Wet Ashing Research Articles

Levels of essential and toxic metals in fenugreek seeds (Trigonella Foenum-Graecum L.) cultivated in different parts of Ethiopia

Summary The levels of the major (Ca, K, Na, Mg), trace (Fe, Cr, Ni, Zn, Mn, Cu, Co), and toxic (Pb, Cd) metals in the seeds of fenugreek cultivated in different regions of Ethiopia were determined by flame atomic absorption spectrophotometry (FAAS). Wet ashing was used to digest 0.5 g of fenugreek seed flour using 1.5 mL of HNO3 and HClO4 acid mixtures (5:1 ratio), 30 min pre-digestion time, 45 min total digestion time and a temperature of 150 °C. Thirteen elements were determined, obtaining concentrations in the following ranges: Ca (15353-36771 mg kg-1) > Fe (6041-18584 mg kg-1) ≈ K (6789-11517 mg kg-1) > Pb (615-2624 mg kg-1) > Na (201-1559 mg kg-1) > Cd (285-464 mg kg-1) > Cr (3-552 mg kg-1) > Ni (31-108 mg kg-1) > Mg (31-102 mg kg-1) > Zn (15-33 mg kg-1) > Mn (16-28 mg kg-1) > Cu (ND-35 mg kg-1) > Co (4-15 mg kg-1). A statistical analysis of variance (ANOVA) at the 95% confidence level revealed there were significant differences between the mean metal contents of fourteen sample means, except for Zn. Pearson’s correlation revealed weak positive or negative linear relationships, which implies that the presence of one metal did not affect the presence of the other metals within the plant, except for a few metals. The study showed that fenugreek seeds were a good source of essential metals. However, they also contained large amounts of the toxic metals Cd and Pb and therefore should not be consumed daily.

Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products.

Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

Thermodynamic and kinetic study of CaS in aqueous systems

One of the main sources of sulfide in fuel combustion ashes is the hazardous compound calcium sulfide (CaS), which decomposes in water and releases sulfide compounds into the environment. In order to safely use hydrotransport and open air deposition of wet ash, as well as to treat alkaline ash transportation waters, it is important to know the dissolution behavior of CaS, in this regard, several values of both CaS solubility and equilibrium constants of dissolution reactions are illustrated in the scientific literature. To reconcile these differences, both kinetics and equilibrium of CaS dissolution reactions under inert and air conditions at 25°C were studied. The water solubility of CaS under an inert atmosphere (with N2 treated water) is lower (2.29·10−3mol/L) than under air (2.74·10−3mol/L). A more complex reaction mechanism for open air dissolution, elucidated using HsC Chemistry® 7.1 simulations, was also presented. Various reaction mechanisms as well as equilibrium and rate constants were evaluated to model CaS dissolution data. The relatively small deviations between calculated values and experimental data confirm that the suggested models could be employed to describe CaS dissolution under both atmospheric and inert conditions.

Accelerating wet torrefaction rate and ash removal by carbon dioxide addition

In this study, CO2 was employed as an environment friendly catalyst for wet torrefaction of fresh Norwegian forest residues. The effects of CO2 addition on the yield and the properties of hydrochar were experimentally studied and compared with the base case, wet torrefaction in N2. The results showed that wet torrefaction in CO2 and N2 has similar effects on the improvement in the fuel properties of biomass. However, CO2 was found to improve the reactivity of forest residues during wet torrefaction, producing the same hydrochar yield at less severe conditions compared with N2. The hydrochars produced in CO2 had lower heating value and energy yield, but better grindability and hydrophobicity, compared with those in N2. More importantly, CO2-enriched wet torrefaction can remove up to 60–69% of the ash content in the forest residues, compared to only 14–26% for wet torrefaction in N2.

