Inductively Coupled Plasma With Optical Emission Spectrometry Research Articles

Snow dumping station – A considerable source of tyre wear, microplastics, and heavy metal pollution

Snow dumping stations can be a hotspots for pollutants to water resources. However, little is known about the amount of microplastics including tyre wear particles transported this way. This study investigated microplastics and metals in snow from four snow dumping stations in Riga, Latvia, a remote site (Gauja National Park), and a roof top in Riga. Microplastics other than tyre wear particles were identified with Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) (>500 µm) and focal plane array based micro-Fourier Transform Infrared (FPA-µFTIR) imaging (10–500 µm), tyre wear particles by Pyrolysis Gas Chromatography-Mass Spectroscopy (Py-GC–MS), and total metals by Inductively Coupled Plasma with Optical Emission Spectroscopy (ICP-OES). Microplastics detected by FTIR were quantified by particle counts and their mass estimated, while tyre wear particles were quantified by mass. The concentrations varied substantially, with the highest levels in the urban areas. Microplastic concentrations measured by FTIR ranged between 26 and 2549 counts L−1 of melted snow with a corresponding estimated mass of 19–573 µg/L. Tyre wear particles were not detected at the two reference sites, while other sites held 44–3026 µg/L. Metal concentrations varied several orders of magnitude with for example sodium in the range 0.45–819.54 mg/L and cadmium in the range 0.05–0.94 µg/L. Correlating microplastic measured by FTIR to metal content showed a weak to moderate correlation. Tyre wear particles, however, correlated strongly to many of the metals. The study showed that snow can hold considerable amounts of these pollutants, which upon melting and release of the meltwater to the aquatic environment could impact receiving waters.

Plant tissue characteristics of Miscanthus x giganteus

As part of a study identifying relationships between environmental variables and insect distributions within a bioenergy crop, giant miscanthus (Miscanthus x giganteus) samples were collected in October 2016 at 33 locations within a field in southeast Georgia, USA. At each location, one plant sample was collected every 3 to 4 m along a 15 m transect, resulting in 5 replicates per sampling location. The plant samples were separated into leaves and stems, dried, and ground. The chemical composition of the ground material was assessed by measuring total carbon and nitrogen, total macro- and micronutrients (aluminum, arsenic, boron, calcium, cadmium, cobalt, chromium, copper, iron, potassium, magnesium, manganese, molybdenum, sodium, nickel, phosphorus, lead, sulfur, selenium, silicon, titanium, vanadium, and zinc) using Inductively Coupled Plasma with Optical Emission Spectroscopy (ICP-OES), and optical characteristics of the water extractable organic matter (WEOM) using UV-Visible and Fluorescence Excitation Emission Matrix (EEM) spectroscopy. This dataset will be useful to identify relationships between the chemical composition of giant miscanthus tissues and pest distributions within a bioenergy crop field.

Combined Thermal Runaway Investigation of Coin Cells with an Accelerating Rate Calorimeter and a Tian-Calvet Calorimeter

Commercial coin cells with LiNi0.6Mn0.2Co0.2O2 positive electrode material were investigated using an accelerating rate calorimeter and a Tian-Calvet calorimeter. After cycling and charging to the selected states of charge (SOCs), the cells were studied under thermal abuse conditions using the heat-wait-seek (HWS) method with the heating step of 5 K and a threshold for self-heating detection of 0.02 K/min. The onset temperature and the rate of the temperature rise, i.e., the self-heating rate for thermal runaway events, were determined. The morphology of the positive electrode, negative electrode and the separator of fresh and tested cells were compared and investigated with scanning electron microscopy (SEM). Furthermore, the microstructure and the chemical compositions of the individual components were investigated by X-ray diffraction (XRD) and inductively coupled plasma with optical emission spectrometry (ICP-OES), respectively. In the Tian-Calvet calorimeter, the coin cells with the selected SOCs and the individual components (positive electrode, negative electrode and separator) were heated up with a constant heating rate of 0.1 °C/min (ramp heating mode). Simultaneously, the heat flow signals were recorded to analyze the heat generation. The combination of the three different methods—the HWS method using the ES-ARC, ramp heating mode on both cells and the individual components using the Tian-Calvet calorimeter—together with a post-mortem analysis, give us a complete picture of the processes leading to thermal runaway.

