Sensitive visual detection of norfloxacin in water by smartphone assisted colorimetric method based on peroxidase-like active cobalt-doped Fe3O4 nanozyme.

Norfloxacin is widely used owing to its strong bactericidal effect on Gram-negative bacteria. However, the residual norfloxacin in the environment can be biomagnified via food chain and may damage the human liver and delay the bone development of minors. Present work described a reliable and sensitive smartphone colorimetric sensing system based on cobalt-doped Fe3O4 magnetic nanoparticles (Co-Fe3O4 MNPs) for the visual detection of norfloxacin. Compared with Fe3O4, Co-Fe3O4 MNPs earned more remarkably peroxidase-like activity and TMB (colorless) was rapidly oxidized to oxTMB (blue) with the presence of H2O2. Interestingly, the addition of low concentration of norfloxacin can accelerate the color reaction process of TMB, and blue deepening of the solution can be observed with the naked eye. However, after adding high concentration of norfloxacin, the activity of nanozyme was inhibited, resulting in the gradual fading of the solution. Based on this principle, a colorimetric sensor integrated with smartphone RGB mode was established. The visual sensor exhibited good linearity for norfloxacin monitoring in the range of 0.13-2.51 µmol/L and 17.5-100 µmol/L. The limit of visual detection was 0.08 µmol/L. In the actual water sample analysis, the spiked recoveries of norfloxacin were over the range of 95.7%-104.7 %. These results demonstrated that the visual sensor was a convenient and fast method for the efficient and accurate detection of norfloxacin in water, which may have broad application prospect.

Assessment of an eco-efficient process for the optimization of metal recovery in lithium cobalt oxide and lithium nickel manganese cobalt oxide batteries.

The expansion of technology motivates the increase of global demands for critical minerals. In this context, the exploration of secondary sources of these components is expanding. End-of-life batteries can be seen as potential sources of lithium, cobalt, nickel and manganese for electric vehicles or diverse applications in electronic equipments. This paper provides a comprehensive evaluation of the recovery of metals from waste batteries with diverse chemistry composition. Lithium cobalt oxide (LCO) and lithium nickel cobalt manganese oxide (NMC) batteries were co-treated with polyvinyl chloride (PVC) channels under supercritical water, varying reaction temperature (400-600 °C) and PVC/Battery composition (0-3 m/m) in a tubular continuous reactor. Results show high recovery rates for all metals, with up to 90% percentage recovery of lithium and cobalt in all cases. Temperature and feed composition were identified as determining factors for the recovery of lithium from LCO batteries. In the case of cobalt, temperature was identified as the most important factor that affects its recovery. The selected optimal conditions for cobalt recovery in the solid products of reactions were identified for batteries LCO and NMC: temperature of 600 °C and PVC/Battery ratio of 3.0 and temperature of 500 °C and PVC/Battery ratio of 1.5, respectively. Environmental impacts, primarily Global Warming Potential (GWP), were minimal, with 4.71·10-5 kg CO2 eq., indicating the benefits of the process as an eco-efficient and promising route for the recycling of valuable metals.

High performance enrichment and analysis of fluoroquinolones residues in environmental water using cobalt ion mediated paper-based molecularly imprinted polymer chips.

BACKGROUND: Fluoroquinolones (FQs) are widely used for their excellent antimicrobial properties, yet their release into aquatic environments pose risks to ecosystems and public health. The accurate monitoring and analysis of FQs present challenges due to their low concentrations and the complex matrices found in actual environmental samples. To address the need for auto-pretreatment and on-line instrumental analysis, developing new microextraction materials and protocols is crucial. Such advancements will provide better analytical assurance for the effective extraction and determination of FQs at trace levels, which is of great significance to environmental protection and human health. RESULTS: In this work, we presented a Co2+ mediated paper-based molecularly imprinted polymer chip (CMC@Co-MIP), combined with UPLC analysis, to develop an effective analytical method for identifying and quantifying trace amounts of ciprofloxacin (CIP) and enrofloxacin (ENR) in water samples. Notably, the addition of Co2+ in CMC@Co-MIP helped to capture the template molecule CIP through coordination before imprinting, which significantly improved the ordering of the imprinted cavities. CMC@Co-MIP exhibited a maximum adsorption capacity up to 500.20 mg g-1 with an imprinting factor of 4.12, surpassing previous reports by a significant margin. Furthermore, the enrichment mechanism was extensively analyzed by various characterization techniques. The developed method showed excellent repeatability and reproducibility (RSD < 13.0 %) with detection limits ranging from 0.15 to 0.21 µg L-1 and recoveries ranging from 64.9 % to 102.3 % in real spiked water samples. SIGNIFICANCE: We developed a novel microextraction paper-based chip based on Co2+ mediation, which effectively improved the selectivity and convenience of extracting FQs. This breakthrough allowed the chip to have a high enrichment efficiency as well as provide a robust on-line instrumental program. It also confirms that the imprinting scheme based on metal ion coordination is a high-performance strategy.