Gross actinide preconcentration using phosphonate-based ligand and cloud point extraction

A procedure for the effective separation and determination of the most abundant actinides relevant to the nuclear industry (U, Th, Np, Pu and Am) was developed based on cloud point extraction (CPE) using H2DEH[MDP] (P,P-di-(2-ethylhexyl) methanediphosphonic acid) as a ligand. The extractability of actinides with varying concentrations of nitric acid and hydrochloric acid were assessed. The robustness of the method was demonstrated for environmental matrices such as reference materials and spiked liquid samples for the quantification of the gross actinide content. This analytical strategy may replace traditional sample preparation techniques used in radiological methods for gross measurements of radioactivity, and may act as a rapid screening tool in emergency situations. The developed method is a greener alternative to common radiochemical sample preparation techniques such as co-precipitation or evaporation. The formation of a small-volume surfactant-rich phase containing the complexed actinides enables rapid, highly selective and great enrichment of the analytes in this phase. The proposed method shows good extraction and separation yield compared to existing methods, since the surfactant-rich phase is soluble in water and can therefore be redispersed quantitatively in a medium compatible with mass spectrometry while providing fast isolation of the actinide content. Separation of actinides can be achieved after by wet ashing of the surfactant-rich phase obtained by CPE if coupled to the proper radiochemical separation scheme.

Impact of the uranium (VI) speciation in mineralised urines on its extraction by calix[6]arene bearing hydroxamic groups used in chromatography columns

Actinides determination in urine samples is part of the analyses performed to monitor internal contamination in case of an accident or a terrorist attack involving nuclear matter. Mineralisation is the first step of any of these analyses. It aims at reducing the sample volume and at destroying all organic compounds present. The mineralisation protocol is usually based on a wet ashing step, followed by actinides co-precipitation and a furnace ashing step, before redissolution and the quantification of the actinides by the appropriate techniques. Amongst the existing methods to perform the actinides co-precipitation, alkali-earth (typically calcium) precipitation is widely used. In the present work, the extraction of uranium(VI), plutonium(IV) and americium(III) from the redissolution solutions (called “mineralised urines”) on calix[6]arene columns bearing hydroxamic groups was investigated as such an extraction is a necessary step before their determination by ICP–MS or alpha spectrometry. Difficulties were encountered in the transfer of uranium(VI) from raw to mineralised urines, with yield of transfer ranging between 0% and 85%, compared to about 90% for Pu and Am, depending on the starting raw urines. To understand the origin of such a difficulty, the speciation of uranium (VI) in mineralised urines was investigated by computer simulation using the MEDUSA software and the associated HYDRA database, compiled with recently published data. These calculations showed that the presence of phosphates in the “mineralised urines” leads to the formation of strong uranyl-phosphate complexes (such as UO2HPO4) which compete with the uranium (VI) extraction by the calix[6]arene bearing hydroxamic groups. The extraction constant of uranium (VI) by calix[6]arene bearing hydroxamic groups was determined in a 0.04molL−1 sodium nitrate solution (logK=4.86±0.03) and implemented in an extraction model taking into account the speciation in the aqueous phase. This model allowed to simulate satisfactorily the experimental uranium extraction data and to support the preliminary conclusions about the role of the phosphates present in mineralised urines. These calculations also showed that the phosphate/calcium ratio is a key parameter as far as the efficiency of the uranium (VI) extraction by the calix[6]arene columns is concerned. It predicted that the addition of CaCl2 in mineralised urines would release uranium (VI) from phosphates by forming calcium (II)-phosphate complexes and thus facilitate the uranium (VI) extraction on calix[6]arene columns. These predictions were confirmed experimentally as the addition of 0.1molL−1 CaCl2 to a mineralised urine containing naturally a high concentration of phosphate (typically 0.04molL−1) significantly increased the percentage of uranium (VI) extraction on the calix[6]arene columns.

Quantitative Determination of The Heavy Metals (Lead, Zinc And Manganese) in White Cheese Produced in Ergene Basin by Using Atomic Absorption Spectrophotometry

SUMMARY It is well known that heavy metals are harmful for human health appearing only after exceeding the specific concentrations of each metal. This study was carried out to determine the concentrations of heavy metals in cheese that was produced in diaries of Ergene Basin. The dairies near the Ergene River were investigated and suitable ones were selected. Since the sampling process directly affects the sensitivity of the results, particular attention was given to this process. A total of twelve samples of cheese were collected from different diaries and each samples were digested three times by dry ashing and wet ashing methods and totally 108 cheese samples were obtained for metal analyses. The lead, manganese content of the cheese samples were measured by graphite furnace atomic absorption spectrophotometer and zinc content of the cheese samples were measured by flame atomic absorption spectrophotometer. Contents of heavy metals in the examined samples were compared with the excepted limit values in the literature and the results were evaluated. Experimental data shows that the concentrations of heavy metals are in the range of accepted limit values. Key words : Cheese, Ergene Basin, Atomic Absorption Spectrophotometry, Heavy Metals

