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Uranium (U) associated with coal can be an important source of U and result in environmental pollution during coal combustion. In this study, we developed a method for measurement of U isotope ratios in coals using multiple‐collector inductively coupled plasma‐mass spectrometry. The 233U‐236U double‐spike was utilised to calibrate the instrumental isotopic fractionation. High‐pressure bomb and dry ashing were adopted to digest the coal samples. The δ238UCRM‐145 values obtained from the two different digestion procedures were in good agreement. The δ238UCRM‐145 of seven coal and one fly ash reference materials are reported. Furthermore, the results of fly ash, bottom ash and feed coal samples reveal that the combustion processes lead to relatively small U isotopic fractionation between the samples within the same coal‐fired power plant, indicating that U isotope data can be used as a tracer for heavy metal pollution resulting from coal combustion. The U isotope measurement method of coal established in this study provides technical support to understand the behaviour of U during coal formation and combustion. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For sample preparation prior to mineral analysis, microwave digestion (~2 h) is quicker and requires lower acid volume as compared to dry (6–8 h) and wet digestion (4–5 h). However, microwave digestion had not yet been compared systematically with dry and wet digestion for different cheese matrices. In this work, the three digestion methods were compared for measuring major (Ca, K, Mg, Na and P) and trace minerals (Cu, Fe, Mn and Zn) in cheese samples using inductively coupled plasma optical emission spectrometry (ICP-OES). The study involved nine different cheese samples with moisture content varying from 32 to 81% and a standard reference material (skim milk powder). For the standard reference material, the relative standard deviation was lowest for microwave digestion (0.2–3.7%) followed by dry (0.2–6.7%) and wet digestion (0.4–7.6%). Overall, for major minerals in cheese, strong correlation was observed between the microwave and the dry and wet digestion methods (R2 = 0.971–0.999), and Bland–Altman plots showed best method agreement (lowest bias), indicating the comparability of all three digestion methods. A lower correlation coefficient, higher limits of agreement and higher bias of minor minerals indicate possibilities of measurement error. [ABSTRACT FROM AUTHOR]

For sample preparation prior to mineral analysis, microwave digestion (~2 h) is quicker and requires lower acid volume as compared to dry (6–8 h) and wet digestion (4–5 h). However, microwave digestion had not yet been compared systematically with dry and wet digestion for different cheese matrices. In this work, the three digestion methods were compared for measuring major (Ca, K, Mg, Na and P) and trace minerals (Cu, Fe, Mn and Zn) in cheese samples using inductively coupled plasma optical emission spectrometry (ICP-OES). The study involved nine different cheese samples with moisture content varying from 32 to 81% and a standard reference material (skim milk powder). For the standard reference material, the relative standard deviation was lowest for microwave digestion (0.2–3.7%) followed by dry (0.2–6.7%) and wet digestion (0.4–7.6%). Overall, for major minerals in cheese, strong correlation was observed between the microwave and the dry and wet digestion methods (R2 = 0.971–0.999), and Bland–Altman plots showed best method agreement (lowest bias), indicating the comparability of all three digestion methods. A lower correlation coefficient, higher limits of agreement and higher bias of minor minerals indicate possibilities of measurement error.

Limited sensitivities of some laser-induced breakdown spectroscopy (LIBS) instruments may impair some applications. Although this drawback can be minimized by instrumental improvements, the complexity of operations and cost increases. In this work the principle of conventional dry ashing for sample preparation was evaluated as a simple and low-cost alternative to improve the sensitivity of LIBS analysis. Botanical, agronomic and industrial samples were analyzed. Samples were dry heated and their LIBS emission signals were evaluated. The results suggest the dry heating caused structural changes in samples providing greater availability of the analyte, which resulted in the enhancement of the signals. As proof of concept, the strategy was applied for Sr determination in plant leaves. Two Sr emission lines, enhanced after sample dry ashing were used. The developed methods showed similar performance featuring a good linear range (10 to 70 μg g−1) with coefficient of correlations higher than 0.99. Additionally, the accurate determination of Sr in apple and peach leaves standard materials was achieved. [ABSTRACT FROM AUTHOR]