Fractionation, spatial distribution, ecological and health risk assessment of cobalt and nickel in surface sediment of a bay along the southeast coast of China.

The fractionation and distribution of two potentially toxic elements (Co and Ni) were investigated in surface sediments to explore the pollution in Xiamen Bay, a special zone experiencing rapid economic growth and enormous environmental pressure. Relatively high concentrations were observed in nearshore areas with frequent human activities. The dominant fractions for Co and Ni were found to be residual, followed by exchangeable phase. Spatial differences in mobility and bioavailability inferred from chemical fractionations were more pronounced for Ni. Multiple evaluation methods including geo-accumulation index, risk assessment code, modified potential ecological risk index, etc., consistently indicated that pollution levels and ecological risks in the entire bay were generally classified as medium-low. However, non-carcinogenic risks of Co for children and carcinogenic risks of Ni for adults exceeded safety thresholds. Terrestrial weathering processes and industrial activities primarily contributed to the presence of these elements, while their distributions were mainly influenced by organic matter.

Including the rare cubane cluster cobalt coordination polymer as the fluorescent sensing material for selectively and sensitively detecting the nitrofurantoin antibiotic.

More and more attention has been paid to food safety. Due to the overuse and misuse of antibiotics, the problem of antibiotic residues in animal food is one of the important challenges to ensure food safety. The development of a feasible strategy to detect antibiotic residues in animal food has become desirable. In this paper, we creatively synthesize a water-stable fluorescence sensing material, namely, Co(Ⅱ)-Coordination polymer [Co2(CA) (L)0.5 (H2O)3] n (L = 1,4-bis(imidazole-1-ylmethyl) benzene, CA= Citric acid). The single crystal X-ray diffraction shows that it crystallizes in tetragonal space group I-4. It is worth mentioning that there exists the rare Co4(µ3-O)4 cubane cluster structure and Co8 cluster units. Those adjacent Co8 cluster units are connected into an infinite two-dimensional net structure by four flexible bridged L ligands. Finally, the Co(Ⅱ)-Coordination polymer (CP) further develops into the three-dimensional supramolecular structure via the hydrogen bonds of O-H⋯O and C-H⋯O. It could selectively detect the antibiotic-nitrofurantoin (NFT) residue by way of fluorescence quenching, Co-CP for the detection of NFT shows broad linearity from 0 to 200 µM, with a detection limit of 0.13 µM and strong anti-interference ability. It is used to detect the NFT residual of tap water and milk with a spiked recovery of 86.35-112.47 %.

Comparison of the Cobalt Content in Needles Stainless Steel.

Cobalt (Co) alloys are used extensively in a wide range of medical devices due to their biocompatibility, durability, and properties. In 2017 the European Chemical Agency (ECHA) proposed to classify Co metal as a category 1B carcinogen (i.e. presumed to have carcinogenic potential for humans), as a reproductive hazard category 1B (i.e. presumed human reproductive toxicant) and as a category 2 mutagen. Even more, the European Medical Device Regulation (MDR) requires that medical devices contain > 0,1 w/w of substances that are category 1 A and 1B (CMR). As far as the European Medical Device Regulation, it is not specified if the Co content and concentration had to be determined/measured on the entire product or only on the product components. The object of this work is the comparison of Co profile in three different suppliers of stainless-steel needles as is and after being processed (i.e. sterilized) and then provide the proper interpretation and application of MDR requirements. The study and the extractable profile demonstrate the low cobalt content on needles and on a total syringe, thus suggesting to consider the Co content only on the syringe component.