New technology and application of brick making with coal fly ash

China has ranked first in the coal fly ash emission in the world. The multipurpose use of the fly ash from power plant waste is always an important topic for the Chinese environmental protection, which has drawn the concern of the government, scientific research departments, manufacturing enterprises and industry experts. This paper introduces an experimental research on how to recycle fly ash effectively, a kind of new technology of making bricks by which fly ash content could be amounted to 50–80 %. The article introduces raw materials of fly ash brick, production process and key control points. It introduces how to change the technical parameters of the existing brick-making mechanical device, optimize the parameters combination and improve the device performance. High-content fly ash bricks are manufactured, which selects wet fly ash from power plants, adding aggregate with reasonable ratio and additives with reasonable dosage, and do the experimental research on manufactured products for properties, production technology and selection about technology parameters of production equipment. All indexes of strength grade, freezing-thawing resisting, and other standards of the studied bricks reached the national standards for building materials industry.

Evaluation on the applicability of dry processed bottom ash as lightweight aggregate for construction fields

Currently, wet bottom ash is not sufficiently utilized due to its content of unburned coal, chloride and moisture. In contrast, bottom ash discharged from the recently introduced dry process spends a longer time on the clinker conveyer in the lower part of the boiler and consequently contains a significantly smaller amount of unburned coal. Consequently, it has high potential for use as a lightweight aggregate for construction material because of properties such as high porosity, low unburned coal content, non-chloride, and non-moisture. However, it is not frequently used for construction because the ash particle has a flat and thin shape, coarse surface and unfavorable structural strength. Against this backdrop, this study has conducted a range of experiments to identify the shapes, structure, density, absorption, percentage of floating particles, unit volume weight, solid volume, characteristics of air bubbles and micro pores, crushing strength of bottom ash, and the following results were observed. Though the dry bottom ash has sharp and angular edges, its flat and thin shapes lead to vulnerable structures. Dry bottom ash of the size of 0.6 mm or larger has 50–60 % of the total pore rate and 30–50 % of the closed pore rate. Considering these qualities, by removing the relatively fragile surface parts and making the particles more globular, dry bottom ash can be used as a lightweight aggregate for construction field having outstanding performance in terms of light weight and insulation.

Optimization of Extraction of Toxic Metals from Medicinal Plants, Malva sylvestris L., and Pistacia lentiscus

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 using Malva sylvestris L. and Pistacia lentiscus leaves 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.

Minerals Profile of Soil, Feed, Fodder and Serum of Dairy Cattle in North Eastern Ghat (NEG) of Odisha

A survey based study was planned in North Eastern Ghat (NEG) of Odisha to analyse the mineral profile of soil, feed, fodder and serum of dairy cattle. This agro-climatic zone comprises of four districts namely Kandhamal, Ganjam, Raygada and Gajapati. Amongst those two districts viz Ganjam and Gajapati are taken for the study considering the density of dairy cattle population. In the similar manner two Blocks from Ganjam District namely Khallikote, Kukudakhandi and two blocks from Gajapati District namely Mohana, R.Udayagiri was considered for our experimental area with two villages from each of the block. Macro and micro minerals like Calcium (Ca), Phosphorus (P), Zinc (Zn), Copper (Cu), Manganese (Mn) and Iron (Fe) were estimated for soil, feed, fodder and serum. Soil Ca was estimated by rapid titration method and available soil phosphorus was determined by colorimetric analysis. The soil micro minerals like Cu, Fe, Zn and Mn were analyzed as per the method of Lindsay and Lindsay (1978). Dry ash and Wet ash method were used for analysis of macro and micro minerals respectively for feed and fodder. The concentration of Ca and P in serum was estimated by using the kit method. The serum micro minerals like Cu, Fe, Zn and Mn were estimated by Atomic Absorption Spectrophotometer method. The findings depicted that cattle of this region are severely deficient in Ca, Zn, and Cu and marginally deficient in P and Mn with higher value of Fe content than the respective critical levels. Considering the importance of productivity and reproductive performance of dairy animal an area specific mineral mixture must be prepared and fed to the animals to meet the deficiencies of these minerals.