Multi-elementalna analiza realnih uzoraka vode sa teritorije Požege, Srbija

The aim of this study was to examine the quality of real samples of drinking water, collected from the territory of the city of Požega and the surrounding rural areas. An analytical technique of inductively coupled plasma with optical emission spectrometry (ICP-OES) was used to determine the concentrations of macro and microelements in water samples. The obtained results were compared with the maximum allowed concentrations of elements specified by the national Regulation on hygienic quality of drinking water, as well as the recommendations of the World Health Organization (WHO) and the US Environmental Protection Agency (EPA). The analysed waters were low-mineralized (<1000 mg/L), calcium waters, with low sodium content. The concentrations of all tested elements in the water samples were within the allowed values. There were obvious differences in chemical composition between surface water samples and groundwater samples. All tested waters can be safely used for irrigation, because the risk of soil salinization, sodium accumulation and harmful effects of boron on crops was assessed as insignificant.

Toxic element levels in ingredients and commercial pet foods

Nowadays, there is a growing concern about contamination of toxic metals (TM) in pet food due to the great potential for health risks of these elements. TM concentrations in commercial pet foods (n = 100) as well as in ingredients used in their composition (n = 100) were analyzed and compared to the Food and Drug Administration (FDA) maximum tolerable level (MTL), and the TM concentrations found in the different sources of carbohydrate, protein, and fat were compared. The TM concentrations were determined by inductively coupled plasma with optical emission spectrometry (ICP-OES). Concentrations above the MTL for aluminum, mercury, lead, uranium, and vanadium were observed in both dog and cat foods, and the percentage of dog foods that exceeded the MTL of these TM were: 31.9%; 100%; 80.55%; 95.83%; and 75%, respectively, and in cat foods: 10.71%; 100%; 32.14%; 85.71%; 28.57%, respectively. The MTL values of these TMs and the mean values in dog foods (mg/kg dry matter basis) (MTL [mean ± standard deviation]) were: aluminum: 200 (269.17 ± 393.74); mercury: 0.27 (2.51 ± 1.31); lead: 10 (12.55 ± 4.30); uranium: 10 (76.82 ± 28.09); vanadium: 1 (1.35 ± 0.69), while in cat foods were: aluminum: 200 (135.51 ± 143.95); mercury: 0.27 (3.47 ± 4.31); lead: 10 (9.13 ± 5.42); uranium: 10 (49.83 ± 29.18); vanadium: 1 (0.81 ± 0.77). Dry foods presented higher concentrations of most TM (P < 0.05) than wet foods (P < 0.05). Among the carbohydrate sources, there were the highest levels of all TM except cobalt, mercury, and nickel in wheat bran (P < 0.05), while among the protein sources, in general, animal by-products had higher TM concentrations than plant-based ingredients. Pork fat had higher concentrations of arsenic, mercury, and antimony than fish oil and poultry fat. It was concluded that the pet foods evaluated in this study presented high concentrations of the following TM: aluminum, mercury, lead, uranium, and vanadium.

Mineral Composition of Herbaceous Species Seseli rigidum and Seseli pallasii: a Chemometric Approach

Nutrients play an essential role in many metabolic processes whose deficiency or excess can be harmful to the plant itself and through the food chain to both animals and humans. Medicinal plants used in the food and pharmaceutical industries can be contaminated with increased concentrations of heavy metals. The plant species Seseli rigidum and Seseli pallasii from the Balkan Peninsula are used in traditional medicine and spices in the diet, so it was necessary to determine the mineral composition to ensure their safe application. In this work, the mineral composition was determined in medicinal species of the genus Seseli using inductively coupled plasma with optical emission spectrometry (ICP-OES). Two multivariate statistic methods -principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to distinguish samples regarding their mineral composition. The mineral composition of both studied species is following the literature data. The results obtained using multivariate statistics methods agree and distinguish certain parts of the tested plants based on the highest content of micro, macro, or trace elements.