Efficient mixed-potential acetone sensor with yttria-stabilized zirconia and porous Co3O4 nanofoam sensing electrode for hazardous gas monitoring and breath analysis.

For hazardous gas monitoring and non-invasive diagnosis of diabetes using breath analysis, porous foams assembled by Co3O4 nanoparticles were designed as sensing electrode materials to fabricate efficient yttria-stabilized zirconia (YSZ)-based acetone sensors. The sensitivity of the sensors was improved by varying the sintering temperature to regulate the morphology. Compared to other materials sintered at different temperatures, the porous Co3O4 nanofoams sintered at 800 °C exhibited the highest electrochemical catalytic activity during the electrochemical test. The response of the corresponding Co3O4-based sensor to 10 ppm acetone was -77.2 mV and it exhibited fast response and recovery times. Moreover, the fabricated sensor achieved a low detection limit of 0.05 ppm and a high sensitivity of -56 mV/decade in the acetone concentration range of 1-20 ppm. The sensor also exhibited excellent repeatability, acceptable selectivity, good O2/humidity resistance, and long-term stability during continuous measurements for over 30 days. Moreover, the fabricated sensor was used to determine the acetone concentration in the exhaled breaths of patients with diabetic ketosis. The results indicated that it could distinguish between healthy individuals and patients with diabetic ketosis, thereby proving its abilities to diagnose and monitor diabetic ketosis. Based on its excellent sensitivity and exhaled breath measurement results, the developed sensor has broad application prospects.

A dual-modality sensing probe of fluorescent and colorimetric for detection of cobalt ion based on silver nanoparticles functionalized rhodamine 6G derivatives.

The combination of fluorescent probe and colorimetric technique has become one of the most powerful analytical methods due to the advantages of visualization, minimal measurement errors and high sensitivity. Hence, a novel dual-modality sensing probe with both colorimetric and fluorescent capabilities was developed for detecting cobalt ions (Co2+) based on homocysteine mediated silver nanoparticles and rhodamine 6G derivatives probe (AgNPs-Hcy-Rh6G2). The fluorescence of the AgNPs-Hcy-Rh6G2 probe turned on due to the opening of the Rh6G2 spirolactam ring in the presence of Co2+ by a catalytic hydrolysis. The fluorescent intensity of probe is proportional to Co2+ concentration in the range of 0.10-50 µM with a detection limit of 0.05 µM (S/N = 3). More fascinatingly, the color of AgNPs-Hcy-Rh6G2 probe changed from colorless to pink with increasing Co2+ concentration, which allowing colorimetric determination of Co2+. The absorbance of AgNPs-Hcy-Rh6G2 probe is proportional to Co2+ concentration in the range from 0.10 to 25 µM with a detection limit of 0.04 µM (S/N = 3). This colorimetric and fluorescent dual-modal method exhibited good selectivity, and reproducibility and stability, holding great potential for real samples analysis in environmental and drug field.

Exploring the diverse performance of nickel and cobalt spinel ferrite nanoparticles in hazardous pollutant removal and gas sensing performance.

A simple sol-gel combustion process was employed for the creation of MFe2O4 (M=Ni, Co) nanoparticles. The synthesized nanoparticles, acting as both photocatalysts and gas sensors, were analyzed using various analytical techniques. MFe2O4 (M=Ni, Co) material improved the degradation of methylene blue (MB) under UV-light irradiation, serving as an enhanced electron transport medium. UV-vis studies demonstrated that NiFe2O4 achieved a 60% degradation, while CoFe2O4 nanostructure exhibited a 76% degradation efficacy in the MB dye removal process. Furthermore, MFe2O4 (M=Ni, Co) demonstrated chemosensitive-type sensor capabilities at ambient temperature. The sensor response and recovery times for CoFe2O4 at a concentration of 100 ppm were 15 and 20, respectively. Overall, the synthesis of MFe2O4 (M=Ni, Co) holds the potential to significantly improve the photocatalytic and gas sensing properties, particularly enhancing the performance of CoFe2O4. The observed enhancements make honey MFe2O4 (M=Ni, Co) a preferable choice for environmental remediation applications.

