Inductively Coupled Plasma Optical Emission Spectrometry Research Articles

Multiresidue Methods Analysis to Detect Contamination of Selected Metals in Honey and Pesticides in Honey and Pollen

Honey, a natural food with a rich history, is produced by honeybees and other species of bees from nectar, other plant fluids, and honeydew of sap-sucking insects. During foraging, these bees may be exposed to plant protection products (PPPs), metals, and metalloids, potentially leading to residues in honey and hive products that could have a negative impact on human safety. Recognizing the lack of an appropriate methodology for pesticide contamination of honey and other hive products, this research aims to support the need for studies on residues in pollen and bee products for human consumption to establish safe maximum residue levels (MRLs) for consumers. A UHPLC-MS/MS residues method and a modified QuEChERS extraction were applied to simultaneously determine 237 pesticide residues in honey and pollen. The study in North Sardinia analyzed honey and pollen samples from six areas for pesticide residues and verified 27 heavy metals and metalloid residues using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The data obtained showed residues at levels close to the LOQ of the method, cycloate in a few samples of pollen, and dichlorvos, zoxamide, cycloate, and chlorantraniliprole in honey samples. All samples showed the absence of heavy metal contamination. Overall, no risk to human health was identified. The results of this study confirm that honey and pollen may be a good bioindicator of environmental contamination of a wide area surrounding honeybee hives.

Nutritional Risks of Heavy Metals in the Human Diet—Multi-Elemental Analysis of Energy Drinks

Background: In recent years, the consumption of energy drinks (EDs) by adolescents and young adults has increased significantly, so concerns have been raised about the potential health risks associated with excessive ED consumption. Most analyses on EDs focus on the caffeine content. Research on the content of minerals (essential and toxic) in energy drinks can be considered scarce. Therefore, there is a need for research stating the actual status of heavy metal content in commercially available energy drinks. Methods: This research presents the determination of the total concentrations of macro-elements and trace elements (TEs), such as Na, K, Mg, Ca, Al, Cr, Co, Cu, Fe, Mn, Ni, B, Zn, V, Sr, Ba, Pb, Cd, and As in nine samples of energy drinks using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) techniques. Results: The order in the content of macro-minerals in the EDs was as follows: Na > K > Mg > Ca. The results showed that ED 1, ED 3, and ED 7 samples had the highest micro-mineral concentrations. All the samples had a hazard quotient and hazard index < 1, indicating no non-carcinogenic risk from exposure to single or multiple heavy metals in both the adolescent and adult age groups. Some samples exceeded the threshold limit of acceptable cancer risk for As, Ni, and Cr in both adolescents and adults. Conclusions: This assessment showed that in addition to health implications based on the caffeine content of EDs, there might be a carcinogenic risk associated with the toxic element content of these beverages. This research also highlights notable differences in the TE levels among various ED brands, which may have important implications for consumer well-being and health.

3D‐Printable Polymer Filters for the Selective Complexation of Silver Ions

ABSTRACTThis study presents the fabrication of polymeric filters, which are able to selectively bind silver ions from aqueous solution. Those filters are fabricated within an easy approach via 3D‐digital light processing (DLP)‐printing enabling a tailor‐made design. In first order, an acrylamide containing a benzo‐trithiacrown‐ether (BTCE) functionality is synthesized. This monomer is further 3D‐printed via layer by layer photo‐polymerization together with commercially available comonomers, resulting in polymer networks containing the BTCE‐groups in their side chains as selective binding moiety for silver ions. Within isothermal‐titration calorimetry (ITC) measurements, the complexation abilities of the BTCE to bind the Ag+ ions are determined. Furthermore, the resulting 3D‐printed filters are investigated regarding their complexation behavior, in a detailed fashion applying inductively coupled plasma optical emission spectroscopy (ICP‐OES).

How does cloning change phenolics, minerals and antioxidant activity in Helichrysum arenarium (L.) Moench (Clone A, Clone B)?