A dry ashing method is commonly used to remove organic material from samples prior to geochemical analysis. In the course of this study, the Cd isotope ratios of a series of soil and plant reference materials and samples were studied to evaluate the effect of the dry ashing method on measurement results of Cd isotope ratios. The samples were pre‐treated using the dry ashing method and high‐pressure bomb for comparison. The results show that the digestion using high‐pressure bombs did not lead to Cd loss, but using the dry ashing method would cause different proportions of Cd loss. The whole range of Cd isotope difference between two methods was from −0.07‰ to 3.01‰. There was also an obvious difference in measured Cd isotope ratios from the same leaf sample pre‐treated independently by the dry ashing method, indicating that the amount of Cd loss and the effect on Cd isotope measurement during dry ashing is related to the properties of the samples. Therefore, dry ashing may not be appropriate for the removal of organic material in Cd isotope ratio measurement, especially for samples with high organic contents. The δ114/110Cd values of reference materials NIST SRM 1573a and GSD‐30 are reported for the first time in this study. [ABSTRACT FROM AUTHOR]

This paper proposed phytoliths as promising for identifying and distinguishing sources of fibre in Chinese handmade papers. For an initial methodological exploration, two types of Raw Xuan (unprocessed Xuan paper) and the two plant materials used in making them—namely rice straw and bark from blue sandalwood (Pteroceltis tatarinowii Maxim.)—were collected. The dry ashing method was used to extract phytoliths from Raw Xuan and its plant materials. The results can be summarized as follows. First, phytoliths characteristic of rice (Oryza sativa) were abundant in both rice straw and Raw Xuan. By looking for rice phytoliths, it is possible to tell whether or not rice straw fibre is used in a particular paper. Second, hair cell phytoliths were observed in considerable quantities in blue sandalwood bark, but absent in the examined papers. Heat experiments showed that phytoliths in blue sandalwood were resistant to long-term heat and they would unlikely be eliminated when exposed to the heat in papermaking (with heat source barely above 200°C). It is hypothesised that they dissolved while cooked in an alkaline pH (limewater). Further studies are necessary to understand whether phytoliths in blue sandalwood—while cooked in limewater—undergo morphological changes and, if yes, how.

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Japanese Journal of Food Chemistry & Safety is the property of Japanese Society of Food Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper proposed phytoliths as promising for identifying and distinguishing sources of fibre in Chinese handmade papers. For an initial methodological exploration, two types of Raw Xuan (unprocessed Xuan paper) and the two plant materials used in making them—namely rice straw and bark from blue sandalwood (Pteroceltis tatarinowii Maxim.)—were collected. The dry ashing method was used to extract phytoliths from Raw Xuan and its plant materials. The results can be summarized as follows. First, phytoliths characteristic of rice (Oryza sativa) were abundant in both rice straw and Raw Xuan. By looking for rice phytoliths, it is possible to tell whether or not rice straw fibre is used in a particular paper. Second, hair cell phytoliths were observed in considerable quantities in blue sandalwood bark, but absent in the examined papers. Heat experiments showed that phytoliths in blue sandalwood were resistant to long-term heat and they would unlikely be eliminated when exposed to the heat in papermaking (with heat source barely above 200°C). It is hypothesised that they dissolved while cooked in an alkaline pH (limewater). Further studies are necessary to understand whether phytoliths in blue sandalwood—while cooked in limewater—undergo morphological changes and, if yes, how. [ABSTRACT FROM AUTHOR]

Purpose: To determine the elements in Bryonia alba L. roots, collected from the Crimean Peninsula region in Ukraine. Methods: Dry ashing was used as a flexible method and all elements were determined using atomic absorption spectrometry (AAS) equipped with flame and graphite furnace. Results: The average concentrations of the determined elements, expressed as mg/100 g dry weight of the sample, were as follow: 13.000 for Fe, 78.000 for Si, 88.000 for P, 7.800 for Al, 0.130 for Mn, 105.000 for Mg, 0.030 for Pb, 0.052 for Ni, 0.030 for Mo, 210.000 for Ca, 0.130 for Cu, 5.200 for Zn, 13.000 for Na, 1170.000 for K, 0.780 for Sr, 0.030 for Co, 0.010 for Cd, 0.010 for As, and 0.010 for Hg. Toxic elements such as Cd and Pb were also found but at very low concentration. Among the analyzed elements, K was the most abundant followed by Ca, Mg, P, Si, Fe, Na, and Zn, whereas Hg, As, Cd, Co, Mo, and Pb were found in low concentration. Conclusion: The results suggest that the roots of Bryonia alba L. plant has potential medicinal property through their high element contents present. Moreover, it showed that the AAS method is a simple, fast, and reliable for the determination of elements in plant materials. The obtained results of the current study provide justification for the usage of such fruit in daily diet for nutrition and for medicinal usage in the treatment of various diseases.