Mitigation of drought stress in chili plants (Capsicum annuum L.) using mango fruit waste biochar, fulvic acid and cobalt.

Drought stress can have negative impacts on crop productivity. It triggers the accumulation of reactive oxygen species, which causes oxidative stress. Limited water and nutrient uptake under drought stress also decreases plant growth. Using cobalt and fulvic acid with biochar in such scenarios can effectively promote plant growth. Cobalt (Co) is a component of various enzymes and co-enzymes. It can increase the concentration of flavonoids, total phenols, antioxidant enzymes (peroxidase, catalase, and polyphenol oxidase) and proline. Fulvic acid (FA), a constituent of soil organic matter, increases the accessibility of nutrients to plants. Biochar (BC) can enhance soil moisture retention, nutrient uptake, and plant productivity during drought stress. That's why the current study explored the influence of Co, FA and BC on chili plants under drought stress. This study involved 8 treatments, i.e., control, 4 g/L fulvic acid (4FA), 20 mg/L cobalt sulfate (20CoSO4), 4FA + 20CoSO4, 0.50%MFWBC (0.50 MFWBC), 4FA + 0.50MFWBC, 20CoSO4 + 0.50MFWBC, 4FA + 20CoSO4 + 0.50MFWBC. Results showed that 4 g/L FA + 20CoSO4 with 0.50MFWBC caused an increase in chili plant height (23.29%), plant dry weight (28.85%), fruit length (20.17%), fruit girth (21.41%) and fruit yield (25.13%) compared to control. The effectiveness of 4 g/L FA + 20CoSO4 with 0.50MFWBC was also confirmed by a significant increase in total chlorophyll contents, as well as nitrogen (N), phosphorus (P), and potassium (K) in leaves over control. In conclusion4g/L, FA + 20CoSO4 with 0.50MFWBC can potentially improve the growth of chili cultivated in drought stress. It is suggested that 4 g/L FA + 20CoSO4 with 0.50MFWBC be used to alleviate drought stress in chili plants.

Eco-friendly cobalt-doped carbon quantum dots for spectrofluorometric determination of pregabalin in pharmaceutical capsules.

The misuse of pregabalin has become a significant issue over the last decade. Consequently, there is a growing demand for a sensitive and selective method for its determination. In this study, an eco-friendly cobalt-doped carbon quantum dots (CQDs) have been fabricated and applied as nanoprobes for the fluorometric determination of pregabalin. The CQDs were synthesized through mixed doping with non-metallic atoms such as nitrogen and sulfur, and a metal ion, cobaltous ion, via a microwave-assisted method in just 1.5 min. The synthesized Co-NS-CQDs exhibited advantageous characteristics, including rapid response times, compatibility with various pH levels, exceptional detection limits, high sensitivity, and excellent selectivity. The Co-NS-CQDs exhibited a high quantum yield (55 %) relative to NS-CQDs (38 %), with blue emissive light at 438 nm. The assessment of pregabalin was based on its enhancement effect on the native fluorescence intensity of CQDs. The proposed method had a good linearity over the range of 25-250 µg/mL, with a limit of detection of 4.17 µg/mL and a limit of quantitation of 12.63 µg/mL, respectively. The prepared NS-CQDs have been successfully applied for the pregabalin determination in pharmaceutical capsules, with excellent % recovery (98-102 %). The greenness of the developed method has been investigated using different greenness metrics, in comparison with the reported RP HPLC method. The greenness characteristics of the method originated from the synthesis of CQDs, utilizing sustainable, readily available, and cost-effective starting materials.

Dissimilarity of megabenthic community structure between deep-water seamounts with cobalt-rich crusts: Case study in the northwestern Pacific Ocean.

