Top PDF Calcium Hardness Analysis of Water Samples Using EDXRF Technique

Calcium Hardness Analysis of Water Samples Using EDXRF Technique

Calcium Hardness Analysis of Water Samples Using EDXRF Technique

An ecosystem comprises a community of living (biotic) organisms in association with the non living (abiotic) components of their environment, all interacting as a system. The health of an ecosystem is well described from the constitution of its non living components and water is one of the most important abiotic constituents of the human environment. The major desirable uses of water are water supply (domestic and industrial), recreation (swimming, boating), fishing (commercial and sport), irrigation, navigation, power production etc. Each use has its own requirements for the composition and purity of water and to ensure quality control, each body of water under use needs analysis on a regular basis. Therefore, it is vital to obtain accurate qualitative and quantitative information on the distribution of essential and potentially toxic elements in the water bodies.
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Chemical analysis of potable water samples from selected suburbs of Accra, Ghana

Chemical analysis of potable water samples from selected suburbs of Accra, Ghana

Potassium is an essential element in plant, animal and human nutrition (Lewis, 1997). In humans, potassium ions play a critical role in many vital cell functions, such as metabolism, growth, repair and volume regulation, as well as in the electric properties of the cell (Adriogue and Wesson, 1994). Potassium concentrations range between 2 mg/l and 15.9 mg/l. The Ca concentrations were between 14.4 mg/l and 43.2 mg/l. Calcium is a major constituent of various types of rock. It is one of the most common constituents present in natural waters ranging from zero to several hundred milligrams per liter depending on the source and treatment of the water. Calcium is a cause for hardness in water and incrustation in boilers. Magnesium is a common constituent in natural water. Magnesium salts are important contributors to the hardness of water which break down when heated, forming scale in boilers. Mg concentrations ranged between zero to 5.443 mg/l. Chemical softening, reverse osmosis, electro dialysis, or ion exchange reduces the magnesium and associated hardness to acceptable levels.
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J. Braz. Chem. Soc.  vol.19 número5

J. Braz. Chem. Soc. vol.19 número5

extraction of water samples with dichloromethane were applied prior to the pre-concentration of MX. The analyte was derivatised directly in the GC injector. The resulting MX trimethylsilyl derivative was identified and quantified using MS. Although this method offers a short analysis time, as well as satisfactory detection and quantification limits, the liquid-liquid extraction technique of isolating MX in water requires a large amount of sample and involves the use of fairly large amounts of organic solvents.
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Cerâmica  vol.59 número352

Cerâmica vol.59 número352

The μ-EDXRF analysis proved adequate to analyze the changes that occurred in osseointegration. The sample preparation is quite simple, since it does not require a specifi c procedure and or dehydration. Measurements can be performed under normal atmospheric conditions, without the need for high vacuum and are non-destructive (the same samples can be used for multiple analyzes). Our results are in agreement with previous studies. Lindgren et al. [23] and Ramírez-Fernández et al. [20] used the SEM-EDS technique to characterize and quantify the levels of Ca and P in osseointegration of synthetic implants and porcine xenografts in maxillary sinuses and found that the implants were gradually substituted by calcium-defi cient hydroxyapatite over the healing period and that newly formed bone had become closely attached to the xenografts (verifi ed by the gradual diffusion of calcium ions at the interface).
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Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

Development of a method for multielemental determination in water by EDXRF with radioisotopic source of 238Pu.

