Peroxide Digestion Research Articles

Multivariate Optimization of a Green Microwave-Assisted Hydrogen Peroxide Digestion of Vegetable Oils and Subsequent Elemental Determination Via Inductively Coupled Plasma–Optical Emission Spectrometry

AbstractA microwave-assisted digestion technique based on dilute hydrogen peroxide (MW-AHPD) was developed for multielemental determination in vegetable oils. The determination of ten trace elements (As, Cd, Cr, Cu, Fe, Pb, Ni, Sn, V, and Zn) was conducted via inductively coupled plasma optical emission spectroscopy (ICP-OES) after digestion. The most influential parameters were investigated by using multivariate optimization tools (two-level full factorial and central composite design) with percent recovery as the chemometric response. The optimum conditions were 2.0 mol L−1 (H2O2]), 156 °C (digestion temperature), 0.1 g (sample mass) and 50 min (digestion time). Under the optimized conditions, the efficiency of digestion was evaluated based on the residual carbon content (RCC) of the final digests. The RCC values were very low, ranging from 0.84 to 1.60% (m/m). The greenness of the technique was evaluated using the Analytical Eco-scale, and the proposed method was considered an excellent green analysis method with a final score of 90. The accuracy of the optimized MW-AHPD was evaluated by spiking sunflower, olive, and peanut oils at concentrations of 2.5 and 5.0 μg L−1, and excellent recoveries between 90.3 and 107.3% were reported. The accuracy of the MW-AHPD method was compared with that of microwave-assisted digestion using concentrated HNO3, and there was no significant difference between the two methods. The limits of detection ranged from 0.026 to 14.6 μg L−1. On the other hand, the interday and intraday precisions were less than 6.67 and 6.96%, respectively. The method was successfully applied to determine the concentrations of trace elements in 5 vegetable oils on the South African market. Thus, MW-AHPD-ICP–OES is applicable for the determination of trace elements in vegetable oils.

Novel Microwave Assisted-Hydrogen Peroxide Digestion of Coal and Fuel Oils Using Methionine as a Capping Reagent for the Determination of Mercury by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES)

A novel analytical method was developed for quantifying total mercury in fuel oils using methionine as a capping reagent. Methionine was added to fuel and standard solutions as a preserving agent before microwave-assisted hydrogen peroxide digestion (MW-AHPD). To the best of our knowledge, it is the first-time methionine was used as a capping reagent for the total determination of mercury in fuel oils using ICP-OES with a pneumatic nebulizer. Multivariate optimization tools (two-level half factorial and central composite design) were used to investigate the most influential parameters of the MW-AHPD method. The best conditions were 0.1 g sample mass, 5 mol L−1 [H2O2], 5. 95 mol L−1 [methionine], 36 min and 200 °C with accepted trueness (93–107%) and precision (1.94%). The developed MW-AHPD procedure provided a coefficient of determination (R2) of 0.9989, limit of detection (LOD) of 0.25 µg L−1 and limit of quantification (LOQ) of 0.8 µg L−1. The newly developed MW-AHPD procedure was validated using hydride generation-ICP-OES and there was no statistical difference at 95% confidence level between the newly developed method and the standard protocol. Therefore, the newly developed MW-AHPD procedure was applied with coal, crude oil, gasoline, diesel oil, and kerosine samples and the concentration levels were from 0.876 ± 0.023 to 0.938 ± 0.082 µgg−1, 0.383 ± 0.043 to 0.506 ± 105 µgg−1, 0.306 ± 0.010 to 0.390 ± 0035 µgg−1, 0.360 ± 0.003 to 0.431 ± 0.001 µgg−1 and < DL, respectively.

Occurrence and abundance of microplastics and plasticizers in landfill leachate from open dumpsites in Sri Lanka