Sodium in vacuum gas oils (VGOs), even at trace levels, produces corrosion by-products in the refinery pipelines and it is a significant catalyst poison, especially for those from atmospheric or vacuum distillation units, thus its concentration in middle-distillate petroleum products needs to be controlled. In addition, sodium contamination was an issue in this study, as sodium might be present even in the dust floating in the air. The use of an ultrapure sodium-free water and the disposal of a clean and dust-free room were the key to be successful on the development of this method. Different sample preparation methods were studied as sample preparation optimisation was an important step in this study. Dry ashing by different processes, wet acid digestion with different acid mixtures, wet acid microwave-assisted digestion, and dilution with a proper solvent were tried to find the appropriate sample preparation method. An accurate and precise method for the determination of sodium in vacuum gas oils (VGOs) by ICP-OES at trace levels has been developed by ashing the sample with a new piece of equipment designed and created by the Instituto de Tecnología Cerámica (ITC), that permits to calcine the sample in one hour and avoids analyte losses or analyte contamination. The quantification limit achieved by the whole sodium determination method is lower than 1 mg kg −1 , which allows it to be used as control method in the petrochemical industry. [ABSTRACT FROM AUTHOR]

For the comparison of the digestion and spectroscopic determination methods used to measure boron (B) concentrations in maize shoots, increasing doses of boron (0, 2.5, 5, and 10 mg kg−1B) were applied to soil and maize plants (Zea maysL.) cultivar “Euralis Es Armandi” (FAO 640). The plants were grown under greenhouse conditions. Dried and ground maize shoots were digested according to two digestion procedures of microwave and dry ashing. Boron concentrations were determined using spectrophotometer and inductively coupled plasma-optical emission spectrometry (ICP-OES). The concentrations of boron influenced statistically (p < 0.01) due to the B applications and analysis methods. Spectrophotometric measurement of B amounts of the samples prepared with microwave digestion method was found irrelevant with other indicated methods. However, the ICP-OES measurements were found compatible with the dry ashing also with microwave digestion and suggested as a suitable method to determine boron contents of the maize shoots. [ABSTRACT FROM AUTHOR]

This study evaluated the effectiveness of dry ashing of soils and subsequent spectral subtraction procedure in comparison with alternative chemical methods in accentuating organics for diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic analysis of soil organic matter composition. Chemical oxidation of soil with sodium hypochlorite (NaOCl) and demineralisation by hydrofluoric acid (HF) treatment were assessed as possible alternatives to the dry ashing method. Surface samples (0–10 cm) of four contrasting soils i.e., Ferralsol, Luvisol, Vertisol and Solonetz were used in the study. We observed the spectral changes before and after pre-treatments using DRIFT spectroscopy of bulk soils and their respective four separated density fractions (< 1.8, 1.8–2.2, 2.2–2.6, and > 2.6 g cm − 3 ). Dry ashing of soils altered the absorption bands of gibbsite and goethite in the Ferralsol; however, phyllosilicate bands in the Luvisol, Vertisol and Solonetz remained largely unaffected. The organic bands were incompletely removed by the dry ashing method and shifts in some major organic bands were also noticed. Thus the accuracy of the dry ashed spectral subtraction was limited due to the mineral and organic bands alteration. The NaOCl treatment oxidised labile organic carbon (OC) (e.g., aliphatics) without any mineral alteration, but the rest of the OC fractions remained largely unaffected. Therefore, the result of spectral subtraction of the NaOCl treated samples from original spectra was ambiguous. The HF treatment removed minerals efficiently from both bulk soils and density fractions, which noticeably highlighted the organic bands with little or no mineral interferences in the spectra of the treated samples. HF treatment also removed a small portion of the total OC that was associated with minerals. We conclude that HF treatment was more effective than dry ashing and NaOCl oxidation to accentuate organics in the soil DRIFT spectra, since it provided mineral interference free spectra with in general least affected organic bands. Thus, HF treatment of soil offers a potential pre-treatment method for improved spectroscopic characterisation of soil organic matter. [ABSTRACT FROM AUTHOR]