Arsenic Intake through Consumed Rice in Iran: Markets Role or Government Responsibility.

the present study investigated arsenic content in Iranian, imported rice on sale in Tabriz (fourth most populous city of Iran) market, and assesses daily arsenic intake from rice. A total of 33 locally available rice samples from different brands were collected and then wet and dry ashing digestion procedures were compared for decomposition of them before analyzing by graphite furnace atomic absorption spectrometry (GFAAS). The mean arsenic concentration in Iranian rice was 0.065 mg/kg versus 0.082 mg/kg in imported samples. There was no significant difference between arsenic concentrations between two groups of samples (P=0.061). The average daily ingestion rate of total arsenic was 0.11 and 0.15 μg/kg body weight from consumption of 110g of Iranian and imported rice respectively. Based on our estimation, daily dietary intake of arsenic from Iranian and imported rice was approximately 7 and 9 μg/day for local population, respectively.All of the rice grains that were sampled from Tabriz market were low in total arsenic compared to the standard. Nonetheless regular monitoring of all rice varieties should be continued.

An Evaluation of PCDD/Fs Mass Flux from a Hazardous Waste Incinerator: The Need for a Reasonable Start-Up Procedure

The study includes an investigation on the polychlorinated dibenzo-p-dioxins (PCDD/Fs) mass fluxes of a hazardous waste incinerator in the operation conditions, which occurred shortly after two different start-up periods. The samples were taken from seven possible dioxin output points through the incineration and air pollution control units, which include bottom ash, boiler fly ash, electrostatic precipitator (ESP) fly ash, treated wastewaters and filter cake from the physicochemical treatment of dual wet scrubbers and fly ashes, activated carbon (AC) bed, and stack gas, and they were analyzed for the PCDD/Fs. The results were assessed to determine the emission factors and the mass fluxes of PCDD/Fs for all of the outputs. A review of the congener profiles suggested that start-up conditions, such as the start-up duration and the cleaning process, may have an effect on the concentrations and congener profiles of PCDD/Fs, especially observed in the fly ashes and the stack gas. Considerable concentrations of low chlorinated furans in the ash outflows were attributed to the heterogeneous de novo synthesis of PCDD/Fs on the fly ash surfaces. Congener contributions to the mass flux of each outflow showed that the congeners retained in bottom ash are generally highly chlorinated ones, while the congeners retained by AC bed or released to the atmosphere are predominately low chlorinated ones. The results indicated that a short and clean start-up procedure in terms of a reasonable emission factor in the stack may be needed.

Effect of Solid Fuel Mineral Composition on the Formation of Sour Pulp in Hydro-Slug Removal System of Thermal Power Plants

<p>Researches have been conducted into the causes of acidity of pulp formed in the system of circulating hydraulic ash and slag removal in thermal power plants (TPP) when using coals of Ekibastuz and Karaganda coal fields of the Republic of Kazakhstan. We have carried out a comparative study of combustion of Karazhyra and Maikube coals at the two RK TPPs with BKZ-75-39FB and BKZ-160-100FB steam boilers. For ash collection, wet ash collectors with remounted Venturi tube coagulators have been installed on TPP. In them, a chemical interaction of irrigating water with flue gases occurs, which include CO<sub>2</sub>, SO<sub>2</sub>, SO<sub>3</sub> and ash particles. The ash pulp formed moves to the pipeline, mixes with the slag pulp and is further transported along a tract to the ash dump. We have defined the relationship between the composition of the products of coal combustion and the formation of acidic pulp in the scrubber. Qualitative and quantitative composition of coals and their combustion products have been determined by the methods of X-ray and X-ray fluorescence analysis. As the analysis showed, the main components of ash and slag materials are the oxides SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, CaO, MgO, K<sub>2</sub>О, Na<sub>2</sub>O. In the wet ash collectors gaseous substances present in flue gases, are dissolved and hydrolysed in irrigating water. While hydroremoving ash and slag, the compounds are dissolved in water and undergo hydrolysis. Oxides SiO<sub>2</sub>, SO<sub>2</sub>, TiO<sub>2</sub>, P<sub>2</sub>O<sub>5</sub> are hydrolyzed into acid, oxides CaO, MgO, K<sub>2</sub>O and Na<sub>2</sub>O – into base, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3 </sub>– into amphoteric compounds. Chemical analysis of ash and slag pulp formed after Karazhyra coal combustion has been carried out. Calculation of the acidity of ash and slag material has been performed. Karazhyra coal ash is more acidic in nature. A lower content of amphoteric oxides in Maikube coal appears to be the cause of the pulp formation, with a higher pH. With X-ray diffraction method, the nature of combinations of metal oxides in the samples of coal, slag and ash have been determined. </p>

