Robert Clough

This review covers advances in the analysis of advanced materials, metals, fuels and lubricants, nanostructures, ceramics, refractories, organic and inorganic chemicals, catalysts and nuclear materials by a range of techniques including X-ray, ICP, LIBS, mass spectrometry, synchrotron-based techniques, plus non-destructive and ablation surface techniques.

This is the 18th Atomic Spectrometry Update (ASU) to focus on advances in elemental speciation and covers a period of approximately 12 months from January 2025. This ASU review deals with all aspects of analytical atomic spectrometry speciation methods developed for: the determination of oxidation states; organometallic compounds; coordination compounds; metal- and heteroatom-containing biomolecules, including metalloproteins, proteins, peptides and amino acids; and the use of metal tagging to facilitate detection via atomic spectrometry. As with all ASU reviews, the focus of the research reviewed includes those methods that incorporate atomic spectrometry as the measurement technique, although molecular detection techniques are also included where they have provided a complementary approach to speciation analysis. The number of publications covered this year has fallen to the lowest number since this ASU has been published. However, there is still a good breadth of elements covered, with the most popular elements still being As, Hg and Se, and the focus of many papers is on elucidating mechanisms and transformation pathways, particularly in plants and animals/humans, rather than concentrating on the speciation method. A number of papers covering speciation analyses of elements related to nuclear power generation have been published, which reflects the increasing demand for this power source in the global efforts to decarbonise. There has also been a report on the use of XRF spectroscopy as a detector for LC and three papers of note that describe comprehensive methods for metallobiomolecules. Once again, the quality of the abstract for many of the papers is poor, with detail on the methodology, key results with data included, conclusions and implications thereof missing. This is likely to lead to fewer researchers reading the article or considering it for reviews such as those produced by the ASU.

There is a regulatory need for reliable methods to quantify nanoparticles in biological samples for the hazard assessment and bioaccumulation potential of engineered nanomaterials (ENMs). Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is a promising technique, but its application is hindered by the lack of validated sample preparation procedures (e.g., solubilisation) and suitable biological reference materials. This study aimed to develop an in-house biological reference material for ENMs to support analytical method validation. Silver nanoparticles (Ag NPs) were introduced into rainbow trout via cardiac perfusion, with the gills and liver collected as target tissues. Tissues were homogenised using a blade grinder, followed by additional milling. Pre- and post-milling preparations were compared to evaluate the level of tissue processing required prior to SP-ICP-MS analysis. Tissue samples were solubilised using tetramethylammonium hydroxide before analysis. Background Ag NP concentrations in control tissues were low (0.2–0.7 × 10⁹ nanoparticles per g), consistent with previous studies. In contrast, fish exposed to Ag NPs showed a clear increase in particle concentration, reaching up to 33.8 ± 4.4 × 10⁹ nanoparticles per g, with median particle sizes of 74–81 nm. The additional milling significantly improved data quality. In the liver, nanoparticle concentrations increased from 10.7 ± 4.4 × 10⁹ nanoparticles per g before milling to 15.9 ± 1.4 × 10⁹ nanoparticles per g after milling. Precision also improved, with relative standard deviation (RSD%) reducing from 40.7% to 9.1%, and all nanoparticle metrics achieving RSD values below 15% after combined blade grinding and milling. These results demonstrate that perfusion, followed by blade grinding and milling, produces a homogenous in-house biological reference material containing ENMs. This approach is simple, cost effective, and ensures analytical robustness for SP-ICP-MS measurements. Future work should assess the material's shelf life and apply this approach in inter-laboratory testing to support broader method validation.

A range of leaching protocols have been used to measure the soluble fraction of aerosol trace elements worldwide, and therefore these measurements may not be directly comparable. This work presents the first large-scale international laboratory intercomparison study for aerosol trace element leaching protocols. Eight widely-used protocols are compared using 33 samples that were subdivided and distributed to all participants. Protocols used ultrapure water, ammonium acetate, or acetic acid (the so-called “Berger leach”) as leaching solutions, although none of the protocols were identical to any other. The ultrapure water leach resulted in significantly lower soluble fractions, when compared to the ammonium acetate leach or the Berger leach. For Al, Cu, Fe and Mn, the ammonium acetate leach resulted in significantly lower soluble fractions than those obtained with the Berger leach, suggesting that categorizing these two methods together as “strong leach” in global databases is potentially misleading. Among the ultrapure water leaching methods, major differences seemed related to specific protocol features rather than the use of a batch or a flow-through technique. Differences in trace element solubilization among leach solutions were apparent for aerosols with different sources or transport histories, and further studies of this type are recommended on aerosols from other regions. We encourage the development of “best practices” guidance on analytical protocols, data treatment and data validation in order to reduce the variability in soluble aerosol trace element data reported. These developments will improve understanding of the impact of atmospheric deposition on ocean ecosystems and climate.