Algae are known for high ash content. It is important to properly characterize their ash for value added utilization of algae as food, feed, and feedstock for biofuels. In this study, 12 algae of different sources were measured for proximate composition and mineral profile. Results showed that the relative difference between ash content by dry ashing and total minerals content by wet digestion increased with ash content. A major cause was soon identified: when using a common procedure of strong attacks for sample digestion before mineral analysis, incomplete digestion existed for most algae samples due to the presence of siliceous materials. It was proposed that algae consist of wet acid indigestible ash (WAIA) and wet acid digestible ash, whereas WAIA is siliceous. Methods to measure WAIA content in the 12 algae, along with oat grain, oat forage, defatted soymeal and fine sand, were then developed based on digestion with nitric acid or sulfuric acid-hydrogen peroxide. For the 12 algae, ash ranged 1.9 to 37.4% dry matter while WAIA by nitric acid digestion varied 0.1% to 25.6%. High correlation between WAIA and ash contents indicates WAIA as an important contributor for algae ash. For identifying what constituted the siliceous materials, all samples in three matrixes (original, ash by dry ashing, and WAIA) were microscopically examined. Because wet acid digestion had an ability to concentrate siliceous materials and maintain their original shape and size, WAIA was the best matrix for microscopic examination. Micrographs of WAIA show three types of siliceous materials in algae: non-diatom cellular structures, diatom cell walls, and sandy particles. It was concluded that high ash content of algae resulted partly from contamination of diatoms and/or sandy particles of geologic origin and that WAIA should be an important quality parameter for algae. Subsequently, several measures are proposed to produce algae with low ash content. [ABSTRACT FROM AUTHOR]

Purpose: To determine the elements in Bryonia alba L. roots, collected from the Crimean Peninsula region in Ukraine. Methods: Dry ashing was used as a flexible method and all elements were determined using atomic absorption spectrometry (AAS) equipped with flame and graphite furnace. Results: The average concentrations of the determined elements, expressed as mg/100 g dry weight of the sample, were as follow: 13.000 for Fe, 78.000 for Si, 88.000 for P, 7.800 for Al, 0.130 for Mn, 105.000 for Mg, 0.030 for Pb, 0.052 for Ni, 0.030 for Mo, 210.000 for Ca, 0.130 for Cu, 5.200 for Zn, 13.000 for Na, 1170.000 for K, 0.780 for Sr, 0.030 for Co, 0.010 for Cd, 0.010 for As, and 0.010 for Hg. Toxic elements such as Cd and Pb were also found but at very low concentration. Among the analyzed elements, K was the most abundant followed by Ca, Mg, P, Si, Fe, Na, and Zn, whereas Hg, As, Cd, Co, Mo, and Pb were found in low concentration. Conclusion: The results suggest that the roots of Bryonia alba L. plant has potential medicinal property through their high element contents present. Moreover, it showed that the AAS method is a simple, fast, and reliable for the determination of elements in plant materials. The obtained results of the current study provide justification for the usage of such fruit in daily diet for nutrition and for medicinal usage in the treatment of various diseases. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to determine the levels of cadmium (Cd), chromium (Cr), lead (Pb), arsenic (As) and selenium (Se) in (1) fresh tea leaves, (2) processed (black) tea leaves and (3) soils from tea plantations originating from Bangladesh. Methods: Graphite furnace atomic absorption spectrometry (GF-AAS) was used to evaluate six digestion methods, (1) nitric acid, (2) nitric acid overnight, (3) nitric acid-hydrogen peroxide, (4) nitric-perchloric acid, (5) sulfuric acid, and (6) dry ashing, to determine the most suitable digestion method for the determination of heavy metals in the samples. Results: The concentration ranges of Cd, Pb, As and Se in fresh tea leaves were from 0.03-0.13, 0.19-2.06 and 0.47-1.31 µg/g, respectively while processed tea contained heavy metals at different concentrations: Cd (0.04-0.16 µg/g), Cr (0.45-10.73 µg/g), Pb (0.07-1.03 µg/g), As (0.89-1.90 µg/g) and Se (0.21-10.79 µg/g). Moreover, the soil samples of tea plantations also showed a wide range of concentrations: Cd (0.11-0.45 µg/g), Pb (2.80-66.54 µg/g), As (0.78-4.49 µg/g), and Se content (0.03-0.99 µg/g). Method no. 2 provided sufficient time to digest the tea matrix and was the most efficient method for recovering Cd, Cr, Pb, As and Se. Methods 1 and 3 were also acceptable and can be relatively inexpensive, easy and fast. The heavy metal transfer factors in the investigated soil/tea samples decreased as follows: Cd > As > Se > Pb. Conclusion: Overall, the present study gives current insights into the heavy metal levels both in soils and teas commonly consumed in Bangladesh. [ABSTRACT FROM AUTHOR]

