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Seven plant certified reference materials (NIST SRM1515 Apple Leaves, NIST SRM1547 Peach Leaves, BCR-129 Hay Powder, BCR-670 Aquatic Plant, GBW07603 Bush Twigs and Leaves, GBW10015 Spinach Leaves and NCS ZC73036a Green Tea) were analysed for their mass fractions of 48 elements by inductively coupled plasma tandem-mass spectrometry (ICP-MS/MS): Li, Be, Na, Mg, Al, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Rb, Sr, Y, Nb, Mo, Ag, Cd, Sb, Te, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ta, Tl, Pb, Bi, Th, U. Special focus was put on the determination of technology-critical elements (TCEs), to which, e.g. Li, Be, Ga, Ge, Nb, Sb, Ta, Tl, Bi, and the rare-earth elements (REEs, lanthanides and Y) are counted. Closed-vessel microwave digestion was performed using HNO3, H2O2 and HBF4. The average bias for certified values is − 1% ± 13% (SD). Limits of detection (xL) in the measured solutions lie between 13 fg g−1 (Tb) and 52 ng g−1 (Ca). This article seeks to provide an optimised measurement procedure for the determination of element mass fractions of emerging importance in environmental samples, which are challenging to analyse with more traditional techniques such as single-quad ICP-MS. In addition, it aims to improve the characterisation of commonly used plant reference materials by providing mass fraction data for rarely studied elements. Graphical abstract

Gas cell interactions of 73 elements with nitrous oxide (N2O) have been evaluated using inductively coupled plasma tandem mass spectrometry (ICP-MS/MS). Recommendations for the reduction of interferences are provided.

In inductively coupled plasma mass spectrometry, the most abundant Ca isotope (40Ca) suffers from isobaric interference with argon, hindering the potential for low detection limits of Ca. A powerful approach is to remove the interference by using a reaction gas in a reaction cell. Ammonia (NH3) has proven to be an effective reaction gas by process of a charge transfer reaction. However, NH3 is highly corrosive and toxic and cannot remove isobaric 40 K. Therefore, this work proposes the use of nitrous oxide (N2O) to mass shift the target analyte 40Ca to 40Ca16O+ as a non-corrosive and non-toxic alternative. Instrument performance testing demonstrated that N2O was capable of reaching equivalent detection limits (0.015 ng g−1) and background equivalence concentrations (0.041 ng g−1) to that of NH3 and limited by the blank only. Further investigation of matrix interferences with synthetic standards highlighted that the N2O approach supports the separation of potassium (K) and magnesium (Mg)–based interferences at tested concentrations of more than 600 times and almost 800 times higher than Ca respectively, whereas NH3 was found to only support the removal of Mg. This work highlights a clear advantage of N2O for low-level Ca determinations with high matrix loads, as well as compatibility with other instrumentation sensitive to corrosion that supports reaction cell technology. Graphical abstract

In inductively coupled plasma mass spectrometry, the most abundant Ca isotope (

Knowledge of the uptake and fate of mercury (Hg) compounds in biota is important in understanding the global cycling of Hg and its transfer pathways through food chains. In this study, we analysed total mercury (T-Hg) and methylmercury (MeHg) concentrations in 117 livers of Scottish birds of prey that were found across Scotland and submitted for post-mortem examination through the Raptor Health Scotland project between 2009 and 2019. Statistical comparisons focussed on six species (barn owl, Tyto alba; Eurasian common buzzard, Buteo buteo; golden eagle, Aquila chrysaetos; hen harrier, Circus cyaneus; Eurasian sparrowhawk, Accipiter nisus; and tawny owl, Strix aluco) and showed that golden eagles had a statistically lower fraction of MeHg compared to other raptor species. Further investigation using stable carbon and stable nitrogen isotope ratio measurements carried out for the golden eagles (n = 15) indicated that the increased presence of inorganic mercury (iHg) correlated with a marine influence on the primarily terrestrial diet. Additional bioimaging (n = 1) with laser ablation – inductively coupled plasma – mass spectrometry indicated the co-location of Hg and selenium (Se) within the liver tissue and transmission electron microscopy showed evidence of nanoparticles within the range of 10–20 nm. Further analysis using single particle – inductively coupled plasma – mass spectrometry (n = 4) confirmed the presence of Hg nanoparticles. Together, the evidence suggests the presence of mercury selenide (HgSe) nanoparticles in the liver of some golden eagles that, to our knowledge, has never been directly observed in terrestrial birds of prey. This study points to two alternative hypotheses: these golden eagles may be efficient at breaking down MeHg and form HgSe nanoparticles as a detoxification mechanism (as previously observed in cetaceans), or some golden eagles with elevated iHg may have accumulated these nanoparticles by foraging on stranded cetaceans or seabirds.

Correct handling and preservation of water samples is crucial to ensure their integrity for arsenic speciation measurements. ISO TS 19620:2018 is a method for the determination of arsenic(iii) and arsenic(v) species in waters by liquid chromatography (LC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) or hydride generation atomic fluorescence spectrometry (HG-AFS). During the development of this method, a study was performed to establish the best practices for storage and preservation of samples to maintain the integrity of the arsenic speciation and stability. Four arsenic species were studied: arsenite (As(iii)), arsenate (As(v)), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in three different water types: deionised water, mineral water and natural river water. The effect of sample bottle material, light, storage temperature, and acidification were evaluated. When samples are acidified and refrigerated, they can reliably be stored for up to 12 weeks without significantly affecting the arsenic concentration and speciation. The sample bottle material and light had no affect on the speciation integrity or stability.