Tissue culture and cloning are valuable techniques in plant biology research as they enable the production of genetically identical plants, which may be utilized for many purposes such as crop enhancement, plant breeding, and genetic manipulation. Helichrysum arenarium (L.) Moench (HA), also known as immortelle or strawflower (Asteraceae), is a species of flowering plant in the sunflower family. In this study, the aerial part of two Clones (Clone A, Clone B) of H. arenarium were used to consider the effect of Clones on the phenolics, minerals, and antioxidant activities. The methanol extracts were analyzed and compared for phenolic compounds and antioxidant activities. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) is a widely used method for the determination of a wide range of elements in plant materials, including macro and micro elements. Calcium and potassium are the major mineral elements. The phenolics were identified and quantified using high performance liquid chromatography combined with tandem mass spectrometry (HPLC-MS/MS). The highest caffeic acid was determined in the methanolic extract, followed by protocatechuic aldehyde and protocatechuic acid.

Pd anchored to layered double hydroxide modified with chitosan and Echinophora platyloba extract as a nanocatalyst for the formylation of aryl iodides with formic acid.

The novel Zn-Cu-Al layered double hydroxide (LDH) encapsulated within a chitosan/glutaraldehyde matrix, designated as LDH@Cs/G@Pd, was synthesized through simplified methodologies for the preparation of aromatic aldehyde derivatives. Formic acid served as the carbon monoxide source and hydrogen donor, while chitosan/glutaraldehyde acted as the linking agent between the substrate and palladium nanoparticles, with Echinophora platyloba extract functioning as the reducing agent for palladium. The characterization of LDH@Cs/G@Pd was conducted using a variety of analytical techniques, including Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, and inductively coupled plasma optical emission spectroscopy (ICP-OES). The results indicate that the catalyst has been successfully synthesized and Showed promising characteristics for its intended application. Afterward, the catalyst was utilized to Synthesize aromatic aldehydes. The catalyst developed in this study demonstrated a synthesis yield of approximately 95 % for aromatic aldehydes, confirming its potential as an effective candidate for industrial applications.

Cu-ZnO/CuO porous heterostructures for adsorption of lead ion

The pure ZnO and Cu-ZnO/CuO (CuZC) heterostructures had been successfully synthesized using an orange fruit peel extract-based solution combustion synthesis approach. The XRD result revealed the wurtizite phase structure of ZnO NPs with a crystallite size of 12 nm for the CuZC heterostructures. The indirect UV–vis-DRS analysis revealed the band gap energy of ZnO NPs and CuZC heterostructure to be 3.16 and 2.95 eV, respectively. Porous morphology and absence of impurities were confirmed from the FESEM-EDS and TEM/HRTEM analyses. The lead (Pb) ion adsorption potential of NPs was analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) technique. The removal efficiency for CuZC heterostructure at an initial Pb ion concentration of 20 mg/L is 96.3 %. Based on the adsorption kinetics and isotherm models fitting value, dominance of the chemisorption adsorption process was confirmed. The doped NPs have the potential to be used as an effective and favorable adsorbent material for remediation of heavy metal ions from water solutions.

Amino-grafted Ti3C2 MXene nano-sheets doped with zinc-phytic acid complex; An advance 2D-nanocarrier toward improving epoxy coating smart anti-corrosion performance

MXene's unique structure and properties endow it with new applications in corrosion studies, drawing the attention of material scientists. In the present study, the MXene sheets modified by 3-Aminopropyltriethoxysilane (APTES) were utilized as carriers of zinc cations and phytic acid (Ph) (F-M@Zn-Ph) and then introduced into the epoxy coating for smart anti-corrosion application. Characterization tests such as X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA), Field Emission Scanning Electron Microscopy (FE-SEM), Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), and zeta potential were carried out to validate the synthesis of F-M@Zn-Ph. The fabricated composite coatings' protective, and adhesion properties were studied by EIS, cathodic disbondment (CDT), salt spray (SST), and pull-off tests. Solution phase studies exhibited that the F-M@Zn-Ph sample inhibited mild steel corrosion up to 91 % during 48 h of immersion. Investigating the scratched coatings showed that the total resistance (RT) value for the F-M@Zn-Ph/EP sample enhanced by about 58 % compared to the Blank/EP during 48 h of immersion which denotes the self-healing properties of the coating. EIS results of the intact F-M@Zn-Ph/EP sample displayed the highest log|Z|0.01Hz value (10.83 Ω cm2) after 14 weeks of immersion. Along with the barrier properties improvement, the F-M@Zn-Ph/EP coating showed a small adhesion loss of 4 %.