Pitch is a complex matrix and hard to be digested. In this way, some sample preparation methods (wet digestion and combustion) were investigated for subsequent determination of Ba, Ca, Cd, Fe, Mg, Pb, Sr, V and Zn using plasma-based techniques as well as direct analysis by X-ray fluorescence (XRF). Among the investigated sample preparation methods, dry ashing and microwave-induced combustion (MIC) shown similar results for some analytes, but significant losses for Cd, Pb and Zn were observed when dry ashing was used. Thus, MIC was chosen once a diluted solution (3 mol L −1 HNO 3 ) was suitable for analytes absorption, up to 400 mg of pitch could be digested and no analyte losses were observed. Accuracy of MIC was evaluated by analysis of a standard reference material of Green Petroleum Coke (NIST 2718). In addition, a comparison with results obtained by XRF and MIC was performed and no statistical difference was observed. Thus, the proposed MIC method can be considered as suitable for the digestion and further elements determination in pitch. [ABSTRACT FROM AUTHOR]

The goal of the present study was to establish the best procedure for the extraction of metals from medicinal plants. Wet ashing, dry ashing, and microwave digestion methods were applied with different mixtures of nitric and hydrochloric acids usingMalva sylvestris L.andPistacia lentiscusleaves collected from two sites in Algeria. Cadmium, chromium, copper, lead, and zinc were determined by atomic absorption spectrometry. There were significant differences in the metal concentrations extracted by the methods. The highest efficiency from the leaves were obtained using a dry ashing method using 4:1 HNO3:HCl (v:v), and this approach was considered to be the optimum procedure. However, the wet and microwave digestion methods were suitable for this extraction but with reduced digestion efficiency. The extraction method has a significant influence on the measured metal concentrations, which emphasizes the need to choose the optimum procedure. [ABSTRACT FROM PUBLISHER]

This work presents an overview of the development of dry ashing preparation techniques for solid and quasisolid sample analysis by atomic and inorganic mass spectrometry, including flame/graphite furnace atomic absorption spectrometry, chemical vapor generation atomic absorption/fluorescence spectrometry, and inductively coupled plasma–optical emission/mass spectrometry. This article also summarizes all of the dry ashing methods reported in the past 20 years. The dry ashing methods applied to sample preparation are classified as electrothermal ashing, microwave ashing, oxygen combustion, and other special ashing methods including laser, ultraviolet (UV)/ozone, and plasma. Moreover, the development of relevant devices is discussed in context. [ABSTRACT FROM PUBLISHER]

A sample pretreatment procedure for the dry radioactive waste such as paper, cotton, vinyl, and plastic generated from nuclear power plants (NPPs) was established to determine the activity concentrations of Co and Cs. Because the volatility of cesium is temperature-dependent, the heating temperature was examined from 300 to 650 °C. Although the cesium was not volatile until 500, 450 °C was selected to save time. Cesium with a paper towel and a planchet of stainless steel were quantitatively recovered at 450 °C. The produced ash was completely dissolved with 10 mL of HNO, 4 mL of HCl, and 0.25 mL of HF in a high-performance microwave digestion system using a nova high temperature rotor at 250 °C for 90 min until 0.2 g was reached. This procedure was applied to low and intermediate level radioactive wastes generated from NPPs. [ABSTRACT FROM AUTHOR]

There is a need to monitor the body burden of fluoride (F) in endemic areas without resorting to bone biopsy. For a biomarker of F exposure to be applicable in a large population, it should be easily collectible without objections from the donors and be an effective, a reliable, and a valid method of F estimation. The present study was designed as a population based observational cross-sectional study. The F content in toe nail clippings was determined by the dry ashing method in a total of 40 local residents residing in three F endemic areas of the Jaipur district of Rajasthan, India, with mean drinking water F levels of 4.1, 4.8, and 5.6 ppm. The F levels of serum and 24 hr urine were also estimated in the same population. The mean nail ash F levels were extremely high with a range of 82.38±6.89 - 103.92±16.89 ppm. Highly significant relationships were present between the water F levels and the F levels in toe nail (p<0.001), serum (p<0.001), and urine (p<0.001). Similarly, significant relationships were present between the toe nail F levels and the F levels in serum (p<0.001 and p<0.01) and urine (p<0.001 and p<0.01). The presence of F in toe nail indicates that F is obtained from the systemic circulation to the nail beds and deposited in the nails by either continuous incorporation or secondary concentration. Toe nail F is a useful biomarker for both subchronic and chronic F exposure. [ABSTRACT FROM AUTHOR]

