Search

This update covers the literature published between approximately June 2022 and April 2023 and is the latest part of a series of annual reviews. It is designed to provide the reader with an overview of the current state of the art with respect to the atomic spectrometric analysis of various metals, chemicals and materials. Advances have been made in several areas. For cultural heritage scientists, it is worth noting that, after many years of inserting analytical data into chemometric tools in an attempt to elucidate provenance, several free to use algorithms that take an inexperienced analyst through the entire process have been developed. It is envisaged that such algorithms will also be developed for forensic samples. In other areas, there has been a big increase in papers reporting methods for analysing coals, with many of these applications employing LIBS. This increase is presumably a result of the use of coal increasing rapidly in some countries. The use of LIBS for analyses is still growing in many areas. For ferrous and non-ferrous metals, the development of more reliable calibration strategies for LIBs has been a common theme. The standoff ability of LIBS has also been put to good use in the nuclear industry and for the detection of explosives. Waste management of assorted materials, e.g. polymers, metals, etc. has also used LIBS analyses, often used in conjunction with chemometric data analysis tools. [ABSTRACT FROM AUTHOR]

Accurate, low-level measurement of the long-lived fission product 129I is important for waste characterisation and long-term monitoring of waste facilities and the surrounding environment. Inductively coupled plasma mass spectrometry (ICP-MS) is well-suited to high throughput, sensitive measurement of 129I as a cost-effective alternative to other mass spectrometric and decay counting techniques. Accurate 129I measurement by ICP-MS is affected by the multiple interferences on m/z = 129, necessitating multi-stage sample preparation and/or mathematical correction. This study assesses the capabilities of tandem ICP-MS/MS for rapid and routine measurement of 129I in nuclear wastes. The advantages of the tandem setup for removal of isobaric, polyatomic and tailing interferences are demonstrated, as are the improvements in sensitivity through matrix modification and the importance of selecting an appropriate internal standard. The optimised setup was applied to measurement of various decommissioning waste simulants following direct extraction of 129I. The procedure achieved an instrument detection limit of 1.05 × 10−4 Bq g−1 (0.017 ng g−1) for 129I, which is two orders of magnitude below the target out-of-scope limit of 0.01 Bq g−1 (1.57 ng g−1), with good agreement between ICP-MS/MS and liquid scintillation counting (LSC). The results show that rapid, routine, low-level measurement of 129I is achievable by ICP-MS/MS for end users in decommissioning and environmental monitoring. [ABSTRACT FROM AUTHOR]

This update covers the literature published between approximately June 2021 and May 2022 and is the latest part of a series of annual reviews. It is designed to provide the reader with an overview of the current state of the art with respect to the atomic spectrometric analysis of various metals, chemicals and materials. These materials include ferrous and non-ferrous metals, glasses, polymers, ceramics, engineered nanostructures, fuels, nuclear materials, building materials, catalysts and electronic components. Also included is the analysis of forensic samples such as explosives and gunshot residue. It is not a comprehensive review of all papers that have used an atomic spectrometric technique. Instead, it includes only those papers that have some novelty through making an advance in either knowledge or the application of atomic spectrometry. Those papers that maximise the information gleaned from analytical data, e.g. the provenance of cultural heritage or forensic samples, through the use of chemometric analysis will also be included. [ABSTRACT FROM AUTHOR]

This update covers the literature published between June 2020 and May 2021 and is the latest part of a series of annual reviews. It is designed to provide the reader with an overview of the current state of the art with respect to the atomic spectrometric analysis of various metals, chemicals and materials. It is not designed to be a comprehensive review of all papers that have used an atomic spectrometric technique. Instead, it includes only those papers that have some novelty through making an advance in either knowledge or the application of atomic spectrometry. Also included, especially for forensic-based applications, for recycling applications and for cultural heritage samples, are those papers that have treated the analytical data produced with chemometric packages to provide invaluable information on provenance or to aid identification. Other research has focussed on calibration strategies for LIBS analyses and improving the resolution of depth and lateral profiling to facilitate the elucidation of mechanistic aspects of electronic components. An additional topic of interest includes the identification of oxidation states and neighbouring atoms using techniques such as XPS and XANES, again attempting to elucidate mechanisms for electronic components or to elicit speciation data. [ABSTRACT FROM AUTHOR]