As anthropogenic disturbance on deep-sea seamount ecosystems grows, there is an urgent need for a better understanding of the biodiversity and community structure in benthic ecosystems, which can vary at local and regional scales. A survey of the benthic megafauna on two adjacent deep-water seamounts in the northwestern Pacific Ocean was conducted, which are covered by cobalt-rich crusts, to assess the biodiversity patterns and dissimilarity of assemblage composition. Based on a multidisciplinary dataset generated from video recordings, multibeam bathymetry data, and near-bottom currents, environmental and spatial factors impacting the megabenthic communities were explored. Results showed that these two deep-water seamounts were dominated by hexactinellids, crinoids, and octocorals. The seamounts were able to support diverse and moderately abundant megafauna, with a total of 6436 individuals classified into 94 morphospecies. The survey covered a distance of 52.2 km across a depth range of 1421-3335 m, revealing multiple distinct megabenthic assemblages. The megabenthic communities of the two deep-water seamounts, with comparable environmental conditions, exhibited similarities in overall density, richness, and faunal lists, while dissimilarities in the relative abundance of taxa and assemblage composition. No gradual depth-related change in terms of abundance, richness, or species turnover was observed across the two seamounts, despite the statistical significance of depth in structuring the overall communities. The spatial distribution of megabenthic communities displayed a discontinuous and patchy pattern throughout the two deep-water seamounts. This patchiness was driven by the interactive effects of multiple environmental factors. Near-bottom currents and microhabitat features were the primary drivers influencing their dissimilarities in megabenthic community structure. This case study on the megabenthic community structure of two adjacent seamounts with cobalt-rich crusts can serve as an environmental baseline, providing a reference status for the conservation and management of seamount ecosystems, particularly valuable for areas being considered for deep-sea mining.

Synergistic Manganese Cobalt Phosphide core-shell for the Electrochemical Detection of Methyl Parathion in Food Sample.

The development of a robust electrocatalyst for the electrochemical sensor for hazardous pesticides will reduce its effects on the ecosystem. Herein, we synthesized the robust manganese cobalt phosphide (MnCoP) - Core-shell as an electrochemical sensor for the determination of hazardous pesticide methyl parathion (MP). The MnCoP- Core-shell was prepared with the sustainable self-template route can help with the larger surface area. The Core-shell structure of MnCoP possesses a higher active surface area which increases the electrocatalytic performance and is utilized to improve the electrochemical MP reduction with the synergism of the core and shell structure. Remarkably, it realizes the higher sensitivity (0.014 µA µM-1 cm-2) of MnCoP- Core-shell/GCE achieves towards MP with lower limit of detection (LoD 50 nM) and exceptional recovery rate of MP in vegetable samples are achieved with the differential pulse voltammetry (DPV) technique. The MnCoP- Core-shell electrode reserved their superior electrochemical performances with high reproducibility and repeatability. This prominent activity of the MnCoP core-shell towards the MP in real sample analysis, makes it a promising electrochemical sensor for the detection of MP.

[Determination of 24 elements migration in Yixing clay pottery by inductively coupled plasma mass spectrometry].

OBJECTIVE: To establish an analytical method for determining the migration of 24 elements in Yixing clay pottery in 4% acetic acid simulated solution by inductively coupled plasma mass spectrometry. METHODS: Four types of Yixing clay pottery, including Yixing clay teapot, Yixing clay kettle, Yixing clay pot, and Yixing clay electric stew pot, were immersed in 4% acetic acid as a food simulant for testing. The migration amount of 24 elements in the migration solution was determined using inductively coupled plasma mass spectrometry. RESULTS: Lithium, magnesium, aluminum, iron, and barium elements with a mass concentration of 1000 µg/L; Lead, cadmium, total arsenic, chromium, nickel, copper, vanadium, manganese, antimony, tin, zinc, cobalt, molybdenum, silver, beryllium, thallium, titanium, and strontium elements within 100 µg/L there was a linear relationship within, the r value was between 0.998 739 and 0.999 989. Total mercury at 5.0 µg/L, there was a linear relationship within, the r value of 0.995 056. The detection limit of the elements measured by this method was between 0.5 and 45.0 µg/L, the recovery rate was 80.6%-108.9%, and the relative standard deviation was 1.0%-4.8%(n=6). A total of 32 samples of four types of Yixing clay pottery sold on the market, including teapots, boiling kettles, casseroles, and electric stewing pots, were tested. It was found that the migration of 16 elements, including beryllium, titanium, chromium, nickel, cobalt, zinc, silver, cadmium, antimony, total mercury, thallium, tin, copper, total arsenic, molybdenum, and lead, were lower than the quantitative limit. The element with the highest migration volume teapot was aluminum, magnesium, and barium; The kettle was aluminum and magnesium; Casserole was aluminum, magnesium, and lithium; The electric stew pot was aluminum. CONCLUSION: This method is easy to operate and has high accuracy, providing an effective and feasible detection method for the determination and evaluation of element migration in Yixing clay pottery.