Metabolomic, Ionomic and Microbial Characterization of Olive Xylem Sap Reveals Differences According to Plant Age and Genotype

Vascular pathogens are the causal agents of main diseases threatening the health and growth of olive crops worldwide. The use of endophytic microorganisms represents a challenging and promising strategy for management of vascular diseases in olive. Although current research has been focused on analyzing the structure and diversity of the endophytic microbial communities inhabiting the olive xylem, the characterization of this ecological niche has been overlooked and to date remain unexplored, despite that the characterization of the xylem sap composition is essential to unravel the nutritional requirements of xylem-limited microorganisms. In this study, branches from plantlets and adult olive trees of cultivars Picual and Arbequina were selected to characterize the chemical and microbial composition of olive xylem sap extracted using a Scholander pressure chamber. Metabolome and ionome analyses of xylem sap were performed by proton nuclear magnetic resonance (NMR) spectroscopy-based and by inductively coupled plasma with optical emission spectroscopy (ICP-OES), respectively. Olive xylem sap metabolites included a higher relative percentage of sugars (54.35%), followed by alcohols (28.85%), amino acids (8.01%), organic acids (7.68%), and osmolytes (1.12%). Within each of these groups, the main metabolites in the olive xylem sap were mannitol, ethanol, glutamine, acetic acid, and trigonelline, whereas K and Cl− were the main element and inorganic anion, respectively. Metabolomic profile varied when comparing olive plant age and genotype. The levels of glucose, fructose, sucrose and mannitol, choline, B and PO43− were significantly higher in adult trees than in plantlets for both olive genotypes, whereas NO3− and Rb content showed the opposite behavior. On the other hand, levels of aspartic acid, phenylalanine, and Na were significantly higher in ‘Picual’ than in ‘Arbequina’, whereas Fe showed the opposite behavior, but only for adult trees. Microbiome composition identified Firmicutes (67%), Proteobacteria (22%) and Actinobacteriota (11%) as the main phyla, while at the genus level Anoxybacillus (52%), Cutibacterium (7%), Massilia (6%), and Pseudomonas (3%) were the most representative. Both non-supervised hierarchical clustering analysis and supervised PLS-DA analysis differentiated xylem sap chemical and microbial composition first, according to the age of the plant and then by the olive genotype. PLS-DA analysis revealed that B, ethanol, Fe, fructose, glucose, mannitol, sucrose, and Sr, and Anoxybacillus, Cutibacterium, and Bradyrhizobium were the most significant chemical compounds and bacterial genera, respectively, in the discrimination of adult olive trees and plantlets. Knowledge of the chemical composition of xylem sap will lead to a better understanding of the complex nutritional requirements of olive xylem-inhabiting microorganisms, including vascular pathogens and their potential antagonists, and may allow the better design of artificial growing media to improve the culturing of the olive microbiome.

Photocatalytic Degradation of Phenol Using Photodeposited Pt Nanoparticles on Titania.

In this study, the photodeposition synthesized Pt-titania (Pt/P25) photocatalysts with various amount of Pt (0.5-5.0 wt.%) were characterized in detail by Brunauer-Emmett-Teller surface area analysis (BET), inductively coupled plasma with optical emission spectroscopy (ICP-EOS), X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS UV-vis), attenuated total reflection (ATR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the investigated catalysts was studied towards the photocatalytic degradation of phenol. The best performance was obtained for the 3.0 wt.% Pt/TiO₂. The concentration of photocatalyst, the initial phenol concentration and pH value of the reaction solution was studied in detail. The obtained results show that the reaction rate increases with increasing catalyst concentration and decreases with increasing phenol concentration. The highest degradation efficiency was observed for a neutral pH. In overall, the results of this study show that the Pt/TiO₂ photocatalysts can efficiently improve the decomposition of phenol in the presence of UV light.