This is the first attempt that investigate the abundance of plasticizers in leachate sediment in the scientific literature, alongside the debut effort to explore the abundance of microplastics and plasticizers in landfill leachate and sediment in Sri Lanka. Microplastics in sizes ranging from ≥2.0–5.0, ≥1.0–2.0, and ≥ 0.5–1.0 mm were extracted from the leachate draining from ten municipal solid waste open dump sites and sediment samples covering seven districts. Microplastics were extracted by density separation (Saturated ZnCl2) followed by wet peroxide digestion and the chemical identification was conducted by Fourier Transform Infrared spectroscopy. Plasticizers were extracted to hexane and analyzed by high-performance liquid chromatography. The total mean microplastic abundance in leachate was 2.06 ± 0.62 mg/L whereas it was 363 ± 111 mg/kg for leachate sediments. The most frequently found polymer type was polyethylene (>50%), and white color was dominant. The average concentration of bisphenol A (BPA), benzophenone (BP) and diethyl-hydrogen phthalate (DHEP) in leachate was 158 ± 84.4, 0.75 ± 0.16 and 170 ± 85.8 μg/L respectively. Furthermore, BP and DHEP in leachate sediment was 100 ± 68.3 and 1034 ± 455 μg/kg respectively. As landfill leachate is directly discharged into nearby surface and groundwater bodies that serve as sources of drinking water, the study highlights the potential concerns of microplastic and plasticizer exposure to the surrounding Sri Lankan community through consumption of contaminated drinking water. Therefore, there is a timely need of develop the effective waste management and pollution control measures to minimize the possible threats to both the environment and human health.

Clothing Textiles as Carriers of Biological Ice Nucleation Active Particles.

Microplastics have littered the globe, with synthetic fibers being the largest source of atmospheric microplastics. Many atmospheric particles can act as ice nucleators, thereby affecting the microphysical and radiative properties of clouds and, hence, the radiative balance of the Earth. The present study focused on the ice-nucleating ability of fibers from clothing textiles (CTs), which are commonly shed from the normal wear of apparel items. Results from immersion ice nucleation experiments showed that CTs were effective ice nucleators active from -6 to -12 °C, similar to common biological ice nucleators. However, subsequent lysozyme and hydrogen peroxide digestion stripped the ice nucleation properties of CTs, indicating that ice nucleation was biological in origin. Microscopy confirmed the presence of biofilms (i.e., microbial cells attached to a surface and enclosed in an extracellular polysaccharide matrix) on CTs. If present in sufficient quantities in the atmosphere, biological particles (biofilms) attached to fibrous materials could contribute significantly to atmospheric ice nucleation.

A greener, rapid and accurate microwave-assisted hydrogen peroxide digestion method for ICP-OES determination of heavy metals in pet food samples

Microwave-assisted hydrogen peroxide digestion (MW-AHPD) method for determination of Cd, As, Pb, Sn, and Cr in South African pet food samples by inductively coupled plasma-optical emission spectroscopic (ICP-OES) is reported. Multivariate tools and wheat flour certified reference material (FAP80467) assessed limiting factors and reproducibility of the methods respectively. The resulted optimum conditions were: 200 °C, 40 mins, 0.5 g, and 5 mol/L for temperature, time, sample mass and H2O2 concentration, respectively. The method demonstrated excellent accuracy (96–98%), reproducibility (≤ 2.1%) and high detection limits (0.0675–0.3765 µg/g). Then, real pet food samples made from maize, rice, vegetables, fish, and wheat were digested and concentration levels of Cd, Pb, As, Cr and Sn ranged between 11.2 and 22.6, 6.4–11.9, 3.44–13.4, 0.44–2.98 and 0.18–0.98 µg/g, respectively. The three metal ions were above the minimum tolerable limits (Cd: 10 µg/g, Pb:10 µg/g, As: 12.5 µg/g) for some of the fish and wheat based pet food according to the South African regulatory standard. Furthermore, using the AGREEPrep metric tool the method was assessed and had a score of 0.76, confirming its greenness. These findings present MW-AHPD method as an alternative for determination of heavy metals in pet food by ICP-OES.

Occurrence of microplastics in fish gastrointestinal tracts belongs to different feeding habits from the Bangladesh coast of the Bay of Bengal.