Spicing up nutrition: investigation of trace elements in some spices locally sold in two markets in Kisumu-Kenya.

Spices are integral to Kenyan cuisine, adding depth of flavour and aroma to dishes. Information on the levels of macro- and micronutrients in these spices is scarce, as they are sold locally in Kisumu City, Kenya; however, these species have medicinal value. The study reports the trace elements composition of eight selected spices (black pepper, cloves, ginger, cardamom, turmeric, cumin, red chillies, and garlic) sold in two open-air markets in Kisumu City. The trace elemental compositions for Zn, Ca, Fe, S, K, Na, P, Mg, Mn, B, Co, Li, Cu, Pb, and Cd were analysed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Ginger had the highest mean concentrations of most essential elements, K (5767.86 ± 43.44mg/kg), Mg (4615.36 ± 76.27mg/kg), B (132.08 ± 0.66mg/kg), Li (33.52 ± 0.84mg/kg), Mn (365.29 ± 2.22mg/kg), and Zn (70.44 ± 0.85mg/kg), followed by Ca (5290.44 ± 147.34mg/kg), Na (1361.88 ± 41.01mg/kg), P (3954.25 ± 122.68mg/kg), and S (4031.88 ± 106.95mg/kg), while turmeric had the lowest. The concentrations of macro-elements in spices from the Kibuye market were slightly higher than those from the Jubilee market; however, these differences were not statistically significant (p < 0.05). Concentrations of Pb and Cd heavy metals were detected and reported for all spices in the two markets, although the levels were below the WHO standard; hence, the spices are safe for use as supplements for essential trace elements in addition to their medicinal uses.

Effect of inappropriate solid waste on microplastic contamination in Balasore district and its aquatic environment

BackgroundMicroplastic infection is now one of the world’s key environmental concerns. The most significant causes of microplastic contamination in aquatic ecosystems are coastal villages, coastal landfill sites, shipping activities and coastal dumping areas. Microplastic ingestion has been described in an inclusive assortment of aquatic ecosystems from different trophic levels. This paper provides scientific evidence of microplastic contamination in solid waste from various coastal sites in the Balasore district.ResultsThe coastal village environment is composite sand soils and comprises numerous contaminants that have substantial effects on the detection of characterization results. Significant differences in the results of ultraviolet–visible (UV–Vis) spectroscopy determine many pollutants that are possibly affected by different aspects, including sampling and instrumental settings. Inductively coupled plasma optical emission spectroscopy (ICP-OES) has been applied for the first time to the detection of microplastic content in solid wastes. In comparison with other techniques like Fourier transform infrared (FTIR) spectroscopy, it allows the detection of smaller microparticles. Microplastics in the solid wastes occur at variable size from nm to µm and inductively coupled plasma optical emission spectroscopy with Fourier transform infrared techniques are suitable for screening. In addition, gas chromatography mass spectrometry (GCMS) is becoming a valuable component of analytical platforms for monitoring plastic content. Scanning electron microscopy (SEM) imaging also detects different shapes of microplastics in solid wastes.ConclusionsOur study offers fresh perspectives on critical environmental areas for further research as well as how rural populations worldwide should be involved in the future studies on plastic pollution. The presence of microplastics in solid waste has led to increased scrutiny and calls for regulation. Governments and organizations are exploring policies to reduce plastic waste and mitigate its impacts on the environment and human health.

Assessment of Elemental Composition in Multivitamin Preparations Marketed in Libya: Implications for Safety and Efficacy

This study evaluates the actual and labeled amounts of macro and trace elements in five multivitamin preparations marketed in Libya, utilizing inductively coupled plasma optical emission spectrometry (ICP-OES). The analysis focuses on essential minerals such as calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), manganese (Mn), selenium (Se), and zinc (Zn), alongside common heavy metals including arsenic (As), cadmium (Cd), and lead (Pb). The findings reveal significant discrepancies between the actual and labeled amounts of certain elements, raising concerns regarding the safety and efficacy of these supplements for long-term consumption.