Element losses from fields in conventional and conservation tillage in the Atlantic Coastal Plain, Georgia, United States

The elemental composition of soil plays an essential role in crop nutrition, but losses from croplands can negatively impact soil fertility and water quality. We compared the impact of strip tillage (ST) and conventional tillage (CT) on element concentrations and loads in surface runoff and subsurface flow from plots under rotational cotton (<i>Gossypium hirsutum</i> L.) and peanut (<i>Arachis hypogaea</i> L.) production with winter cover cropping. Total element concentrations (calcium [Ca], iron [Fe], potassium [K], magnesium [Mg], manganese [Mn], sodium [Na], phosphorus [P], sulfur [S], silicon [Si], and zinc [Zn]) in surface runoff and subsurface flow samples were measured using Inductively Coupled Plasma with Optical Emission Spectroscopy (ICP-OES). Element loads were estimated by multiplying the element concentrations by the surface runoff and drainage volumes. Significantly greater (<i>p</i> ≤ 0.05) surface runoff loads for all elements (with the exception of K and Zn) were observed from the CT compared with the ST treatment plots only in 2006, likely due to the combined effects of hydrology and the timing of gypsum amendments that year. Surface runoff was the primary hydrologic pathway for Fe, K, Mn, P, Si, and Zn loss while subsurface flow was the primary hydrologic pathway for Ca, Mg, and S loss with both tillage treatments. Lower concentrations of Ca, Mg, Na, and S in the subsurface flow with ST compared to CT suggest that this tillage practice, in conjunction with the proper timing of fertilizer and soil amendment applications (e.g., poultry litter and gypsum) can be an effective method for reducing element losses from croplands. This finding highlights the importance of conservation practices in sustaining healthy cropland soils while reducing element losses and associated environmental impacts.

The determination of phosphate in rocks and iron ores using inductively coupled plasma with optical emission spectroscopy (ICP-OES)

Phosphate is a minor but important constituent of iron ores and is especially undesirable in the production of steel where it is considered a penalty element and is therefore tightly controlled. Iron ore quality must be determined at source, which means that deleterious elements must be accurately determined as an ongoing process. This demands fast, reliable analytical methods for the determination of, amongst others, phosphorus. However, such analysis is severely hampered by the following factors: the standard analytical method employed is X-ray fluorescence (XRF), but the measurements for phosphorus are seriously affected by matrix and inter-element interferences. An alternative technique is inductively coupled plasma with optical emission spectroscopy (ICP-OES), but there are also complications in using ICP-OES. The abundance of phosphorus in rocks is very low, generally under 0.5% wt. ICP-OES is also very insensitive to phosphorus and therefore must use the most sensitive spectral lines for quantification, and, there are serious spectral interferences on these lines by Fe and Cu. This study examines several analytical approaches for the determination of phosphate, using preparation by fusion and analysis by ICP-OES, demonstrating that suitable mathematical procedures and software applications can produce good results for phosphates, comparable to inter-laboratory tests or XRF.

Essential Elements as a Distinguishing Factor between Mycorrhizal Potentials of Two Cohabiting Truffle Species in Riparian Forest Habitat in Serbia.