The Bay of Bengal (BoB) is home to a range of commercially important species with different food habits and feeding features. Microplastic (MP) contamination in the fish of BoB, like in many other marine environments, is a significant environmental concern. The study aimed to investigate the presence of microplastics (MPs) in the gastrointestinal tracts (GITs) of selected commercial marine fishes from the Bangladesh coast of the BoB. Six fish species (Escualosa thoracata, Tenualosa ilisha, Johnius belangerii, Trichiurus lepturus, Planiliza parsia, and Mystus gulio) were investigated (n = 120) following hydrogen peroxide digestion, and floatation (saline solution) protocols. After analyses, a total number of 696 MPs (dimension 0.3 to 5 mm) were identified. Moreover, the highest occurrence of MPs in fish GITs was found in planktivorous fish (average of 7.7 items/individual), followed by omnivorous (average of 5.2 items/individual), and carnivorous fish (average of 4.6 items/individual) (p < 0.001). However, planktivorous E. thoracata showed the highest number of MPs per g of GIT (average of 30.99 items/g GIT), whereas T. ilisha showed the lowest count (average of 0.77 items/g GIT). Different types of MPs (fibers (19 to 76%), fragments (6 to 61%), films (8 to 35%), microbeads (0 to 5%), and foams (0 to 2%)) were also observed. In terms of the color of MPs, the transparent, black, green, and blue types were the most common. Polymers were found as polyethylene (35 to 43%), polyethylene terephthalate (28 to 35%), polyamide (20 to 31%), and polystyrene (0 to 7%). The study provides a significant incidence of MPs in fish from the Bangladesh part of the BoB, which is very concerning. Therefore, long-term research is indispensable to ascertain the variables affecting the presence of MPs in fish, their origins, and their potential effects on the BoB fisheries. Stringent policies on plastic use and disposal should be strongly urged in this coastal region.

Microplastics and heavy metals in freshwater fish species in the southwestern region of Bangladesh: An emerging concern for public health

Microplastics (MPs) pollution and its associated toxicity raising concerns among scientists as a result of their toxicological impacts on human health and the ecosystem. This study aims to investigate the microplastics and heavy metals (HMs) contamination in seventeen freshwater fish species collected from the Southwestern region of Bangladesh. Microplastics extracted from these species using the hydrogen peroxide digestion method and characterized by Attenuated Total Reflection- Fourier Transform Infrared Spectroscopy (ATR-FTIR). Atomic Absorption Spectrometry (AAS) was used to determine the concentration of HMs in different species for evaluating human health risks. A total of 142 microplastic particles were extracted with an average concentration of 1.13 ± 0.84 items per individual of fish, where the highest microplastics were found in C. punctata (3.43 ± 3.15 items) and lowest in A. mola (0.14 ± 0.38 items). Identified microplastics were dominated by < 1 mm size (87.3%), black color (60.6%), and fiber shape (94.4%). Polyethylene (73.08%), polypropylene (21.15%), and polystyrene (5.77%) were the most prevalent among the identified microplastic polymers. A positive correlation was found between microplastic numbers and fish weight and length. Low to moderate human health risks were associated with microplastics. The concentration (mg/kg) of heavy metals in studied fish samples was Cr (0.47–2.89; 0.79 ± 0.56) > Cu (0.01–1.14; 0.50 ± 0.44) > Pb (0.04–0.58; 0.22 ± 0.12) > Cd (0.00–0.11; 0.03 ± 0.03), respectively. Heavy metals-based human health risk assessment results show that there are no major non-carcinogenic health risks (THI<1), while higher carcinogenic risks are present for consumers.

Microwave-assisted hydrogen peroxide digestion followed by ICP-OES for determination of metals in selected fuel oils

This work describes a greener and cost-effective microwave-assisted hydrogen peroxide digestion (MA-HPD) with the addition of 1 mL of HNO3 (70% v/v) to enhance extraction of selected metals (Al, Ba, Cd, Co, Cr, Cu, Mg, Na, Ni, Pb, Sb, Ti and V) in crude-oil, diesel, gasoline and kerosene samples prior to inductively coupled plasma-optical emission spectroscopic (ICP-OES) analysis. The most influential parameters of the MA-HPD method were investigated by using multivariate optimization tools (two-level full factorial and central composite designs) and fuel oil certified reference material (NIST1634c). The optimum conditions were observed to be 245 ℃ microwave temperature, 25 min digestion time, 0.1 g sample mass and 5 M H2O2 were the optimum digestion conditions with accepted accuracy (104.8–117.7%) and precision (≤ 4.1%). In overall, the metals that reported high concentrations in the crude oil, diesel, gasoline, and kerosene samples were Na (51.94–58.86 mg/kg) and Mg (36.08–47.4 mg/kg), while Cu was the lowest (0.55–2.89 mg/kg). When comparing the obtained concentration levels with other literature reports, a conclusion can be drawn that South Africa is importing oils of reasonable quality.