Natural Illite Liquid Mineral Extract: A Clinical Study of an Emulsion to Improve Skin Barrier Function

In this study, we evaluated the skin barrier improvement effect of a natural liquid mineral extract of mica clay, commonly used in cosmetics. The mica particles have an average size of approximately 4.77 μm, with a range around 10 μm. The specific surface area is about 8.8 m2/g, the average pore volume is 0.02 cm3/g, and the pore size is 10.82 nm. The extraction process involved mixing the mineral materials with distilled water for 2 days. The final extraction solution contained approximately 6 mg/L of potassium, as determined using inductively coupled plasma optical emission spectrometry (ICP-OES). A cosmetic emulsion containing the natural illite liquid mineral extract was assessed for stability in pH, viscosity, color, and odor under various conditions, including 4 °C, 25 °C, 45 °C, temperature cycling, and daylight, over 3 months. A placebo-controlled clinical trial was conducted to evaluate the skin barrier improvement and soothing effects on skin damaged by sodium lauryl sulfate (SLS) exposure or tape stripping. The test product demonstrated a statistically significant improvement in transepidermal water loss (TEWL) and skin redness compared to the control product. Therefore, the natural illite liquid mineral extract appears to enhance skin barrier function and soothe damaged skin, suggesting its potential therapeutic benefits.

Impact of gradient zero-valent iron pollution from steel works on soil microaggregate geochemical processes and dissipative structures

Abstract: Zero-valent iron (ZVI) contamination from steel works poses significant threats to soil quality and ecosystem health, particularly affecting soil microaggregates, which are fundamental to soil structure and function. In this study, we systematically investigated the impact of gradient ZVI pollution on the organic geochemical environment of soil microaggregates around steel works located in the core water source area of the Middle Route of the South-to-North Water Diversion Project in China. Advanced analytical techniques, including X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), were employed to comprehensively characterize the geochemical processes, mineralogy, and organic matter environment of soil microaggregates. The findings revealed that soils near the steel works were acidified and strongly oxidized, with heavy metal contents, particularly Fe, significantly decreasing with increasing distance from the steel works (Fe content decreased from 27,516.2 mg/kg to 23,492.6 mg/kg). The pH of soils near the steel works was lower, while oxidation-reduction potential (ORP) and electrical conductivity were higher. XPS analysis indicated a higher content of reactive oxygen species (ROS) near the steel works and significantly lower soil organic matter content. The iron valence distribution showed spatial differences, with higher Fe2⁺ content on the surface of soil microaggregates near the steel works and Fe³⁺ dominating in areas farther away. These results suggest an evolutionary sequence of ZVI from Fe (0) oxidation to Fe(II) and then to Fe(III). The formation of dissipative structures in soil microaggregates due to ZVI contamination significantly affects soil physicochemical properties and the organic environment. This study provides valuable insights into the multifaceted impacts of industrial activities on soil ecosystems and offers a scientific basis for soil conservation and remediation strategies.

Pollution Level and Assessment of a Tropical River in Pahang Malaysia

Rivers are often contaminated with metals. This study was conducted on the Jempul River in Jengka, Pahang, Malaysia, due to the agricultural activities carried out along this river. The aims are to investigate the levels of certain metals (namely Al, Fe, Mn, and Pb), identify their likely sources, assess their toxicity loads, and estimate the associated health risks. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to determine metal concentrations. The concentrations were discovered in the following order: Fe > Al > Mn > Pb, for both dry and wet conditions. The highest concentration in water sample was observed for Fe (1.28 mg/l) in the dry condition and the lowest was detected for Pb (0.04 mg/l) in the wet condition. Principal component analysis (PCA) indicated that the metals originate from natural and anthropogenic sources. Based on metal toxicity load (MTL) calculations, it is recommended that approximately 73% of Pb, 60% of Mn, and 58% of Al be eliminated from the river water to ensure its safety. Children are more susceptible to non-cancer and cancer hazards than adults. This study suggests that extensive exposure assessment and detailed monitoring of water quality indicators should be carried out.