Rice is a Si-accumulator plant, whereby Si has physio-chemical functions for plant growth. Its straw contains high shares of plant silica bodies, so-called phytoliths, and can, when returned to the soil, be an important Si fertilizer. Release of Si from phytoliths into soil solution depends on many factors. In order to improve prognosis of availability and management of Si located in phytoliths, in this study we analyzed the effect of pretreatment of rice straw by dry and wet ashing and the soil-solution composition on Si release. Dry ashing of rice straw was performed at 400°C, 600°C, and 800°C and wet ashing of the original straw and the sample from 400°C treatment with H2O2. To identify the impact of soil-solution chemistry, Si release was measured on separated phytoliths in batch experiments at pH 2-10 and in presence of different cations (Na+, K+, Mg2+, Ca2+, Al3+) and anions (Cl-, NO $ _3^- $, SO $ _4^{2-} $, acetate, oxalate, citrate) in the concentration range from 0.1 to 10 mmolc L-1. After burning rice straw at 400°C, phytoliths and biochar were major compounds in the ash. At an electrolyte background of 0.01 molc L-1, Si released at pH 6.5 was one order of magnitude higher than at pH 3, where the zeta potential (ζ) was close to zero. Higher ionic strength tended to suppress Si release. The presence of cations increased ζ, indicating the neutralization of deprotonated Si-O- sites. Monovalent cations suppressed Si release more strongly than bivalent ones. Neutralization of deprotonated Si-O- sites by cations might accelerate polymerization, leading to smaller Si release in comparison with absences of electrolytes. Addition of Al3+ resulted in charge reversal, indicating a very strong adsorption of Al3+, and it is likely that Si-O-Al-O-Si bonds are formed which decrease Si release. The negative effect of anions on Si release in comparison with deionized H2O might be due to an increase in ionic strength. The effect was more pronounced for organic anions than for inorganic ones. Burning of rice straw at low temperatures ( e.g., 400°C) appears suitable to provide silicon for rice in short term for the next growing season. High inputs of electrolytes with irrigation water and low pH with concomitant increase of Al3+ in soil solution should be avoided in order to keep dissolution rate of phytoliths at an appropriate level. [ABSTRACT FROM AUTHOR]

Abstract: Phytolith research on foxtail and common millets represent one of the keys to explore early agricultural activities in the Yellow River basin in China. However, the phytoliths of these two millets easily disintegrate during burial and the extraction process. In this paper, both dry ashing and wet oxidation methods were applied to determine the effects on phytolith extraction from archaeological soil samples. The results indicated that the dry ashing method had two significant advantages over wet oxidation: (1) the morphology of husk phytoliths was retained to a greater extent; and (2) nearly all the charcoalified tissues were removed successfully. The dry ashing method proved to be a better method for phytolith extraction of both foxtail millet as well as common millet from archaeological samples. [Copyright &y& Elsevier]

Silica phytoliths are a subgroup of biogenic opal. Silica phytoliths are formed in many plant species and remain preserved in soil and sediments after plant decay. The chemical composition of fossil phytoliths may reveal ancient plant taxa, soil composition and climate. However, actually detailed knowledge on silica phytolith composition is scarce. Here we present result of instrumental neutron activation analysis of barley awns, stems and leaves, and barley phytoliths. The elements of interest were Na, Mg, Al, Si, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Br, Rb, Sb, Cs, Ba, La, Ce, Sm, Eu, Tb, Dy, Yb, Hf, Ta, W, Th, and U. We compared three phytolith extraction methods: dry ashing, acid digestion, and acid digestion followed by incineration. We found that sole acid digestion is inefficient to remove organic matter. By contrast both dry ashing and acid digestion followed by incineration are suitable for phytolith analysis. Comparison of phytoliths with their source plant material shows that phytoliths are enriched in terrigenous elements such as Al, Sc, Ti, V, Cs, Fe, rare earth elements, and depleted in the major inorganic constituents of plants such as K, Ca, Mg, Mn, Cl and Br. [ABSTRACT FROM AUTHOR]