Quantitative analysis of nanoplastics in environmental and potable waters by pyrolysis-gas chromatography–mass spectrometry

Nanoplastics are emerging environmental contaminants, but their presence in environmental and potable water remains largely understudied due to the absence of quantitative analytical methods. In this study, we developed and validated a pretreatment method that combines hydrogen peroxide digestion and Amicon® Stirred Cell ultrafiltration (at 100 kDa, approximately 10 nm) with subsequent detection by pyrolysis gas chromatography–mass spectrometry (Pyr-GC/MS). This method allows for the simultaneous identification and quantification of nine selected nanoplastic types, including poly(ethylene terephthalate) (PET), polyethylene (PE), polycarbonate (PC), polypropylene (PP), poly(methyl methacrylate) (PMMA), polystyrene (PS), polyvinylchloride (PVC), nylon 6, and nylon 66, in environmental and potable water samples based on polymer-specific mass concentration. Limits of quantification ranged from 0.01 to 0.44 µg/L, demonstrating the method’s ability to quantitatively detect nanoplastics in environmental and potable water samples. Most of the selected nanoplastics were detected at concentrations of between 0.04 and 1.17 µg/L, except for PC, which was consistently below the limit of detection (<0.44 µg/L). The prevalent polymer components in the samples were PE (0.10 – 1.17 µg/L), PET (0.06 – 0.91 µg/L), PP (0.04 – 0.79 µg/L), and PS (0.06 – 0.53 µg/L) nanoplastics. The presented analytical method offers an accurate means to identify, quantify, and monitor nanoplastics in complex environmental and potable water samples. It fills gaps in our understanding of nanoplastic pollution levels, providing a valuable methodology and crucial reference data for future studies.

Fast Forward: Optimized Sample Preparation and Fluorescent Staining for Microplastic Detection

The fast, affordable, and standardized detection of microplastics (MP) remains one of the biggest challenges in MP research. Comparable data are essential for appropriate risk assessments and the implementation of laws and limit values. The fluorescent staining of MP in environmental samples is a possible solution to this problem. This study investigates the optimization of a sample preparation process (hydrogen peroxide digestion) and the staining process (temperature, concentration, time, surfactants as staining aids) for using a specifically developed fluorescent dye for MP detection. The optimization is performed by comparing the sample preparation process and staining of MP from different polymers and natural particles. Further, the suitability of the optimized process for the detection of fluoropolymers and tire abrasion was tested. The results show that the optimized method (increased temperature and optimized stain concentration) can detect microplastics reliably with a total sample preparation and measurement time of 2.5–3 h per sample, reaching recovery rates of 93.3% (polypropylene) to 101.7% (polyester). Moreover, two of the three tested fluoropolymers could be detected reliably. Tire abrasion could not be detected with the here presented method, as the black color leads to strong quenching. A long-term study measuring the MP pollution in the effluent of a municipal wastewater treatment plant compared the optimized and original processes and confirmed the stability of the improved method for routine measurements and contamination control.

Identification, Abundance, and Distribution of Microplastics in Surface Water Collected from Luruaco Lake, Low Basin Magdalena River, Colombia

There are few studies on microplastic (MP) contamination in Colombia, and little is known about its impacts on continental aquatic ecosystems. This study evaluated, for the first time, the identification, abundance, and distribution of MP particles in the surface water of Luruaco Lake, in the low basin of the Magdalena River, Colombia, included in national programs in marine sciences and hydrobiological resources. Six stations and four samplings were established in the dry and rainy seasons. A total of 72 water samples were collected for microplastic extraction using hydrogen peroxide (H2O2) digestion, density separation with sodium chloride solution (NaCl), and filtration. The abundance of MPs ranged from 0 to 3.83 MPs·L−1, with an average of 1.90 MPs·L−1 in the rainy season and 0.25 MPs·L−1 in the dry season. According to the calculated coefficient of microplastics impact, the contamination in the surface water of Luruaco Lake is “maximum” to “extreme” for fibers with an average length of 2.05 mm and “minimum” to “average” for fragments that are 0.35 mm in size on average. Polyester (PES, 57.9%), polystyrene (PS, 47.0%), and polyethylene terephthalate (PET, 35.3%) polymers were more abundant in surface water. The temporal variation of the MPs indicates contamination related to the discharges of the tributary streams to the lake in the rainy season.