A highly sensitive and relatively inexpensive method for the analysis of Cr, Fe, Co, Ni, Cu, Zn, Hg and Pb in water samples using APDC and EDXRF with radioisotopic source of 238 Pu was implemented. The recovery values for all elements were close to 100% and the results for both accuracy and bias are less than 10%. The results using 238 Pu and 109 Cd source were very similar, but the 238Pu source is recommended owing to the lower measurement times. The DLs obtained are lower than the admissible levels of trace elements for drinking water according to national and international standards. The expanded uncertainty (in %), range to 15.4% for low concentration of the elements (2.5 – 5 µg/L) to 5.4% for the major concentration values (20 – 25 µg/L). Consequently, this analytical procedure can also be used alternatively for the determination of all these elements in water samples.
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Elementary Chemical Analysis in Leaves Infected by Fumagina by X-Ray Fluorescence Technique

Elementary Chemical Analysis in Leaves Infected by Fumagina by X-Ray Fluorescence Technique

from external level to internal level, it is followed by the emission of an X-ray with very defined energy or wave length, characteristic of the element.(Lachance, 1994). The analysis by X-rays fluorescence consists of three phases: excitation of the elements that constitute the sample, dispersion and detection of the X-ray emitted. (Nascimento,1993). The samples used in this work were infected and healthy leaves of Citric plants orange and lemon trees (Rutaceae-Citrus spp). Through the EDXRF technique Aragão et al., (2001) have observed that in the healthy olive leaves, from Mediterranean area, the concentration of iron was smaller than the one of calcium, while in the plant leaves infected by fumagina this relation was inverted, observing a quite high amount of iron in relation to calcium. This was the only work in which the variation in the concentration of Fe was measured in the plants infected by fumagina. Ivanova et al., (1999), using the EDXRF technique with radionuclide sources, measured elements concentrations in four species of the healthy plant leaves. Guohui and Shouzhong (1995) reported the direct determination of 25 elements (11 ≤ Z ≤ 82) in dry powdered plant materials by X-ray fluorescence spectrometry. It was using the pressed powder pellets of the plant samples, containing 1 g of the dry powdered material. The measured elements concentration was in the range from 0.2 to 30460 ppm, and the lower level detection (LLD) was in the range from 0.25 to 23.6 ppm. The aim of this work was to analyze the amount of the chemical elements in the healthy and fumagina infected leaves by EDXRF. Ajasa et al. (2004), using atomic absorption spectrophotometry, measured a total of 10 elements (11 ≤ Z ≤ 82) in powdered medicinal plant samples. The measured elements concentration was in the range from 0.21 to 36600 ppm.
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Direct determination of calcium in milk by atomic absorption spectrometry using flow-injection analysis

Direct determination of calcium in milk by atomic absorption spectrometry using flow-injection analysis

Eleven commercial milk samples purchased at local markets in Araraquara city (São Paulo, Brazil) and two standard reference materials (SRM 8435 Whole Milk Powder; SRM 1549 Non Fat Milk Powder) from National Institute of Standards and Technology (Gaithersburg, MD, USA) were analyzed for calcium determination. Four different sample preparation procedures were evaluated, such as dilution (1:250, v/v or 1:3000 m/v) in water or 1% (v/v) HNO 3 , decomposition in closed microwave oven digester system using 250 mg of sample plus 4 mL HNO 3 + 0.4 mL HCl concentrated acids or 4 mL of diluted (20% v/v) nitric acid. The heating program of the microwave oven used to decompose milk and determine calcium comprises the following time/power steps: 5 minutes/110-600 watts; 5 min/ 600– 600 watts; 10 min/ 1000–1000 watts; 15 min/ 0–0 watts.
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Matéria (Rio J.)  vol.22 número2

Matéria (Rio J.) vol.22 número2

Portland cement pastes are highly heterogeneous material and exhibits heterogeneous features over a wide range of length scales. Mechanical properties of microstructure can be determined using depth-sensing inden- tation. Coupled indentation/SEM technique can be used to location the indents and provides a way to deter- mine the mechanical properties of a specific phase. Thus, the present paper aims to determine the hardness of different phases of cement pastes prepared with different mineral admixtures including sugarcane bagasse ash. The microstructure of cement pastes prepared with different mineral admixtures is analyzed by X ray diffraction, scanning electron microscopy and dynamic hardness tests on polished sections. The different backscatter coefficient allows to differentiate anhydrous phases from C-S-H, calcium hydroxide, silica fume and quartz. A grid of indentation is used to determine the hardness of the different phases and a complete phase segmentation of the different samples is achieved. The results show that the hardness of the different phases follow the sequence (from higher to lower hardness) quartz, anhydrous particles, calcium hydroxide, C-S-H and agglomerated silica fume. The presence of agglomerated silica fume is clearly observed in scan- ning electron microscopy images and the poor mechanical properties of these areas might compromise the cement pastes. The microstructure of cement pastes prepared with sugarcane bagasse ashes is similar to the observed in samples with crushed quartz.
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Chemical analysis and Vickers hardness of orthodontic mini-implants