Experiments were conducted to determine the effects that different methods for the preparation of modern plant samples have on the resulting phytoliths using rice husks ( Oryza sp.). The methods that are commonly used in phytolith extraction include (1) dry ashing, (2) acid extraction (3) a combination of both techniques. The results showed that processing methods have an impact on the morphology of two subspecies of rice phytoliths, dry ashing producing more conjoined cell phytoliths or multicells phytoliths than acid extraction. Using a combination of both methods resulted in the presence of fewer conjoined cells than dry ashing alone, but more conjoined cells than acid extraction. Alternative explanations are proposed to explain the formation of conjoined phytolith cells. Microsc. Res. Tech. 75:1272-1276, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was used to investigate the level of trace metals (Ba, Pb, Cd, Mn, Cr, Co, Ni, Cu, Mn, Zn, Sr and Fe) in some dried fruits (Prunus domestica L., Ficus carica L., Morus alba L., Vitis vinifera L., Prunus armeniaca L., and Malus domestica) samples from Turkey. Trace elements were determined by ICP-OES after dry, wet and microwave digestion methods in dried fruit samples. Validation of the proposed method was carried out by using a NIST-SRM 1515-Apple Leaves certified reference material. Element concentrations in dried fruit samples were 0.33–1.77 (Ba), 0.12–0.54 (Cd), 0.25–1.03 (Co), 0.45–2.30 (Cr), 0.43–2.74 (Cu), 0.56–4.87 (Mn), 0.61–2.54 (Ni), 0.40–2.14 (Pb), 2.16–6.54 (Zn), 0.83–12.02 (Al), 11.82–40.80 (Fe) and 0.16–6.34 (Sr) μg/g. The analytical parameters show that the microwave oven digestion procedure provided best results as compared to the wet and dry digestion procedures. The results were compared with the literature values. [Copyright &y& Elsevier]

Most investigations on heavy metals content in fish were either conducted on single markets, ports, seaside markets or direct sampling from natural habitat, and there were very few studies done on fish samples from both wet markets and supermarkets. This paper presents the assessment outcome of Cd and Pb levels in commercial fish sold between wet markets and supermarkets in Klang Valley, Malaysia. In this study, the organs of four commercial fish species (Rastrellinger kanagurta, Epinephelus sexfasciatus, Lates calcarifer, and Decapterus maruadsi) sampled from different markets within the sampling area were assessed using dry ashing-acid digestion method and Flame AAS. Results obtained concluded that Cd and Pb in fishes sampled from supermarkets are generally higher compared to wet markets, while both metals content in the edible organs fall well within the permissible limits for human consumption when compared to the Fourteenth Schedule of the Malaysian Food Regulations 1985. [ABSTRACT FROM AUTHOR]

Abstract: The concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, Se and Zn in cheese samples packaged in plastic and tin containers were analyzed using inductively coupled plasma-optical emission spectrometry after microwave, wet and dry digestion processes. In order to evaluate the best digestion method, the relationships between the concentrations of trace metals in cheese samples after microwave digestion was compared by wet and dry ashings. Microwave digestion was found fast, reliable, simple, and excellent procedure in comparison with dry and wet ashing methods. The accuracy of the digestion procedures was determined by using standard reference material (GBW 07605-Tea). The order of levels of the elements in the white cheese samples packaged in tin containers was determined to be Cd

Abstract: As, Sb, Se, Te and Bi were quantified in vegetables, pulses and cereals, in order to increase the available information on the presence of these elements in the Mediterranean daily intake. Samples were dry ashed and the ashes dissolved with diluted HCl. Hydride generation atomic fluorescence spectrometry was used for quantification. Limits of detection (LOD) ranged from 0.2 to 1.7ngg−1 and the accuracy was assessed by the analysis of three certified reference materials, Rice Flour (NIST 1568a), Tomato Leaves (NIST 1573) and Cabbage (IAEA 359). Good concordance between results found and certified values were always observed. As, Sb, Se, Te and Bi levels varied in samples analysed from values under the LOD till 1001, 47, 270, 104 and 48ngg−1, respectively. [Copyright &y& Elsevier]

Abstract: Elements, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, and Sr in bee honey samples were determined using an improved dry ashing (DA) method for XRF with Mo-secondary target (Mo-XRF). The sensitivity of the DA method was significantly improved in comparison to the wet ashing (WA) and the direct (D) methods. The limits of detection (LODs) obtained by DA (3.4–0.007µg/g) method were better by an order of magnitude than those obtained by WA (34.0–0.120µg/g) and D (61.2–0.270µg/g) methods. Further improvements in the sensitivity of the DA-XRF were achieved by using a Cu-secondary target for the excitation of the elements of K, Ca, Ti, Cr, and Mn. In this instance, the LODs were in the range of 0.220–0.024µg/g. The results of DA-XRF analysis revealed a very good accuracy with errors less than 7.1% and a precision with a relative standard deviation (RSD) better than ±8.8%. The improved DA-XRF analysis was applied for the determination of the above mentioned elements in several Syrian bee honey samples. The results were comparable to those obtained by the atomic spectrometry method with correlation coefficients better than 0.9927. [Copyright &y& Elsevier]