Identification and Quantification of Nanoplastics in Surface Water and Groundwater by Pyrolysis Gas Chromatography-Mass Spectrometry.

Nanoplastics (NPs) are currently considered an environmental pollutant of concern, but the actual extent of NP pollution in environmental water bodies remains unclear and there is not enough quantitative data to conduct proper risk assessments. In this study, a pretreatment method combining ultrafiltration (UF, 100 kDa) with hydrogen peroxide digestion and subsequent detection with pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) was developed and used to identify and quantify six selected NPs in surface water (SW) and groundwater (GW), including poly(vinylchloride) (PVC), poly(methyl methacrylate) (PMMA), polypropylene (PP), polystyrene (PS), polyethylene (PE), and poly(ethylene terephthalate) (PET). The results show that the proposed method could detect NPs in environmental water samples. Nearly all selected NPs could be detected in the surface water at all locations, while PVC, PMMA, PS, and PET NPs were frequently below the detection limit in the groundwater. PP (32.9-69.9%) and PE (21.3-44.3%) NPs were the dominant components in both surface water and groundwater, although there were significant differences in the pollution levels attributed to the filtration efficiency of riverbank, with total mass concentrations of 0.283-0.793 μg/L (SW) and 0.021-0.203 μg/L (GW). Overall, this study quantified the NPs in complex aquatic environments for the first time, filling in gaps in our knowledge about NP pollution levels and providing a useful methodology and important reference data for future research.

Unprecedented marine microplastic contamination from the X-Press Pearl container vessel disaster

The objectives of the research was to assess the coastal pollution by plastic nurdles, pyrolitic debris, associated potential toxic elements (PTEs) concentrations and mitigatory efforts by the worst ever maritime accident of a chemical and plastic boarded container vessel; MV X-Press Pearl. Field sampling was carried out three times during May, June, and September 2021 at Sarakkuwa, Sri Lanka. Pellet pollution index (PPI) was determined to compare the degree of plastics pollution. Density separation (NaCl) followed by wet peroxide digestion for plastic separation and characterized by Fourier transform infrared spectroscopic, thermo gravimetric analysis and differential scanning calorimetric analysis. Sand and plastics samples were digested and analyzed for PTEs (Li, Mo, Cr, Pb, and Cu), are suspect to mix during disaster. Identified debris were mostly confirmed as low-density polyethylene, epoxy resins, olefin copolymers, aromatic polyamides, natural rubber, and polyethylene terephthalate. Sulfur contamination and physical erosion were observed in nurdles received in June and September. Calculated PPIs were ‘high’ for Sarakkuwa beach even in September with a very high pellet pollution degree (10.24 pellets per m2) compared to the control obtained from the same site in 2020 (1.6 pellets per m2). Input sand for the blue treatment facility was found as the extremely contaminated with Mo and Li with 239.71 and 1.69 mg/kg respectively other than microplastics. Blue treatment facility seemed effective in physical separation of microplastics from sand, however, it is an exhausting process due to continuous receive of microplastics from the waves and excavation of sea shore.

Soil Invertebrates Generate Microplastics From Polystyrene Foam Debris

To fully understand microplastics' impact on soil ecosystems, one must recognize soil organisms as not just passively enduring their negative effects, but potentially contributing to microplastics' formation, distribution, and dynamics in soil. We investigated the ability of four soil invertebrates, the cricket Gryllodes sigillatus Walker (Orthoptera: Gryllidae), the isopod Oniscus asellus L. (Isopoda: Oniscidae), larvae of the beetle Zophobas morio Fabricius (Coleoptera: Tenebrionidae), and the snail Cornu aspersum Müller (Stylommatophora: Helicidae) to fragment macroscopic pieces of weathered or pristine polystyrene (PS) foam. We placed invertebrates into arenas with single PS foam pieces for 24 h, then collected and assessed the microplastic content of each invertebrate's fecal material, its cadaver, and the sand substrate of its arena via hydrogen peroxide digestion, filtration, and fluorescent staining. All taxa excreted PS particles, though snails only to a tiny extent. Beetle larvae produced significantly more microplastics than snails, and crickets and isopods fragmented the weathered PS foam pieces more than the pristine pieces, which they left untouched. A follow-up experiment with pristine PS foam assessed the effect of different treatments mimicking exposure to the elements on fragmentation by isopods. PS foam pieces soaked in a soil suspension were significantly more fragmented than untreated pieces or pieces exposed to UV light alone. These findings indicate that soil invertebrates may represent a source of microplastics to the environment in places polluted with PS foam trash, and that the condition of macroplastic debris likely affects its palatability to these organisms.