Thermal stability of valuable metals in lithium-ion battery cathode materials: Temperature range 100–400 °C

Lithium is crucial in lithium-ion batteries (LIBs), serving as a main component of the electrolyte and cathode. Elements such as cobalt, nickel, and manganese are also vital for high performance, energy density, and stability. This study aimed to examine the behaviour of end-of-life cathode material (LiNi0.6Mn0.2Co0.2O2) and its valuable metals after exposure to temperatures between 100 and 400 °C, comparing it with untreated material. The lithium content cannot be reliably determined by conventional analytical methods, so inductively coupled plasma optical emission spectroscopy (ICP-OES) was chosen for this purpose. For ICP-OES measurements, samples were dissolved in different solvents for a specified time, and the concentrations of lithium, nickel, manganese, and cobalt were measured. From the measured values, their theoretical yields were calculated. Due to the annealing at given temperatures and subsequent dissolution, this step can be considered as the first stage of the pyrometallurgical-hydrometallurgical process used in battery recycling. The study was complemented by further analyses to monitor the effect of annealing temperatures on the properties of the material. Based on the results, it was found that the highest theoretical yield in this temperature range was for material annealed at 400 °C and dissolved in 20 % nitric acid for 4 h.

Adding More Shape to Nanoscale Reference Materials─LiYF4:Yb,Tm Bipyramids as Standards for Sizing Methods and Particle Number Concentration.

The increasing industrial use of nanomaterials calls for the reliable characterization of their physicochemical key properties like size, size distribution, shape, and surface chemistry, and test and reference materials (RMs) with sizes and shapes, closely matching real-world nonspheric nano-objects. An efficient strategy to minimize efforts in producing nanoscale RMs (nanoRMs) for establishing, validating, and standardizing methods for characterizing nanomaterials are multimethod nanoRMs. Ideal candidates are lanthanide-based, multicolor luminescent, and chemically inert nanoparticles (NPs) like upconversion nanoparticles (UCNPs), which can be prepared in different sizes, shapes, and chemical composition with various surface coatings. This makes UCNPs interesting candidates as standards not only for sizing methods, but also for element-analytical methods like laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), quantitative bioimaging methods like X-ray fluorescence computed tomography (XFCT), and luminescence methods and correlative measurements. Here, we explore the potential of two monodisperse LiYF4:Yb,Tm bipyramids with peak-to-peak distances of (43 ± 2) nm and (29 ± 2) nm as size standards for small-angle X-ray scattering (SAXS) and tools for establishing and validating the sophisticated simulations required for the analysis of SAXS data derived from dispersions of nonspheric nano-objects. These SAXS studies are supplemented by two-dimensional (2D)-transmission electron microscopy measurements of the UCNP bipyramids. Additionally, the particle number concentration of cyclohexane dispersions of these UCNP bipyramids is determined by absolute SAXS measurements, complemented by gravimetry, thermogravimetric analysis (TGA), and inductively coupled plasma optical emission spectrometry (ICP-OES). This approach enables traceable particle number concentration measurements of ligand-capped nonspheric particles with unknown chemical composition.

Exploring Pt-Impregnated CdS/TiO2 Heterostructures for CO2 Photoreduction.

This work focuses on the production of methane through the photocatalytic reduction of carbon dioxide using Pt-doped CdS/TiO2 heterostructures. The photocatalysts were prepared using P25 commercial titania and CdS synthesized through a solvothermal methodology, followed by the impregnation of Pt onto the surface to enhance the physicochemical properties of the resulting photocatalysts. The pure and heterostructure-based materials were characterized using X-ray diffraction (XRD), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy (UV-Vis), ultraviolet photoelectron spectroscopy (UPS), and photoluminescence spectroscopy (PL). The obtained results show the successful synthesis of the heterostructure impregnated with Pt. Moreover, the observed key role of CdS and Pt nanoparticles in the final semiconductor is to reduce the electron-hole pair recombination rate by acting as an electron sink, which slows down the recombination process and increases the photocatalyst efficiency. Thus, Pt-doped CdS/TiO2 heterostructures with the best observed composition presents better catalytic activity than P25 titania with methane production values being 460 and 397 µmol CH4/g·h, respectively.

Evaluation of Health Risk and Heavy Metal Pollution Caused by Dust Storms in Zabol City.

