Exploiting dynamic reaction cell technology for removal of spectral interferences in the assessment of Ag, Cu, Ti, and Zn by inductively coupled plasma mass spectrometry

Analytical methods based on dynamic-reaction cell (DRC) technology using ammonia as a reaction gas have been developed for the determination of ultra-trace Ti, Zn, Cu and Ag by inductively coupled plasma mass spectrometry (ICP-MS). Challenging spectral interferences from complex matrices were demonstrated to be overcome by DRC, and several DRC approaches (on-mass and mass-shift) using ammonium (NH3) as a reaction gas were assessed and compared to the standard or “vented” mode analysis. Ammonium cluster ions were generated for Ti, Cu, Zn, and Ag (mass shift approach). The on-mass approach was also explored to take advantage of collisional focusing phenomena. In addition, DRC operating conditions were optimised by modifying NH3 gas flow rate and rejection parameter q (RPq). The optimised conditions were applied to show the usefulness of either on-mass or mass-shift approaches when removing Ca and P interferences. Finally, the sensitivity of all measurement modes was studied and excellent limits of detection (at few ng L−1 levels) were assessedThe authors wish to acknowledge the financial support of the Ministerio de Economía y Competitividad, Gobierno de España (project INNOVANANO, reference RT2018-099222-B-100), and the Xunta de Galicia (Grupo de Referencia Competitiva, grant number ED431C2018/19)S

Studies to evaluate methodologies used for determining heavy metal content in polyethylene terephthalate food packaging

Increased consumer awareness of contamination in food-contact packaging has raised global concerns due to the potential of environmental contamination from packaging upon disposal after the service lifetime. Contamination in virgin and recycled polymers used for food-contact packaging has necessitated the development of analytical methods that identify and quantify heavy metals. Heavy metal contaminants in food-contact plastics have the potential to cause health issues if leaching were to occur. Sample preparation and analytical methods were evaluated to quantify heavy metal content in polyethylene terephthalate (PET). Since PET is one of the most widely used polymers for food-contact applications, accurate quantification of heavy metal content is essential to ensuring consumer safety. The two published acid digestion methods yielded incomplete sample digestion of PET, thus, additional methods were required for proper PET analysis. To circumvent this, modified microwave-assisted acid digestion methods were developed, which result in complete PET digestion and produce visually clear solutions. Analysis of the complete PET digests by inductively coupled plasma-optical emission spectrometry (ICP-OES) resulted in lead and antimony content values statistically higher than the two previously mentioned methods. To evaluate the ability of non-destructive methods to quantify heavy metal content in PET food packaging, X-ray fluorescence (XRF) was compared with ICP. Traditional analytical methods such as ICP are time-consuming and expensive processes. Moreover, testing if XRF technology can provide a means for monitoring heavy metal content in thin plastics would greatly reduce the frequency of sample testing by traditional methodology. Results from this analysis suggests that it is possible to evaluate thin plastic samples by developing a statistical model that estimates ICP data from XRF outputs. This research shows that XRF technologies can be applied to online systems for real-time monitoring of heavy metal contamination in food packaging plastics. The results of these studies indicate that while food-packaging plastics should be regarded as safe, previously published research has underestimated the heavy metal contamination in polymers used for food packaging. This is of concern when considering end-of-life disposal for food packaging with regulatory threshold levels for specific and total heavy metal content

Method development for spent nuclear fuel characterization using isotope dilution HPIC-SF-ICP-MS

This PhD dissertation describes the development of an isotope dilution method, using sector field (SF) ICP-MS coupled with high pressure ion chromatography (HPIC), to determine the elemental mass fractions and nuclide specific compositions of U, Pu, Nd and Gd in spent nuclear fuel (SNF). Firstly, a method requiring less than 60 minutes for the separation of the elements of interest using HPIC was developed and validated. Secondly, the SF-ICP-MS data acquisition parameters and different calculation methods for isotope ratios were investigated to obtain the most precise isotope ratios from transient signals. Thirdly, the elemental mass fractions and nuclide specific composition of U, Pu and Nd in a UOx SNF and those of U, Pu, Nd and Gd in a “Gd fuel” were determined by using isotope ratios and isotope dilution HPIC-SF-ICP-MS. Finally, an overall uncertainty budget for isotope dilution HPIC-SF-ICP-MS was derived using the bottom-up approach. The isotope dilution HPIC-SF-ICP-MS method was compared with an existing ISO 17025 SNF characterization method, in which SNF components are isolated using gravitational ion chromatography followed by their analysis using TIMS and alpha spectrometry

Detailed state of the art review for the different on-line/in-line oil analysis techniques in context of wind turbine gearboxes

The main driver behind developing advanced condition monitoring (CM) systems for the wind energy industry is the delivery of improved asset management regarding the operation and maintenance of the gearbox and other wind turbine components and systems. Current gearbox CM systems mainly detect faults by identifying ferrous materials, water, and air within oil by changes in certain properties such as electrical fields. In order to detect oil degradation and identify particles, more advanced devices are required to allow a better maintenance regime to be established. Current technologies available specifically for this purpose include Fourier transform infrared (FTIR) spectroscopy and ferrography. There are also several technologies that have not yet been or have been recently applied to CM problems. After reviewing the current state of the art, it is recommended that a combination of sensors would be used that analyze different characteristics of the oil. The information individually would not be highly accurate but combined it is fully expected that greater accuracy can be obtained. The technologies that are suitable in terms of cost, size, accuracy, and development are online ferrography, selective fluorescence spectroscopy, scattering measurements, FTIR, photoacoustic spectroscopy, and solid state viscometers

Method development for the analysis of nuclear forensic signatures with ICP-MS

Nuclear forensic analysis is a field of analytical chemistry that focuses specifically on analyzing signatures of nuclear material for criminal investigation. Promising nuclear forensic signatures include rare earths element pattern and uranium and plutonium isotopes ratios. Uranium isotope ratios that deviate from natural indicates enrichment activities. The presence of plutonium and the 239Pu/240Pu isotopic ratio indicate irradiation of uranium for weapons production purposes. Samples for nuclear forensic analysis are often urgent, and therefore must be analyzed quickly, with good accuracy and precision. Robust methodologies must be developed for analysis of samples from potential nuclear scenarios with suitable speed, accuracy, and precision. In this dissertation, a method was developed to analyze uranium isotope ratios from solid particles on the surface of environmental swipe samples for the purpose of quickly and accurately determining whether uranium enrichment was occurring in the facility. A method to quantify rare earth impurities in uranium ore concentrates using high performance ion chromatography (HPIC) and inductively coupled plasma mass spectrometry (ICP-MS) was tested, as was a method to rapidly dissolve inorganic material using ammonium bifluoride and subsequently quantify the rare earth concentration using a newly developed high performance ion chromatography method coupled with ICP-MS detection. The method was demonstrated by accurate measurement of rare earth elements in igneous USGS minerals. Finally, the method was used to separate fresh fission products from a uranium tracer with detection by gamma ray spectroscopy.Includes bibliographical references