Abstract: Durum wheat plants grown under optimum irrigation conditions in Jordan were processed in three different ways: 1) using a dry ashing method, 2) using acid extraction and 3) using both these methods, first dry ashing and then acid extraction. The aim was to determine if the laboratory processing method employed has an impact on the number of conjoined phytoliths recovered. This is important because it has been proposed that the number of conjoined phytoliths, or multi cells, can be an indication of water availability in arid and semi-arid regions (Rosen and Weiner 1994). The results showed that the processing method does have an impact on the resulting assemblage, with dry ashing producing a greater number of multi-cells than acid extraction. It is proposed that either the more violent oxidation of organic matter during acid extraction causes the breakup of conjoined phytoliths, or that the silica dehydrates during dry ashing resulting in a slight fusion between the individual phytoliths and hence more conjoined forms. [Copyright &y& Elsevier]

In the present study, the determination of mineral and trace elements (Al, B, Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) from pine needles using three sample pre-treatment methods followed by inductively coupled plasma optical emission spectrometry, was examined. Sample pre-treatment methods tested were microwave digestion, ultrasound-assisted digestion and dry ashing. The new ultrasound-assisted digestion method was optimised by the analysis of the standard reference material (SRM) 1575a (pine needles) sample. The speed of dry ashing method was significantly increased by ultrasound dissolution after ashing. All the ICP-OES measurements were performed in robust plasma conditions which were tested by measuring the Mg II 280.270 nm/Mg I 285.213 nm line intensity ratios. The microwave digestion resulted generally in slightly higher element concentrations than ultrasound-assisted digestion. B, Cu and Na resulted in such low concentrations that they could not be accurately determined by using the microwave digestion method. The t-tests found no significant differences between the certified and the determined element concentrations of the SRM 1575a using the dry ashing method followed with ultrasound dissolution. [ABSTRACT FROM AUTHOR]

Abstract: The levels of trace elements in different types of food material consumed in Turkey were determined by flame and graphite furnace atomic absorption spectrometry. Food samples were digested with dry ashing, wet ashing and microwave digestion procedures in this study. The microwave digestion procedure was chosen for the digestion of all the food samples because it required shorter time and made higher recovery (specially for Se). Fe, Cu, Mn, Zn, Al and Se were determined by flame and graphite furnace atomic absorption spectrometry, respectively. Relative standard deviations (RSD) were found below 10%. The accuracy of the procedure was confirmed by certified reference materials. Moreover, this procedure was easier to use when compared with dry and wet digestions. [Copyright &y& Elsevier]

Abstract: In this paper, a screening approach, involving the use of the Plackett–Burman experimental design, permitted the evaluation of the effects of 25 parameters from the sample pretreatment stage (furnace heating temperature, furnace heating duration, cooling, filtration, addition of HCl…) on the Pb, Cr and Al determination in macroalgae by graphite furnace atomic absorption spectrometry (GF-AAS). According to the found results, the influences of the different factors depend on the selected metal. Nevertheless, addition of the concentrated acids HF and HCl enhanced the analytical signals of all the metals. The effects of some parameters, such as filtration or cooling of samples, were negligible. These factors could be eliminated from the pretreatment stage to gain cost and time. The obtained results allowed the proposition of a method for the pretreatment of algae. This method was validated against BCR-CRM 279 sea lettuce (Ulva lactuca). [Copyright &y& Elsevier]

Abstract: The main purposes of the study presented in this paper are to select the optimal temperature of dry ashing and to carry out posterior analyses of elements in the ash formed. The concentration of elements from biomass was compared with the concentration of elements in ash obtained at 400, 500, 550, 600 and 800°C, utilising four woody and herbaceous biomasses: pine chips, poplar chips, thistle and wheat straw. A dry ashing temperature in the 500–550°C range was found to produce ashes low in organic carbon (less than 1wt%) and to recover the greatest amount of the element contents present in the original biomass. A slight loss of potassium and sodium is determined in the ashes produced at temperatures as low as 400°C for herbaceous biomass compared with the potassium and sodium analysed in biomass. [Copyright &y& Elsevier]