This review has been modified somewhat compared with its predecessors in that the cultural heritage applications have been grouped together in their own section rather than being split between assorted other sections throughout the review. Hopefully, this will enable readers interested in that topic to locate all of the relevant papers more easily. There is no doubting that laser induced breakdown spectrometry (LIBS) is still the most rapidly expanding technique of interest for "industrial" samples. Its use for on-line or standoff analysis covers many topic areas including the metals production, scrap metal and plastic sorting industries, nuclear applications, in situ analysis of remote systems, e.g. power cable insulators, etc. It is also regarded as being minimally damaging to samples and has therefore found extensive use in the analysis of cultural heritage samples; especially when used in conjunction with chemometric tools to identify provenance or chronology. For the analysis of fuels, it was disappointing to see so many papers re-inventing the wheel, with numerous applications being published that offer little improvement on existing standard methods. In many cases, the protocols described were very lengthy or complicated and succeeded only in obtaining a similar result to an existing method, but with poorer precision and with no benefit to the end user. Other areas, e.g. catalysts has a huge amount of interest. However, the techniques used to characterise the materials are mature and often, many of the papers published do not discuss the analytical science in any detail. The analysis of pharmaceuticals and personal care products has had a large increase in research interest during this review period. This is potentially because of traditional methods, e.g. atomic absorption, slowly being replaced by more modern techniques, e.g. ICP-MS. Other growth areas of research have been the analysis of thin films, semiconductors and solar cells. Here, it is often X-ray-based analytical methods that are most commonly used, although some depth-profiling applications will use either LIBS or LA-ICP-MS. Another very popular area of research is that of nanoparticles. Here, the research focus has shifted from toxicological studies to the analysis of nanoparticles being used as carriers for drugs. This area is likely to increase further over the coming years. Consequently, analytical methods have also changed from using field flow fractionation to X-ray-based techniques such as XPS and XANES that describe the chemical composition of the particles rather than their size. Single particle ICP-MS for particle sizing is still an area of interest though. [ABSTRACT FROM AUTHOR]

There has been a large increase in the number of papers published that are relevant to this review over this review period. The growth in popularity of LIBS is rapid, with applications being published for most sample types. This is undoubtedly because of its capability to analyse in situ on a production line (hence saving time and money) and its minimally destructive nature meaning that both forensic and cultural heritage samples may be analysed. It also has a standoff analysis capability meaning that hazardous materials, e.g. explosives or nuclear materials, may be analysed from a safe distance. The use of mathematical algorithms in conjunction with LIBS to enable improved accuracy has proved a popular area of research. This is especially true for ferrous and non-ferrous samples. Similarly, chemometric techniques have been used with LIBS to aid in the sorting of polymers and other materials. An increase in the number of papers in the subject area of alternative fuels was noted. This was at the expense of papers describing methods for the analysis of crude oils. For nanomaterials, previous years have seen a huge number of single particle and field flow fractionation characterisations. Although several such papers are still being published, the focus seems to be switching to applications of the nanoparticles and the mechanistic aspects of how they retain or bind with other analytes. This is the latest review covering the topic of advances in the analysis of metals, chemicals and materials. It follows on from last year's review 1–6 and is part of the Atomic Spectrometry Updates series. [ABSTRACT FROM AUTHOR]