True truffles (Tuber sp.) that establish ectomycorrhizal symbiosis (ECM) with trees in the Mediterranean and temporal regions have species specific abilities to assimilate soil born elements. Suitable habitats are usually inhabited by few truffle species, while distinguishing their symbiotic potentials appeared very difficult. Two species that commonly inhabit riparian forests in Serbia are the most prized one, Tuber magnatum Pico (Piedmont white truffle) and not so highly valued Tuber brumale Vitt. In order to assess potential differences between their assimilation and accumulation abilities, the differences between contents of elements that may be the subjects of the symbiotic trade between the host plant and fungi were evaluated in accumulation target (ascocarps) and their source (the soil). Essential (K, Na, Ca, Mg, Fe, P, S, and Zn) and essential trace elements (Co, Cr, Cu, Mn, and Se) in truffles and soil samples were determined by means of inductively coupled plasma with optical emission spectrometry (ICP-OES). Their concentrations (mg/kg) in ascocarps were in the range from 1.364±0.591 (Cr) to 10760.862±16.058 (K), while in soil ranged from 23.035±0.010 (Cr) to 20809.300±122.934 (Fe). Element accumulation potential (bioaccumulation factor) was calculated in the system truffle/soil. The statistical approaches were used for establishing the differences, while the possible differentiation between symbiotic potentials of two mycelia in the defined soil conditions was discussed.

An environmentally friendly hydrothermal method of vanadium precipitation with the application of oxalic acid

During the traditional metallurgical process of vanadium (V), an ammonium salt is often employed as the precipitator to form an ammonium vanadate, which converted into V2O5 in the subsequent calcination. Due to the restriction of ammonia emissions by the Chinese government, the vanadium-bearing shale industry in China urgently needs to find out a new environmentally friendly vanadium precipitation method. As the widely used method in the synthesis of VO2, hydrothermal reduction with oxalic acid was firstly introduced into vanadium precipitation in this study. Several factors that affect the vanadium precipitation were studied in the batch tests, such as initial reaction pH, temperature, time, and n(H2C2O4·2H2O)/n(V(V)). A product with 99.53% purity of VO2(B) and 99.47% extent of vanadium precipitation was obtained under the optimized reaction conditions: initial reaction pH of 0.80, time of 8 h, temperature of 493 K, and n(H2C2O4·2H2O)/n(V(V)) of 1.00. Raman spectroscopy, inductively coupled plasma with optical emission spectrometry (ICP-OES) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were also carried out to characterize the product and the results indicated that the product was pure VO2(B) in the form of nanorods. The reaction mechanism of VO2 prepared from stripped vanadium solution is put forward and the transformation of V from stripped vanadium solution to VO2 is proposed as: VO2+ → VO2(C2O4)− → VOC2O4 → VO2. Overall, the present hydrothermal method of vanadium precipitation with the application of oxalic acid has the characteristics of environmentally friendly, short process, simple and efficient.

Levels of heavy metals in a multifloral Saudi honey.

The presence of chemical pollutants, especially heavy metals, affects the quality of honey. The objective of this study was to determine the levels of eight heavy metals (As, Cd, Co, Cr, Cu, Ni, Pb, and Zn) in honey samples from Al-Baha region in Saudi Arabia, using inductively coupled plasma with optical emission spectroscopy (ICP-OES). The highest concentration was found for Zn (1707.93μgkg-1), while the lowest was found for Co (3.04μgkg-1). Cluster analysis and principal component analysis showed that two groups are recognized indicating two different metal sources. The first group includes only Zn and the second group includes the rest of the metals. In view of the recommended and established heavy metal intakes for humans, consumption of Saudi honey from Al-Baha should not be deemed a matter of concern for human health.

Corrosion of nickel-based structural materials for nuclear reactors by molten fluoride salt: From bulk content of corrosion products to elemental imaging of corrosion changes

This work is focused on the study of corrosion treatment of molten fluoride salt (MFS) on three candidate structural materials (Ni, ferritic steel with protective Ni coating, and Ni-based alloy). The samples were exposed to an MFS mixture (60 mol% LiF + 40 mol% NaF) at a temperature of 680 °C for 112, 350 and 1000 h. Their corrosion resistance was tested by the determination of the content of corrosion products in MFS by ICP-OES (Inductively Coupled Plasma with Optical Emission Spectrometry) analysis and comparison of elemental ratios. Distinctive differences in the ratios were found for ferritic steel with protective Ni coating. Morphological changes induced by MFS treatment were revealed and studied by EPMA (Electron Probe Micro Analysis) and LA-ICP-MS (Laser Ablation Inductively Coupled Plasma of Mass Spectrometry). Elemental maps of the corroded area were acquired by both methods. The analyses of corrosion products show that the best candidate material is nickel.