Chemical analysis and Vickers hardness of orthodontic mini-implants

In recent decades, there has been a growing demand for orthodontic treatment in dental offices by adult patients, which required the development of an efficient and aesthetically-pleasing anchorage system to enable and expedite treatment. The orthodontic mini-implant is a temporary skeletal anchorage device that allows the orthodontist to work safely because it eliminates the ensuing side effects on teeth used as anchorage in conventional treatment and does not depend on patient compliance 1 . The ease of installation and removal, possibility of insertion in

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Effect of thermal and mechanical cycles on the hardness and roughness of artificial teeth

Effect of thermal and mechanical cycles on the hardness and roughness of artificial teeth

of the material, resulting from manufacturing processes, and the mechanical action of brushing or chewing. The presence of these irregularities may have important clinical implications since they favor the adhesion and colonization of microorganisms [2]. Bac- terial adhesion and consequent formation of dental plaque on the surface of artiicial teeth result in staining and compromised aesthetic rehabilitation. Color stability is critical to the success of rehabilitation with dental prostheses and staining due to the in- crease in roughness and plaque accumulation is common. The rough surface caused by wearing the dentures and chemical deg- radation are also capable of affecting the brightness of artiicial teeth and cause extrinsic staining, resulting in harm to the esthetic appearance of dental prostheses. In addition, due to reduced roughness, teeth made of resin composite with a high degree of cross-linking may harbor lower numbers of microorganisms [14]. Although there have been technological advancements in the search for better materials, artiicial tooth wear is still common, causing loss of structure [12]. In this context, in vitro tests simu- lating the oral environment have been used to assess the clinical performance of artiicial teeth and other materials [11, 23, 17]. Thermal cycling is a commonly used thermal fatigue method for simulating intra-oral aging of dental materials, such as artiicial teeth [5]. In addition to the thermal effect, fractures or wear of ar- tiicial teeth may occur under continuous application of mechani- cal forces, resulting in loss of the dental prosthesis or ineffective repairs. Studies have found that different materials have shown a signiicant reduction in their mechanical properties after cyclic fatigue tests [9]. According to the authors’ knowledge, there is no study in the literature that has evaluated the inluence of thermal and mechanical cycles on the roughness and hardness of artiicial teeth. The effect of the number of cycles, which indicates the period of use of the dental prosthesis, also needs to be evaluated. Thus, the aim of the present study was to investigate the effect of thermal and mechanical cycles on the hardness and roughness of the different brands of artiicial teeth, since the oral environ- ment is one in which restorative materials are subject to numer- ous changes.Furthermore, the effect of different cycles on these properties was also evaluated in order to predict the longevity of use of dental prostheses.
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Water quality index using multivariate factorial analysis

Water quality index using multivariate factorial analysis

The evaluation of environmental effects generated by agricultural production on water quality became essential in Brazil after the creation of policies for the use and conservation of water resources. For such, water quality indices have been considered with the purpose of showing the spatial and temporal variation of water quality in a watershed. The objec- tive of this study was to develop a water quality index (WQI) applying the Multivariate Factorial Analysis (MFA) statisti- cal technique, which could indicate the influence of agricultural activities in the quality of water resources. Water in a predominantly farm watershed was monitored from Sept. 2003 to Sept. 2004. Monthly water collections were carried out at six sample points, and eight parameters were analyzed: nitrate, ammoniacal nitrogen, ammonia, total phosphorus, electrical conductivity, pH, suspended solids and turbidity, which were considered important due to the agricultural man- agement adopted in the region. Results indicated a contamination of agricultural origin along the basin. Factorial analy- sis showed that ammonia, ammoniacal nitrogen and nitrate parameters were the ones that most contributed in deter- mining the WQI.
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Evaluation of phenotypic and genotypic alterations induced by long periods of subculturing of Cryptococcus neoformans strains