In-situ growth of MOF-derived Co3S4@MoS2 heterostructured electrocatalyst for the detection of furazolidone.

The over-exploitation of antibiotics in food and farming industries ruined the environmental and human health. Consequently, electrochemical sensors offer significant advantages in monitoring these compounds with high accuracy. Herein, MOF-derived hollow Co3S4@MoS2 (CS@MS) heterostructure has been prepared hydrothermally and applied to fabricate an electrochemical sensor to monitor nitrofuran class antibiotic drug. Various spectroscopic methodologies have been employed to elucidate the structural and morphological information. Our prepared electrocatalyst has better electrocatalytic performance than bare and other modified glassy carbon electrodes (GCE). Our CS@MS/GCE sensor exhibited a highly sensitive detection by offering a low limit of detection, good sensitivity, repeatability, reproducibility, and stability results. In addition, our sensor has shown a good selectivity towards the target analyte among other potential interferons. The practical reliability of the sensor was measured by analyzing various real-time environmental and biological samples and obtaining good recovery values. From the results, our fabricated CS@MS could be an active electrocatalyst material for an efficient electrochemical sensing application.

Application of cobalt-cerium-iron ternary layered double hydroxide for extraction of perfluorooctane sulfonate followed by HPLC-MS/MS analysis.

Herein, Ce-doped CoFe layered double hydroxide (LDH), noted as CoCeFe ternary LDH, was prepared using the co-precipitation route. Prosperous synthesis of CoFe LDH and successful partial replacement of iron cations with cerium cations in CoCeFe ternary LDH were confirmed by X-ray diffraction patterns, energy-dispersive X-ray spectroscopy, and elemental dot-mapping images. Nanosheet morphology was recognized for both CoFe LDH and CoCeFe ternary LDH from scanning electron microscopy and transmission electron microscopy micrographs. In the following, a dispersive solid phase extraction (DSPE) method was developed using the synthesized CoCeFe ternary LDH as a sorbent for extracting perfluorooctanesulfonic acid (PFOS) from wastewater samples. For the selective analysis of PFOS, high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS) in multiple reaction monitoring mode was used. Analytical parameters such as the limit of detection equal to 0.02 µg/L, with a linear range of 0.05-300 µg/L, the limit of quantification equal to 0.05 µg/L, and an enrichment factor equal to 23.3 were achieved for PFOS at the optimized condition (sorbent: 5 mg of CoCeFe ternary LDH, eluent type and volume: 150 µL mobile phase, pH: 3, adsorption time: 3 min, and desorption time: 5 min). The developed strategy for the analysis of PFOS was tested in real wastewater samples, including copper mine and petrochemical wastewater. The amount of analytes in real samples was calculated using the standard addition method, and good relative recovery in the range of 86%-105% was obtained. The main novelty of this research is the application of CoCeFe ternary LDH to extract the PFOS from wastewater using the DSPE method for determination by HPLC-MS/MS.

Analyte Extension Method Validation of Elemental Analysis Manual Method 4.7 for Six Additional Elements, Cobalt (Co), Strontium (Sr), Thallium (Tl), Tin (Sn), Uranium (U), and Vanadium (V).