Lysozyme is one of the most commonly used proteins for encapsulating gold nanoclusters, yielding Ly-AuNC complexes. While possible applications of Ly-AuNCs in environmental, biological and trace metal sensing in solution have been demonstrated, there is currently a poor understanding of the physical characteristics of the Ly-AuNC complex. In this study we have employed fully atomistic molecular dynamics simulations to gain an understanding of the formation of Au clusters within the protein. It was found that in order to form AuNCs in the simulations, an approach of targeted insertion of Au atoms at a critical surface residue was needed. Tyrosine is known to be crucial for the reduction of Au salts experimentally, and our simulations showed that Tyr20 is the key residue for the formation of an AuNC beneath the protein surface in the α-helical domain. It is hoped these observations will aid future improvements and modification of Ly-AuNCs via alterations of the alpha-helix domain or Tyr20. [ABSTRACT FROM AUTHOR]

Protein misfolding plays a critical role in the manifestation of amyloidosis type diseases. Therefore, understanding protein unfolding and the ability to track protein unfolding in a dynamic manner are of considerable interest. Fluorescence-based techniques are powerful tools for gaining real-time information about the local environmental conditions of a probe on the nanoscale. Fluorescent gold nanoclusters (AuNCs) are a new type of fluorescent probes which are ＜2 nm in diameter, incredibly robust and offer highly sensitive, wavelength tuneable emission. Their small size minimises intrusion and makes AuNCs ideal for studying protein dynamics. Lysozyme has previously been used to encapsulate AuNCs. The unfolding dynamics of lysozyme under different environmental conditions have been well-studied and being an amyloid type protein makes lysozyme an ideal candidate for encapsulating AuNCs in order to test their sensitivity to protein unfolding. In this study, we tracked the fluorescence characteristics of AuNCs encapsulated in lysozyme while inducing protein unfolding using urea, sodium dodecyl sulphate (SDS) and elevated temperature and compared them to complimentary circular dichroism spectra. It is found that AuNC fluorescence emission is quenched upon induced protein unfolding either due to a decrease in Forster Resonance Energy Transfer (FRET) efficiency between tryptophan and AuNCs or solvent exposure of the AuNC. Fluorescence lifetime measurements confirmed quenching to be collisional via oxygen dissolved in a solution which increases as the AuNC was exposed to the solvent during unfolding. Moreover, the longer decay component τ1 was observed to decrease as the protein unfolded, due to the increased collisional quenching. It is suggested that AuNC sensitivity to solvent exposure might be utilised in the future as a new approach to studying and possibly even detecting amyloidosis type diseases. [ABSTRACT FROM AUTHOR]

The use of LIBS continues to increase and many studies have been undertaken attempting to ensure maximum accuracy. This was especially true in the ferrous and non-ferrous metals sections where the spectra produced from the materials can be very line rich. Several papers described different mathematical algorithms to facilitate data handling. These included sequential backward selection – random forest, discriminant function analysis and genetic algorithms such as artificial neural networks. The use of such chemometric tools has also increased in sections including the analysis of cultural heritage samples, and the inorganic materials sections. In addition, it is still in common usage for dangerous samples, e.g. for explosives, nuclear materials etc. For the analysis of fuels, there is still a significant amount of wheel re-invention. Numerous papers are being published describing ‘research’, that are methods that have been in common usage in specialised fuels laboratories for some years. Sample preparation methods proved a popular area of research in this discipline. This is possibly a reflection of the necessity of analysing the different types of fuels now in common usage. The most recent pharmacopoeias are starting to describe the use of different atomic spectrometric techniques. There has therefore been an upsurge in the number of papers describing the analysis of pharmaceutical products. The lack of suitable reference materials for these and other organic-based sample types is problematic since method development has to rely largely on spike/recovery experiments. This review period has shown an increase in the number of papers using atomic spectrometry to elucidate mechanistic aspects of processes. This was especially true in the catalyst and electronic component sections. These studies frequently use several different techniques to obtain maximum information, e.g. oxidation state of the analytes, the surrounding chemical environment, bulk analysis etc. Foreword: this is the latest review covering the topic of advances in the analysis of metals, chemicals and materials. It follows on from last year’s review and is part of the Atomic Spectrometry Updates series. This year has seen several changes to the writing team, with John Marshall and Ian Whiteside retiring. We are very grateful for their years of service. We welcome Julia Waack and Rob Clough who have contributed to various sections. [ABSTRACT FROM AUTHOR]