Evaluation of phenotypic and genotypic alterations induced by long periods of subculturing of Cryptococcus neoformans strains

C. neoformans strains exists as five serotypes (A, B, C, D, AD), based on differences in the capsule that consists of 88% of glucuronoxylomannan structure (Cherniak 1988). In this study we observed that 50% of the strains are C. neoformans var. neoformans, serotype A and 50% are C. neoformans var. gattii, serotype B. C. neoformans var. gattii is predominately restricted to tropical regions; however, a recent outbreak of C. neoformans var. gattii infections on Vancouver Island in Canada (Hoang et al. 2004) has raised the level of interest in this pathogen. Except for the recently described high prevalence of serotype C infections in AIDS patients living in sub-Saharan Africa (Litvintseva et al. 2005), the majority of cryptococcosis due to serotype B and C strains occurs in immunologically normal individuals. Disease with serotype A and D strains occurs more often in immunosuppressed hosts (Chen et al. 2000) but has also been described for immuno- competent patients (Jain et al. 2005).
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J. Braz. Chem. Soc.  vol.24 número9

J. Braz. Chem. Soc. vol.24 número9

performed to evaluate the solid-phase extraction parameters. Five variables were studied at two levels (low and high levels), and three central points were included to estimate the experimental variance and to check for loss of linearity between the levels chosen for each variable. FFD resulted in a total of 19 randomized trials, which were performed in a single day. The variables and their high and low levels were chosen according to preliminary experiments. After the experiments, the recoveries were calculated for each analyte in each run. The factorial design was evaluated from the normalized recovery responses (R n ) obtained in each of
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Preparation, Microhardness Characterization on Untreated And Treated  With Electric Stressed Samples on The Inorganic Tunable Laser Dye  Rhodamine Doped PMMA

Preparation, Microhardness Characterization on Untreated And Treated With Electric Stressed Samples on The Inorganic Tunable Laser Dye Rhodamine Doped PMMA

Polymers are used extensively in many applications in thin film form; for example as free standing films, or as coatings which are next to rigid substrates. In electronic packaging, adherent epoxy under fills can be used to modify the localized stress concentrations 1 , which can arise due to differences in coefficients of thermal expansion of the different materials. The mechanical state within the polymer necessarily varies from point to point within the thin film, as can the strength of the adhesion between the polymer and the substrate. In the past decade many advances have been made in the field of optical materials, that is tunable solid state lasers, non-linear sensors, luminescent solar concentrators and optical sensors. One of the most important inorganic dye useful as tunable laser material Rhodamine (Rh 6G) was introduced in the year 1967. PMMA is considered as one of the most efficient dye matrices with excellent optical, thermal, photochemical and dimensional stability 2 . As such it has been widely used for laser and non-linear optical materials. In the present work, effect of Load, Load dependent nature of Microhardness measurement and Doping Effect on untreated samples and Microhardness studies on the effect of charge due to
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An analysis of water samples surrounding swine farms in Timis County – A practical guide

An analysis of water samples surrounding swine farms in Timis County – A practical guide

Importance: Chlorine ions constitute a majority of inorganic anions in water and wastewater. Although there is no known toxicity of high concentrations of chlorides in humans, adjusting the concentration depends on the taste. It is essential to monitor the concentration of chloride in boiling systems to prevent degradation of metal parts. Too elevated levels of chloride has corrosive effect on stainless steel and can be toxic to plants.

