polyacrylonitrile Mats

“…In order to address these health hazards, there is a need for effective risk management for uranium contamination, which requires reliable rapid monitoring tools and exposure assessment for affected populations. Unfortunately, the complex nature of the environmental and biological matrices presents many challenges in U­(VI) detection due to the dependence of uranyl speciation on other ions, organic ligands, pH, and solid surfaces. − Thus, extensive precipitation reactions in acidic media and multistep cation/anion exchange extraction chromatography are employed prior to U­(VI) detection and quantification based on known radioanalytical methods, such as α spectroscopy, liquid scintillation counting, and inductively coupled plasma mass spectrometry. − These methods provide high sensitivity but require laboratory analysis and interpretation that use significant amounts of time and human resources. − In addition, adequate sampling strategies are important for the desert southwest, where monsoon season causes irregular heavy rain events that standard collection strategies may miss.…”