Investigations into Phytoliths as Diagnostic Markers for the Grasses (Poaceae) of Punjab

Grasses are known to accumulate amorphous silica (SiO2.nH2O) within and between cells as silica bodies of characteristic shapes. The position and type of the host cells are the characters that seem to control their shape and size. The present study was carried out to assess and utilize the diagnostic potential of phytolith types in the identification of grass taxa at sub-familial, tribal, generic and specific levels. Clearing solution method was employed for locating the position of phytoliths within and between cells. Dry and wet ashing methods were subsequently employed for their isolation. Scanning Electron Microscopy was performed to study the ultra-structural features of phytoliths. Micromorphometric measurements of phytoliths were carried out with the help of image analysis software (Image J 1.46r). The study has brought out diagnostic potential of phytolith types for characterization of grasses of Punjab plains. For example, hat shaped phytoliths were identified as the diagnostic marker type for Digitaria ciliaris (Retz.) Koeler. However, full taxonomic potential of phytolith types for characterization of taxa can be realized only after further analysis of their physical properties and chemical architecture.

Evaluation of sample pretreatment methods for analysis of polonium isotopes in herbal medicines

Herbal infusions like ayurvedic aristas are widely consumed by Indian population for good health. With increasing awareness about radiological assessment, an effort was made to assess the radioactivity concentration of naturally occurring radionuclides in herbal medicines. 210Po is an important alpha particle emitter contributing to internal dose to man from ingestion. Though 210Po can be spontaneously deposited on silver disk for alpha spectrometric measurements with less radiochemical step, great care has to be taken during the sample pretreatment step owing to the high volatility of polonium even at low temperatures. Aim of the study was to evaluate an appropriate sample pretreatment method for estimation of polonium in herbal medicines. 209Po was used for radiochemical yield calculation. Conventional open vessel wet ashing, physical evaporation, freeze-drying and microwave digestion in a Teflon vessel were examined. The recovery ranged between 9 and 79%. The lowest recovery was obtained for the samples that were processed by open vessel digestion without any volume reduction. The recoveries were comparable for those samples that were freeze dried and subjected to HNO3 + HClO4 + H2O2 + HF acid digestion and microwave digested samples. 210Po concentration in the samples ranged from 11.3 to 39.6 mBq/L.

Stability and Broad-Sense Heritability of Mineral Content in Potato: Copper and Sulfur