This ASU review focuses on developments in applications of atomic spectrometry to the characterisation of metals, chemicals and materials. It is difficult to identify research trends solely from an annual review of the literature, but a certain perspective can be obtained from examining the developments described in recent years in this ASU review series. It is, for example, evident that there has been a decline in truly novel applications for the analysis of chemicals, perhaps indicative of the fact that, for most sample types, there is now an abundance of methods available in the literature. Those papers that have appeared in the year under review have either focused on specific problems not yet fully addressed (e.g. determination of Si in gasoline) or on incremental development of well-established approaches to sample preparation or measurement. Nevertheless, there has been a very noticeable increase in activity in relation to publication of methods for the characterisation of pharmaceuticals. This is directly linked to changes in the US Pharmacopeia requirements for registration of pharmaceuticals for human use that require assessments to be made for trace element content. Laser-induced breakdown spectrometry is becoming widely employed for applications involving the characterisation of a wide variety of metals, materials and other solid sample types. Efforts are being made to overcome the perceived weaknesses of the technique, such as lack of sensitivity, elemental fractionation, accuracy and/or precision. Advances have been made, for example, using dual-pulse lasers to improve sensitivity, or by employing chemometrics methods with full spectrum data to improve the robustness of calibration. Many of these reported LIBS developments draw from, and have relevance for, applications involving LA-ICP-MS, which continues to be a popular means of generating highly sensitive lateral and depth profiling and bulk compositional information for a wide range of materials and solids. The use of field portable instrumentation for in situ analysis continues grow, with LIBS and XRF techniques amongst those most frequently cited. The development of such instrumentation has had a substantial impact in the examination of cultural heritage artefacts, especially in relation to paintings, wall murals and other objects of unique historical value. The latter area of application has also seen continued use of combinations of surface (SIMS, XPS, SEM-EDS, PIXE, GD and laser ablation methods) and bulk (ICP-OES, ICP-MS, AAS, XRF) analysis techniques to reveal details of objects that would not otherwise be identified (for example preparatory sketches hidden under original works of art or materials provenance). This trend towards using a multi-technique based approach has also been apparent in the characterisation of multi-layer or heterogeneous organic and inorganic materials and metals. Finally, methods for the analysis of nanoparticles and nanostructures have been reported, based primarily on single particle (SP)-ICP-MS and flow field flow fractionation (A4F). The investigation of methods of drift correction, the use of flow injection and isotope dilution methodologies in combination with SP-ICP-MS are indicative of the further development of this field. [ABSTRACT FROM AUTHOR]

The efficient characterization of nuclear waste materials represents a significant challenge during nuclear site decommissioning, with a range of radionuclides requiring measurement in varied and often complex sample matrices. Of the available measurement techniques, inductively coupled plasma mass spectrometry (ICP-MS) has traditionally been applied to long-lived radionuclides, particularly in the actinide series. With recent advances in the technique, both the sensitivities achievable and number of radionuclides potentially measurable has expanded, with the reduced procedural time offering significant economic benefits to nuclear site waste characterization compared with traditional radiometric (typically alpha and beta spectrometry) techniques. This review provides a broad assessment of recent developments, improvements in capability and describes the advantages and drawbacks of ICP-MS with regards to sample introduction and instrument design. The review will be of interest to international agencies concerned with nuclear decommissioning as well as nuclear site laboratories, project managers and sites involved in environmental monitoring and nuclear forensics. [ABSTRACT FROM AUTHOR]