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Mat. Res.  vol.13 número1

Mat. Res. vol.13 número1

in pH in ape teeth after the root canals were dressed with calcium hydroxide. These authors found that the presence of calcium ions is necessary for the activity of the complement system in the immune reaction, and that the abundance of calcium ions activates calcium- dependent ATPase (adenosine triphosphatase), which is associated with the formation of hard tissue. They also stated that calcium hydroxide activates alkaline phosphatase due to its high pH and that the optimal pH for the activity of alkaline phosphatase, which varies according to the type and concentration of substrate, the temperature, and the enzyme source, is around 8.6 to 10.3.
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The analysis of solidification process of ferritic-austenitic cast steel

The analysis of solidification process of ferritic-austenitic cast steel

One of the most common defects leading to the rejection of faulty castings made of duplex cast steel is hot cracking. Hot cracking – differently from cold cracking which occur on cooling, when the material exhibits already distinct elastic properties – proceeds in the semi-solid state, particularly when the temperature of solidifying casting is close to the equilibrium solidus point. There exist a range of temperatures in the vicinity of the solidus point within which the solidifying metal shows very small deformation ability and small strength. Therefore even little stresses occurring at the solidification stage and caused by density difference between ferrite and austenite, or restricted shrinkage, or various temperature gradients, can be the reason of hot cracking. Copper addition, as it is used in cast steel grades implemented in Polish power industry applications, decreases the temperature of the end of solidification, thus affecting beneficially the surface reproduction quality, but on the other hand it can promote, along with several other elements contained in duplex cast steel, the peritectic transformation during the last stage of solidification. The presence of peritectic solidification, i.e. strictly speaking the structural stresses accompanying that process, is the well-known and significant reason of the increased steel defectiveness in the continuous steel casting (CSC) technology if the steel with carbon content promoting the peritectic transformation is processed.
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An Improvement of Calcium Determination Technique in the Shell of Molluscs

An Improvement of Calcium Determination Technique in the Shell of Molluscs

The ion calcium is one of the most important elements present in the shell of molluscs, mainly the gastropods, to which the shell is straightly related to protection of the animal against predators and to avoid the dehydration. But the shell is not an inert mineral structure. Calcium is a metal that exerts an essential role on the biology of the snails, once that, this ion is the main component of the snails shell, constituting an important limiting factor that determine the distribution and survival of the adult snails, oviposition rate, survival and development of eggs
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Braz. J. Pharm. Sci.  vol.50 número3

Braz. J. Pharm. Sci. vol.50 número3

In order to obtain maximum extraction eficiency, some important parameters such as extraction solvent type must be investigated in detail. In conventional DLLME, the extraction solvent should have a higher density than water to be collected at the bottom of the test tube after centrifuging. Also, the extraction solvent must have excellent extraction ability for target analyte and low solubility in the aqueous sample. In this study, a series of sample solutions were studied by using 0.6 mL acetonitrile containing 20 µL different extraction solvents such as carbon tetrachloride, chlorobenzene and dichloromethane. Laboratory observations showed that a two-phase system was not observed when dichloromethane was used as the extractant due to its high solubility in aqueous solution (Daneshfar, Khezeli, Lotfi, 2009). According to the experimental results (Figure 1), carbon tetrachloride had the best extraction eficiency for CPM. Therefore, carbon tetrachloride was selected as the extraction solvent in the subsequent experiments.
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Comparison between two methods of ionized calcium measurement in newborns

Comparison between two methods of ionized calcium measurement in newborns

In almost all Brazilian laboratories, only total calcium is routinely measured, and iCa concentration is indirectly calculated based on total calcium, total protein and albumin concentrations. Errors associated with the measurement of those and other variables, such as pH, contribute to the dificulty of producing useful formulae to calculate iCa indirectly. Direct measurement of iCa by potentiometry is the method of choice for iCa determination, but it is an expensive analysis (8) . Therefore, the aim of this study
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