Sulfur and copper are important for human health. Sulfur deficiency is rare, but may occur in the elderly. How- ever, a large percentage of the U.S. population is deficient in copper. The purpose of this study was to determine the range of values for sulfur and copper available in advanced potato germplasm and varieties and estimate how much genetic variation exists for these two elements. Potato breeding lines and varieties in three multisite trials were evaluated for copper and sulfur content by wet ashing and Inductively Coupled ArgonPlasmaEmissionSpectrophotometer analysis.Stability and broad-sense heritability were determined. Among geno- types, copper content ranged from 2.0 to 4.5 ug-g �1 DW. This was a 2.25-fold difference. In these three trials, environment was never significant, while genotype by environment inter- actions were always significant. Genotype was significant in two of the regional trials. Broad-sense heritabilities were estimated to be 0.0, 0.93 and 0.51 for the Tri-State, Western Regional Russet and Western Regional Red/Specialty trials, respectively. Among genotypes, sulfur content ranged from 991 to 1488 ug-g �1 DW. The highest value was 50 % higher than the lowest. In these three trials, environment was never significant, while genotype x environment interactions were always significant. Genotype was significant in two of the regional trials. Broad-sense heritabilities were estimated to be 0.53, 0.68 and 0.88, for Tri-State, Western Regional Russet, and Western Regional Red/Specialty trials, respectively. For both sulfur and copper, selection in the Western Regional Russet and Western Regional Red/Specialty trials is likely to lead to an increase in content. Selection for sulfur in the Tri- State would result in a gain as well. These results suggest that genetic improvements could be made to potato to enhance the concentrations of these minerals.

Detection of copper, lead, cadmium and iron in wine using electronic tongue sensor system

An array of 10 potentiometric chemical sensors has been applied to the detection of total Fe, Cu, Pb and Cd content in digested wine. As digestion of organic matter of wine is necessary prior to the trace metal detection using potentiometric sensors, sample preparation procedures have been optimized. Different variants of wet and microwave digestion and dry ashing, 14 conditions in total, have been tested. Decomposition of organic matter was assessed using Fourier transform mid-infrared spectroscopy and total phenolic content. Dry ashing was found to be the most effective method of wine digestion. Measurements with sensors in individual solutions of Fe(III), Cu(II), Pb(II) and Cd(II) prepared on different backgrounds have shown that their detection limits were below typical concentration levels of these metals in wines and, in the case of Cu, Pb and Cd below maximum allowed concentrations. Detection of Fe in digested wine samples was possible using discrete iron-sensitive sensors with chalcogenide glass membranes with RMSEP of 0.05mmolL−1 in the concentration range from 0.0786 to 0.472mmolL−1. Low concentration levels of Cu, Pb and Cd in wine and cross-sensitivity of respective sensors resulted in the non-linearity of their responses, requiring back-propagation neural network for the calibration. Calibration models have been calculated using measurements in the model mixed solutions containing all three metals and a set of digested wine sample. RMSEP values for Cu, Pb and Cd were 3.9, 39 and 1.2μmolL−1 in model solutions and 2, 150 and 1μmolL−1 in digested wine samples.

An extension to “Mid-infrared spectral interpretation of soils: Is it practical or accurate?”

This note extends the topic of the performance of ashing soil samples and then using spectral subtraction of diffuse reflectance Fourier transform mid-IR spectroscopy (DRIFTS) of original and ashed samples in highlighting the significance of the organic fraction. It was found that accurately interpreting the ash subtracted spectra (mid-infrared range from 4000cm−1 to 400cm−1) is nearly impossible not only because soil minerals undergo extreme spectral changes from the ashing process but also because inorganic residues from burning soil organic matter (mainly humic substances) also confound the spectra of the mineral fraction. Removing soil organic matter using wet ashing methods with H2O2, NaOCl, or Na2S2O8 is associated with inaccuracies in spectra interpretation from organic remains (uncompleted organic matter removal) and spectral changes of minerals from wet ashing processes. Accordingly, with the current techniques of dry and wet ashing it is impossible to accurately interpret the ash subtracted spectra of soil samples.

Elements analysis of infant milk formula by ICP-OES: a comparison of pretreatment methods

Sample pretreatments are critical steps for achieving true and precise results in element analysis for infant milk formula. In this study, we made a comparative study of four pretreatment methods: dry ashing (DA), wet ashing (WA), microwave ashing (MA) and slurry dispersion analysis. Nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) were determined by inductively coupled plasma optical emission spectrometry. Infant formula (GBW08509) with certified values was used for assessment of trueness and precision. The data showed that all relative standard deviations (RSD) of the observed values were <15 %. In contrast to other pretreatment, results for MA had the lowest RSD (≤5 %) for all the elements. For Cu and Mn, there was no significant difference between measurement results and certified values in four pretreatments. But, after DA and WA the results for Ca, K, Na, P and Zn differed significantly from the certified values.