BACKGROUND: An interlaboratory study was conducted at the U.S. Food and Drug Administration's (FDA) Northeast Food and Feed Laboratory (NFFL) and the Center for Food Safety and Applied Nutrition (CFSAN) with the purpose to expand FDA Elemental Analysis Manual (EAM) method 4.7 (Inductively Coupled Plasma-Mass Spectrometric Determination of Arsenic, Cadmium, Chromium, Lead, Mercury, and Other Elements in Food Using Microwave Assisted Digestion) to include new analytes. OBJECTIVE: The goal of the study was to demonstrate the performance of FDA EAM method 4.7 when analyzing new analytes cobalt (Co), strontium (Sr), thallium (Tl), tin (Sn), uranium (U), and vanadium (V). This analyte extension method validation of EAM 4.7 for six additional elements, Co, Sr, Tl, Sn, U, and V, followed all guidelines for a Level 2 or single-laboratory validation and met all acceptance criteria for analyte extensions as per the Guidelines for the Validation of Chemical Methods. METHOD: As per EAM 4.7, this study followed the procedures and used specified equipment operated under recommended conditions. The analyte extension method validation was performed in accordance with protocol and with no deviations. RESULTS: All quality control (QC) requirements for this analyte extension method validation of EAM 4.7 passed as evidenced by the analytical data. The results presented demonstrate accuracy, linearity, and precision by successful analyses of method blanks, matrix spikes, unfortified test samples, and reference materials. The data analyzed met each of the validation requirements for each analyte in all representative matrixes. CONCLUSIONS: The study showed that the new analytes performed satisfactorily using EAM 4.7 for total acidic extractable elemental analysis of food according to FDA's guidelines. HIGHLIGHTS: The method met or exceeded the performance criteria.

Investigation on trommeled legacy waste from full-scale mining of old dumpsites: Suitable for valorization or scientific disposal?

The burgeoning interest in resource recovery from old dumpsites has significantly propelled the adoption of Landfill Mining (LFM) in recent years. This study is centred around evaluating the quality of materials recovered from the full-scale LFM activities at two major dumpsites in India, focusing on the valorization potential of the segregated legacy waste. A detailed analysis was conducted on the segregated waste fractions based on particle size (-30 mm, 30 to 6 mm, and -6 mm, as sourced from the sites), employing both batch and column leaching methods across a range of liquid-to-solid (L/S) ratios (0.1-10.0 L/kg). The findings reveal a pronounced concentration of contaminants within the -6 mm fraction compared to the 30 to 6 mm and -30 mm fractions. Column leaching tests revealed a reduction in contaminant concentration, correlating with incremental changes in L/S ratio. Notably, this trend remained consistent across varying particle sizes and specific type of contaminants assessed. Notably, color intensity of leachate reduced significantly from 720 to 1640 Platinum Cobalt Units (PCU) at an L/S ratio of 0.1 L/kg to a minimal 94-225 PCU at an L/S of 10 L/kg. Dissolved salts emerged as a primary concern, marking them as significant contaminants in both leaching methods. The analysis confirmed that the segregated fractions comply with the USEPA Waste Acceptance Criteria (WAC), permitting their disposal in non-hazardous waste landfills. However, the elevated presence of dissolved salts, exceeding reuse limits by 5-35 times, limits their open or unrestricted reuse. Despite this, isolated reuse aligns with regulations from the Netherlands and Germany, suggesting viable pathways for compliant utilization. Geotechnical assessments indicate the potential for repurposing the -30 mm fraction as alternative earthfill and construction material. While heavy metal leaching does not pose significant concerns, the prevalent unscientific disposal practices near urban settlements highlight potential human health risks. This investigation enriches the understanding of the physicochemical properties, leaching behaviour, and reuse potential of segregated legacy waste, offering crucial insights for civic authorities in determining appropriate reuse and disposal strategies for such materials.

A portable magnetic electrochemical sensor for highly efficient Pb(II) detection based on bimetal composites from Fe-on-Co-MOF.

The practical, sensitive, and real-time detection of heavy metal ions is an essential and difficult problem. This study presents the design of a unique magnetic electrochemical detection system that can achieve real-time field detection. To enhance the electrochemical performance of the sensor, Fe2O3@C-800, Co/CoO@/C-600, and CoFe2O4@C-600 magnetic composites were synthesized using three MOFs precursors by the solvothermal method. And the morphology structure and electrochemical properties of as-prepared magnetic composites were researched by X-ray diffraction (XRD), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), specific surface area and porosity analyzer (BET) and differential pulse voltammetry (DPV). The results shown that these composites improve conductivity and stability while preserving the MOFs basic frame structure. Compared with the monometallic MOFs-derived composites, the synergistic effect of the bimetallic composite CoFe2O4@C-600 can significantly enhance the electrochemical performance of the sensor. The linear range for the detection of lead ions was 0.001-60 µM, and the detection limit was 0.0043 µM with a sensitivity of 22.22 µA µM·cm-2 by differential pulse voltammetry. The sensor has good selectivity, stability, reproducibility and can be used for actual sample testing.