Ice Nucleating Particle Connections to Regional Argentinian Land Surface Emissions and Weather During the Cloud, Aerosol, and Complex Terrain Interactions Experiment

AbstractHere, we present a multi‐season study of ice‐nucleating particles (INPs) active via the immersion freezing mechanism, which took place in north‐central Argentina, a worldwide hotspot for mesoscale convective storms. INPs were measured untreated, after heating to 95°C, and after hydrogen peroxide digestion. No seasonal cycle of INP concentrations was observed. Heat labile INPs, which we define as “biological” herein, dominated the population active at −5 to −20°C, while non‐heat‐labile organic INPs (decomposed by peroxide) dominated at lower temperatures, from −20 to −28°C. Inorganic INPs (remaining after peroxide digestion), were minor contributors to the overall INP activity. Biological INP concentration active around −12°C peaked during rain events and under high relative humidity, reflecting emission mechanisms independent of the background aerosol concentration. The ratio of non‐heat‐labile organic and inorganic INPs was generally constant, suggesting they originated from the same source, presumably from regional arable topsoil based on air mass histories. Single particle mass spectrometry showed that soil particles aerosolized from a regionally common agricultural topsoil contained known mineral INP sources (K‐feldspar and illite) as well as a significant organic component. The INP activity observed in this study correlates well with agricultural soil INP activities from this and other regions of the world, suggesting that the observed INP spectra might be typical of many arable landscapes. These results demonstrate the strong influence of regional continental landscapes, emitting INPs of types that are not yet well represented in global models.

Microplastics in agricultural soils, wastewater effluents and sewage sludge in Mauritius

The rapid and silent emergence of microplastics (MPs) in the environment has recently become a global problem with more and more studies are showing the harmful effects of MPs on different ecosystems. The aim of this study was to investigate the presence of MPs in agricultural soils, wastewater effluents and sewage sludge in Mauritius. The soil samples were collected randomly from three different agricultural lands which have been used for conventional agriculture for more than 25 years. Wastewater effluents and sewage sludge were collected once, using the grab sampling method, from three main operating wastewater treatment plants (WWTP) across the island and were analysed in triplicate. MPs were extracted using the flotation technique, followed by hydrogen peroxide digestion. The abundance of MPs was found to be 320.0 ± 112.2 and 420.0 ± 244.0 particles.kg-1 in shallow and deep soils, respectively, out of which 42.4% and 95.8% were less than 1 mm in size, respectively. Site 3 had the highest abundance of MPs due to cumulated plastic debris dumped on the field. In addition, the average MPs concentration in sewage sludge and in wastewater effluents were 14,750 ± 8612.9 particles.kg-1 and 276.3 ± 137.3 particles.L-1, respectively, whereby 90% of the MPs were less than 0.5 mm in size. WWTP 1 had the largest share of MPs in both sewage sludge and wastewater effluents. The attenuated total reflection Fourier transform infrared spectroscopy revealed that polypropylene (fibres, fragments, and flakes) was in abundance in agricultural soil samples by 56.26%, while in WWTP polyamide (fibres) was predominant by 88.85%. The findings of this preliminary study confirmed the presence of MPs in Mauritian lands, wastewater effluents and sewage sludge and therefore provide salient data to advocate for subsequent research on MPs.