The possibilities of analysis of limestone chemical composition

The aim of this work is to show commonly used procedures and methods for limestone analysis. The samples were measured with Inductively Coupled Plasma with Optical Emission Spectrometry (ICP-OES) for chemical compositions determination. For these measurements, the samples were decomposed by dissolving in acid, melting into solution and decomposed by microwave. Due to the time and financial demands of these analyses, there were an effort how to find a satisfactory method providing sufficient results with less time and financial demands. The X-ray diffraction (XRD) method was first tested, followed by X-ray fluorescence (XRF). Samples were measured in powder and melted into pearls. The evaluation was carried out by using of the Fundamental parameters method and by means of instrument calibration. The method of combustion elemental analysis was selected to determine of the sulfur content.

TOXIC METALS CONTENT AND SAFE USE OF Seseli pallasii HERB

Heavy metals, whether from natural or anthropogenic sources have the ability to migrate between differ ent parts of environment and accumulate in flora and fauna, finally reaching humans through food chain. The possibility that plants might be contaminated by heavy metals should be taken into account, when they are intended for use in pharmaceutical and food industry, because increased concentration of some metals may have an adverse effect on human and animal health. Wild medicinal herb Seseli pallasii have been used in traditional medicine as well as a spice in nutrition, hence an assessment of the presence of toxic metals in it is essential in order to ensure its safe application. Vegetative parts of plant S. pallasii (root, leaf, flower and fruit) from Southeast Serbia were analyzed to assess the content of toxic metals (Cd, Cr, Ni and Pb, using inductively coupled plasma with optical emission spectrometry (ICP-OES). The results have shown that the average concentration of Cd in the aboveground part was almost twice as high 0.21 ppm than in the root 0.11 ppm, concentration of Cr in aerial part was of 0.43ppm, in the root 0.29 ppm, concentration of Ni in the aboveground was of 0.98ppm, while in the root it was of 0.68ppm. The average concentration of Pb in the aboveground part and the root was almost the same (2.31 and 2.15 ppm, respectively). These facts evidenced that the contents of toxic elements in the studied medicinal plant species are below the recommended limits, confirming that S. pallasii from the examined area can be safely used in traditional medicine and nutrition. Key words: Seseli pallasii, toxic metals, ICP, safety .

In vitro study of thimerosal reactions in human whole blood and plasma surrogate samples

Because of its bactericidal and fungicidal properties, thimerosal is used as a preservative in drugs and vaccines and is thus deliberately injected into the human body. In aqueous environment, it decomposes into thiosalicylic acid and the ethylmercury cation. This organomercury fragment is a potent neurotoxin and is suspected to have similar toxicity and bioavailability like the methylmercury cation. In this work, human whole blood and physiological simulation solutions were incubated with thimerosal to investigate its behaviour and binding partners in the blood stream. Inductively coupled plasma with optical emission spectrometry (ICP-OES) was used for total mercury determination in different blood fractions, while liquid chromatography (LC) coupled to electrospray ionisation time-of-flight (ESI-TOF) and inductively coupled plasma-mass spectrometry (ICP-MS) provided information on the individual mercury species in plasma surrogate samples. Analogous behaviour of methylmercury and ethylmercury species in human blood was shown and an ethylmercury-glutathione adduct was identified.