This review covers advances in the analysis of advanced materials, metals, fuels and lubricants, nanostructures, ceramics, refractories, organic and inorganic chemicals, catalysts and nuclear materials by a range of techniques including X-ray, ICP, LIBS, mass spectrometry, synchrotron-based techniques, plus non-destructive and ablation surface techniques.

A range of leaching protocols have been used to measure the soluble fraction of aerosol trace elements worldwide, and therefore these measurements may not be directly comparable. This work presents the first large-scale international laboratory intercomparison study for aerosol trace element leaching protocols. Eight widely-used protocols are compared using 33 samples that were subdivided and distributed to all participants. Protocols used ultrapure water, ammonium acetate, or acetic acid (the so-called “Berger leach”) as leaching solutions, although none of the protocols were identical to any other. The ultrapure water leach resulted in significantly lower soluble fractions, when compared to the ammonium acetate leach or the Berger leach. For Al, Cu, Fe and Mn, the ammonium acetate leach resulted in significantly lower soluble fractions than those obtained with the Berger leach, suggesting that categorizing these two methods together as “strong leach” in global databases is potentially misleading. Among the ultrapure water leaching methods, major differences seemed related to specific protocol features rather than the use of a batch or a flow-through technique. Differences in trace element solubilization among leach solutions were apparent for aerosols with different sources or transport histories, and further studies of this type are recommended on aerosols from other regions. We encourage the development of “best practices” guidance on analytical protocols, data treatment and data validation in order to reduce the variability in soluble aerosol trace element data reported. These developments will improve understanding of the impact of atmospheric deposition on ocean ecosystems and climate.

A range of leaching protocols have been used to measure the soluble fraction of aerosol trace elements worldwide, and therefore these measurements may not be directly comparable. This work presents the first large-scale international laboratory intercomparison study for aerosol trace element leaching protocols. Eight widely-used protocols are compared using 33 samples that were subdivided and distributed to all participants. Protocols used ultrapure water, ammonium acetate, or acetic acid (the so-called “Berger leach”) as leaching solutions, although none of the protocols were identical to any other. The ultrapure water leach resulted in significantly lower soluble fractions, when compared to the ammonium acetate leach or the Berger leach. For Al, Cu, Fe and Mn, the ammonium acetate leach resulted in significantly lower soluble fractions than those obtained with the Berger leach, suggesting that categorizing these two methods together as “strong leach” in global databases is potentially misleading. Among the ultrapure water leaching methods, major differences seemed related to specific protocol features rather than the use of a batch or a flow-through technique. Differences in trace element solubilization among leach solutions were apparent for aerosols with different sources or transport histories, and further studies of this type are recommended on aerosols from other regions. We encourage the development of “best practices” guidance on analytical protocols, data treatment and data validation in order to reduce the variability in soluble aerosol trace element data reported. These developments will improve understanding of the impact of atmospheric deposition on ocean ecosystems and climate.

A range of leaching protocols have been used to measure the soluble fraction of aerosol trace elements worldwide, and therefore these measurements may not be directly comparable. This work presents the first large-scale international laboratory intercomparison study for aerosol trace element leaching protocols. Eight widely-used protocols are compared using 33 samples that were subdivided and distributed to all participants. Protocols used ultrapure water, ammonium acetate, or acetic acid (the so-called “Berger leach”) as leaching solutions, although none of the protocols were identical to any other. The ultrapure water leach resulted in significantly lower soluble fractions, when compared to the ammonium acetate leach or the Berger leach. For Al, Cu, Fe and Mn, the ammonium acetate leach resulted in significantly lower soluble fractions than those obtained with the Berger leach, suggesting that categorizing these two methods together as “strong leach” in global databases is potentially misleading. Among the ultrapure water leaching methods, major differences seemed related to specific protocol features rather than the use of a batch or a flow-through technique. Differences in trace element solubilization among leach solutions were apparent for aerosols with different sources or transport histories, and further studies of this type are recommended on aerosols from other regions. We encourage the development of “best practices” guidance on analytical protocols, data treatment and data validation in order to reduce the variability in soluble aerosol trace element data reported. These developments will improve understanding of the impact of atmospheric deposition on ocean ecosystems and climate.