This study investigated the concentrations and compositions of specific elements in total suspended particulate (TSP) samples and the associated ecological, carcinogenic, and non-carcinogenic risks related to the inhalation, ingestion, and dermal absorption of heavy metals. The study focused on adult and pediatric populations in the highly dust-polluted city of Zabol, Iran, during 2022-2023. The samples were analyzed by using inductively coupled plasma optical emission spectrometry (ICP-OES). The concentration of metals in milligram per kilogram (mg/kg) was as follows: Al (75053) > Ca (8206) > Fe (5439) > Mg (5323) > Zn (15.27) > Pb (3.66) > Cr (3.38) > Cd (0.011); according to the results, the highest amount of metals related to aluminum and calcium in dust particles. The calculated individual indices, including the ecological risk index (ERI), pollution factor (Cfi), and geographic accumulation index (Igeo), indicated that calcium exhibited minimal pollution, while the metal samples (Al, Mg, Fe, Cd, Cr, Pb, and Zn) were categorized as uncontaminated. The results revealed that the ecological risk factor (Er) is below 40, indicating a low level of contamination. Additionally, the pollution level determined by the ecological risk potential (RI) was less than 150, suggesting a low probability of contamination. Ingestion posed the highest average hazard quotient (HQ) values for both children and adults in terms of non-carcinogenic risk assessment, while cutaneous and inhalation exposures showed lower values. Furthermore, the hazard index (HI) for heavy metals remained below the safe threshold of 1. The risk index (RI) values for lead, cadmium, and chromium were all below 1 × 10-6 in both adult and pediatric populations. The United States Environmental Protection Agency (USEPA) guidelines suggest an acceptable level of carcinogenicity for all heavy metals, indicating a potential risk of cancer associated with the presence of these metals in suspended particles in Zabol.

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.

Conversion of Sugars to Lactic Acid using Homogeneous Niobium-Substituted Polyoxometalate Catalysts.

The catalytic conversion of biomass into high-value chemicals is an increasing field of research. This study uniquely investigates the use of various Keggin-type heteropoly salts (HPS) for the chemical conversion of sugars into lactic acid under mild conditions of 160 °C and 20 bar N2. In the first phase, Nb- and V-substituted HPSs were employed to synthesize lactic acid from dihydroxyacetone, an intermediate in the conversion of sugars to lactic acid. Results indicated that increasing the Nb content within the Keggin structure enhances the yield of lactic acid while reducing the formation of the byproduct acetaldehyde. A correlation was established between the redox activity of the HPS and the catalytic performance. The most active catalyst, Na5[PNb2Mo10O40], (NaNb2) achieved a lactic acid yield of 20.9 % after 1 h of reaction. In the second phase of the study, NaNb2 was applied for the conversion of different sugars including glucose, fructose, mannose, sucrose, xylose, and cellobiose. It was demonstrated that the catalyst remains active for complex hexoses, achieving lactic acid yields of up to 12 %. Post-mortem analysis using infrared (IR) and Raman spectroscopy, nuclear magnetic resonance (NMR), and inductively coupled plasma optical emission spectrometry (ICP-OES) confirmed the stability of NaNb2.

An Efficient Fluorescent Chemosensing Probe for Total Determination and Speciation of Ultra-Trace Levels of Mercury (II) Species in Water.

The current study reports a novel fluorescent chemosensor based on the tagging agent 4,5,6,7-tetrachloro-2',4',5',7'-tetraiodofluorescein (Rose Bengal, RB) for detection of trace levels of Hg2+in environmental water. The established probe has been based upon liquid-liquid extraction (LLE) of the developed ternary complex ion associate {[Hg (bpy)2]2+.[RB]2-} of Hg2+ -2,2- bipyridyl complex [Hg (bpy)2]2+ and RB at pH 9.0 onto chloroform and measuring the resulting fluorescence enhancement signal intensity at λex/em = 570/ (580-600) nm. The limits of detection (LOD) and quantification (LOQ) of for Hg2+ was calculated to be 6.06 and 20 nM with a linear dynamic range (LDR) of 0.02-20µM, respectively. The stability constant, stoichiometry, chemical equilibria, and the thermodynamic parameters (ΔH, ΔS, and ΔG) of the developed ion associate were evaluated and assigned. Student's t and F tests at 95% confidence were fruitfully used for validation of the proposed methodology for Hg2+ detection in water samples with the aid of inductively coupled plasma-optical emission spectrometry (ICP-OES). The established strategy was successfully applied for detection of trace levels of Hg2+ in water samples with acceptable results. The proposed probe was satisfactorily applied for total determination and speciation of Hg in various water samples. Integrating the functional chelating agent onto associate formation to improve the selectivity and sensing properties of the LLE combining sensing probe towards target analyte in water represent the main interest.