Investigation of the lithium-rich boundary of the Li1+x Mn2−x O4 cubic spinel phase in air

Several compositions of the cubic spinel Li1+x Mn2−x O4−δ phase in the lithium–manganese–oxygen (Li–Mn–O) system were synthesized at 700, 750, and 800 °C in air ( $$ p_{{{\text{O}}_{2} }} $$ = 0.2 atm) to investigate the Li-rich boundary of the cubic spinel phase at these temperatures. The lattice parameters of the several compositions were determined by Rietveld analysis of the measured X-ray patterns, and the Li and Mn contents of the samples were measured using inductively coupled plasma with optical emission spectroscopy (ICP-OES). A Vegard-like dependence of the measured lattice parameter of the cubic spinel phase with Li to Mn ratio exists in the homogeneity range of the cubic spinel. This dependence could be used to derive the boundary of the single phase cubic spinel field in the Li–Mn–O system at 700 and 750 °C at $$ p_{{{\text{O}}_{2} }} $$ = 0.2 atm and to estimate the Li-rich boundary at 800 °C. The results of the present study are compared with two other experimental studies on the homogeneity range of the cubic spinel phase in an attempt to resolve the contradiction between these two studies.

In VitroInhibitory Effect of Clove Essential Oil and Its Two Active Principles on Tooth Decalcification by Apple Juice

The dental erosion or decalcification of enamel is a significant clinical problem. Apple acidic beverages are thought to increase the potential for dental erosion. The purpose of this in vitro study was to investigate the effect of clove essential oil (CEO) and its active principles on tooth decalcification of apple juices. On GC-MS analysis, CEO showed a high content of eugenol (58.29%) and eugenyl acetate (19.10%). Teeth specimens were randomly divided into 5 treatment groups: control, CEO, eugenol, eugenyl-acetate, and fluoride. The specimens were exposed for 24 h and were analyzed for calcium contents using Inductively Coupled Plasma with Optical Emission Spectroscopy (ICP-OES). Data were analyzed using student t-test (P < 0.05). CEO, eugenol, and eugenyl-acetate significantly decreased the decalcification of tooth by the apple juice to only 17, 24, and 21 mgL−1, respectively. Hemolytic activity on human erythrocytes was studied to exclude the possibility of further associated cytotoxicity. It was observed that the CEO and its two lead molecules inhibit the decalcification and/or promote the remineralization caused by the apple juices. The effect of the test compounds appears to be distinct like that of fluoride treatment. CEO may, therefore, serve to be a promising adjunct to fluoride in the treatment of root caries during minimally invasive therapy.

The composition and dissolution in citric extractants of ash from the thermal gasification of pig manure

Ash derived from the thermal gasification of anaerobically digested, dried and pelletized pig manure (GA) was characterized by standard Association of Official Agricultural Chemists (AOAC, 1990) methods of chemical analysis for phosphorus soluble in citric acid (P CA), neutral ammonium citrate (P NAC) and alkaline ammonium citrate (P AAC) for several extraction times. Concentrations of other elements in the three extracts were measured by inductively coupled plasma with optical emission spectroscopy (ICP-OES). The ash had 54.4 g/kg total P (TP), 28.2 g/kg P CA after 6 h extraction and 48.7 mg/kg water soluble phosphorus ( P H 2 O ) and is therefore suitable for use as a P-fertilizer. The very high pH (12) of the ash indicates its strong acid neutralizing ability when applied to acidic soils, although the very high lime content of the ash may reduce P bioavailability in soils. Lime-free gasifier ash (lf-GA) was obtained by treating GA with buffered sodium acetate solution (pH 5) for periods up to 120 h. Removal of calcite equivalent to 70% of initial GA mass reduced pH to 6, increased TP (about 2 times), P H 2 O (10 times) and P CA (1.5 times). X-ray powder diffraction (XRD) patterns of lf-GA indicate that P is mostly present as intermediate hydroxyl-apatite/carbonate-apatite. Apatite grains of various Ca (20.2–48.5%) and P (8.4–17.8%) concentrations were determined by scanning (SEM) and transmission (TEM) electron microscopy with energy dispersive X-ray spectrometry (EDS). Other elements in lf-GA are: Fe (5–15%), Si (<10%), S (<3%) and Na, Mg, Al, Cl, K, Ti (<1% each). The ash contained minor quartz, feldspar and ilmenite.