Impact of zero valent iron (Fe°) amendment on grain-yield (GY) and grain-As and Cd accumulation in rice (Oryza sativa L.) cultivars Kilombero and Faya were investigated. Rice plants were amended with Fe° dosages of 0, 3.1, 6.2, and 12.4 g Fe°/kg soil in pots in greenhouse experiments under continuous flooding water regime. GY in each treatment was determined at maturity, grain-As and Cd and arsenic species concentrations were determined using ICP-MS and HPLC tandem ICP-MS respectively. Mean GY in Faya (5.5 ± 1.0 g/plant) and Kilombero (4.2 ± 0.4 g/plant) amended with at least 6.2 g Fe°/kg soil were at least 57% and 22% respectively significantly higher (F = 11; p = 0.003) than that in controls (3.7 ± 0.6 and 3.4 ± 0.4 g/plant). For As bioaccumulation, mean grain-As concentration in Faya T2 (≤227 ± 32 μg/kg) and Kilombero (≤218 ± 25 μg/kg) amended with at least 6.2 g Fe°/kg soil in were at least 83% and 77% respectively significantly lower (F = 7; p = 0.004) than that in controls (973 ± 43 μg/kg and 1278 ± 208 μg/kg). Mean grain-Cd concentrations in Faya (10 ± 2 μg/kg) and Kilombero (13 ± 3 μg/kg) amended with corresponding Fe° dosages were at least 26% and 39% significantly lower (F = 4; p0.05) than that in controls (18 ± 3 and 23 ± 1 μg/kg). Results indicated that amending Kilombero with at least 6.2 g/kg Fe° effectively optimally regulated both grain-As and Cd accumulation to values lower than the European Commission's legislated maximum contaminant limits (MCL) of 200 μg/kg without negating grain yield benefits. Our results suggest that bioaccumulation of both As and Cd in rice grains may be completely circumvented by adopting cultivar-specific Fe° amendment dosage.

Impact of soil type, soil-metal(loids) and soil-pH of rice paddies on grain-arsenic (As) and cadmium (Cd) accumulation in Malawian rice was investigated to explore the extent to which Malawi's geographical location, soil types, soil-metal(loids) and soil-pH and their interactions impact on grain-As and Cd accumulation. Multivariate techniques were used to evaluate the relationships among measured parameters. Results showed that the 1st three principal components consisting of soil-types, soil-metal(loids) and soil-pH explained 83% of total variance of both grain-As and Cd accumulation. For As, highest grain-As was detected in rice from central region (CR) cultivated in vertisols characterized with soil-As ≥ 2.5 mg/kg and soil-pH > 7.0 whereas the lowest was in rice from northern region (NR) cultivated in fluvisols characterized with soil-[As] ≤ 1.5 mg As/kg soil and soil-pH range of 6.00–6.99. For Cd, highest grain-Cd was detected in rice from CR cultivated in luvisols with soil-As range of 2.0–3.0 mg/kg and soil-pH

Three isomeric methyl­ated 2-(thio­phen-2-yl)acetohydrazides show little consistency in the pattern of weak (C—H⋯O, C—H⋯π and π–π) inter­actions in their crystal structures., The crystal structures of three isomeric (E)-N-methyl-N′-(nitro­benzyl­idene)-2-(thio­phen-2-yl)acetohydrazides (formula C14H13N3O3S) are described, with the nitro group in ortho, meta and para positions in the benzene ring. In each crystal structure, mol­ecules are linked by various weak inter­actions (C—H⋯O and C—H⋯π bonds, and π–π stacking), leading to three-dimensional networks in each case, but with little similarity between them.

Reliable, fast and cost efficient mercury analysis is paramount to assess Hg levels in a huge variety of matrices, from soil and water to a variety of foodstuffs. In this work, a novel concept was adopted for seafood and hair analysis, which combines a simplified methylmercury extraction and photochemical vapour generation of Hg0 with liquid chromatography and atomic fluorescence spectrometry (LC-AFS). This concept reduces the number of reagents required to methanol and APDC for extraction and separation of Hg species, and acetic acid, which when combined with UV generates volatile Hg0 in one single step. Here, we compare conventional chemical vapour generation (CVG) with photochemical vapour generation (PVG) for seafood and hair matrix. Our results show that the LC-PVG-AFS method offers lower detection limits and higher precision than that of LC-CVG-AFS measurements by a factor of two. The extraction and LC-PVG-AFS technique was validated using 7 seafood and hair reference materials, yielding methylmercury recoveries of 93.2% to 105%. Further validation was carried out by comparing results from methylmercury determination in 14 tuna samples by the LC-PVG-AFS method to results obtained by GC-AFS, showing R2 = 0.98 and a gradient of 1.0077, which indicates good correlation between the newly developed LC-PVG-AFS technique to an already validated GC-AFS method.