Evaluating the potential for Haloarchaea to serve as ice nucleating particles

Abstract. Aerosols play a crucial role in cloud formation. Biologically derived materials from bacteria, fungi, pollen, lichen, viruses, algae, and diatoms can serve as ice nucleating particles (INPs), some of which initiate glaciation in clouds at relatively warm freezing temperatures. However, determining the magnitude of the interactions between clouds and biologically derived INPs remains a significant challenge due to the diversity and complexity of bioaerosols and limited observations of such aerosols facilitating cloud ice formation. Additionally, microorganisms from the domain Archaea have, to date, not been evaluated as INPs. Here, we present the first results reporting the ice nucleation activity of four species in the class Haloarchaea. Intact cells of Halococcus morrhuae and Haloferax sulfurifontis demonstrated the ability to induce immersion freezing at temperatures up to −18 ∘C, while lysed cells of Haloquadratum walsbyi and Natronomonas pharaonis were unable to serve as immersion INPs. Exposure to heat and peroxide digestion indicated that the INPs of intact cells were driven by organic (H. morrhuae and H. sulfurifontis) and possibly also heat labile materials (H. sulfurifontis only). While halophiles are prominent in hypersaline environments such as the Great Salt Lake and the Dead Sea, other members of the Archaea, such as methanogens and thermophiles, are prevalent in anoxic systems in seawater, sea ice, marine sediments, glacial ice, permafrost, and other cold niches. Archaeal extremophiles are both diverse and highly abundant. Thus, it is important to assess their ability to serve as INPs as it may lead to an improved understanding of biological impacts on clouds.

The measurement and full statistical analysis including Bayesian methods of the aluminium content of infant vaccines

BackgroundAluminium salts are the most common adjuvants in infant vaccines. The aluminium content of a vaccine is provided by the manufacturer and is indicated on the patient information leaflet. There is no independent verification, for example by the European Medicines Agency, of the aluminium content of infant vaccines. MethodsWe have measured the aluminium content of thirteen infant vaccines using microwave-assisted acid and peroxide digestion followed by transversely heated graphite furnace atomic absorption spectrometry. Our data are compared with manufacturer’s data using full statistical analyses including Bayesian methods. ResultsWe found that only three vaccines contained the amount of aluminium indicated by the manufacturer. Six vaccines contained a statistically significant (P < 0.05) greater quantity while four vaccines contained a statistically significant (P < 0.05) lower quantity. The range of content for any single vaccine varied considerably, for example, from 0.172 to 0.602 mg/vaccine for Havrix. ConclusionsThe data have raised specific questions about the significance of the aluminium content of vaccines and identified areas of extremely limited information. Since aluminium is a known toxin in humans and specifically a neurotoxin, its content in vaccines should be accurate and independently monitored to ensure both efficacy and safety.

Microwave-assisted single-step extraction method for determination of heavy metals in saline soil and compare with conventional sequential extraction method

The present research assesses the chemical fractionation of cadmium (Cd), chromium (Cr), and lead (Pb) detected in saline soil samples of Hyderabad Pakistan. Based on the reagents used in the BCR three-step conventional sequential extraction (CSE) for partitioning Cd, Cr, and Pb in saline soil samples, a Microwave induced single-step extraction (MSE) method was developed. The validity of the method was confirmed using certified reference material (CRM) BCR-483 and the standard method of addition (recoveries 96–102%). The data provided by the BCR- CSE method for Cd, Cr and Pb partition were compatible with MSE using the same operating conditions applied and checked in BCR fraction by the Certified Reference Material (CRM) BCR-483. Using compromised sonication and microwave conditions steps 1–3 of the sequential extraction (excluding hydrogen peroxide digestion in step 3) could be accomplished with ultrasonic bath between 15 and 30 min, whereas 60–120 s needed for MSE. The total concentrations of Cd, Cr, and Pb extractable metals produced by three separate extractions ranged 1.02–3.30, 5.02–9.95 and 3.97–8.01 μgg−1, respectively. The accuracy of the proposed BCR single extraction methods (expressed as RSD %) for all metals was found within the range of (4.99–8.61%).

Accumulation of airborne microplastics in lichens from a landfill dumping site (Italy)

The aim of this study was to assess if lichens (Flavoparmelia caperata) surrounding a landfill dumping site in Italy accumulated higher amounts of microplastics compared with lichens at more distant sites. Lichen samples were collected at three sites along a transect from the landfill: close (directly facing the landfill), intermediate (200 m), and remote (1500 m). Anthropogenic microparticles (fibres and fragments) were determined visually after wet peroxide digestion of the samples, and microplastics were identified based on a hot needle test; the type of plastic was identified by micro-Raman analysis. The results showed that lichens collected in the vicinity of the landfill accumulated the highest number of anthropogenic microfibres and fragments (147 mp/g dw), and consequently microplastics (79 mp/g dw), suggesting that the impact of landfill emissions is spatially limited. The proportion of fibres and fragments identified as microplastics was 40% across all sites and the most abundant polymer type was polyester or polyethylene terephthalate (68%). These results clearly indicated that lichens can effectively be used to monitor the deposition of microplastics.