Graphite Furnace Atomic Absorption Spectrophotometry

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Concepts, Instrumentation and Techniques in Atomic Absorption Spectrophotometry

Concepts, Instrumentation and Techniques in Atomic Absorption Spectrophotometry

The longitudinally-heated furnace has a major liability. The electrical contacts at each end of the tube must be cooled. As a result, there must always be a tempera- ture gradient along the length of the tube, the tube ends adjacent to the electrical contacts being cooler than the central portion. This temperature gradient can cause vaporized atoms and molecules to condense as they diffuse to the cooler tube ends. This may produce interferences, the most common type being the incomplete re- moval of analyte or matrix from the tube. Incomplete removal of matrix during pyrolysis can increase the magnitude of background absorption during atomiza- tion. Incomplete removal of analyte during atomization is more serious. It creates "carryover" or "memory", wherein a portion of the analyte in the current sample remains in the tube and contributes to the analytical signal for the following sam- ple. This produces erroneously high analytical results and poor precision. To minimize carryover, most longitudinally-heated furnace heating programs use one or more cleanout steps after the atomization step. A cleanout step involves the application for several seconds of full internal gas flow and a temperature equal to or greater than that used for atomization to remove residual sample components. While this technique works well for the more easily atomized analytes, it is not always successful with those analytes that require higher atomization tempera- tures. The use of a high temperature cleanout step may also reduce tube lifetime. The transversely-heated graphite furnace eliminates many of the problems asso- ciated with the longitudinally-heated furnace. The graphite tube of the trans- versely-heated furnace, shown in Figure 5-2, includes integral tabs which protrude from each side. These tabs are inserted into the electrical contacts. When power is applied, the tube is heated across its circumference (transversely). By applying power in this manner, the tube is heated evenly over its entire length, eliminating or significantly reducing the sample condensation problems seen with longitudi- nally-heated furnace systems.
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Determination and Evaluation of Mineral Constituents of Medicinal Plants used for the Treatment of Asthma and other Ailments by Atomic Absorption Spectrophotometry

Determination and Evaluation of Mineral Constituents of Medicinal Plants used for the Treatment of Asthma and other Ailments by Atomic Absorption Spectrophotometry

The comparative study of iron was carried out by taking the biological samples such as serum, urine, serum thyroid hormones, thyroid stimulating hormone, free triiodothyroxine, and free thyroxin of goitrous female patients to find out the deficiency of iron in women [13, 14]. Microchip was used for the purification of proteins and magnetic resonance imaging while as metal ions was examined by means of chemical and biological separations [15]. Selenium level from different medicinal plants was found by using the method of Microwave-assisted extraction at different concentrations of nitric acid and hydrochloric acid solutions. The concentration of selenium present in medicinal plants was also examined on highly sensitive equipment electrothermal atomic absorption spectrometry [16]. The concentration of heavy metals in scalp hair of hypertensive patients were observed through wet digestion method by using flame and graphite furnace atomic absorption spectrometry [17].
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Optimization of Chromium, Nickel and Vanadium analysis in crude oil using graphite furnace atomic absorption spectroscopy

Optimization of Chromium, Nickel and Vanadium analysis in crude oil using graphite furnace atomic absorption spectroscopy

For quantitative measurement of metals in crude oil, numerous analytical methods are used for the determination of the metallic elements present in organic liquids. Among those, atomic absorption spectrophotometry (AAS) is one of the most used techniques for the determination of metal cations due to the crude oil sample contain bulk of volatile organic compound and the analyte metal which can absorp light [5]. Flame excitation is an apparently attractive technique due to the simplicity in the preparation of the sample and speed of measurement. However, it has several limitations, in particular, its relatively low sensitivity and the mechanical difficulties presented by aspiration of highly viscous samples which causes poor reproducibility. Because of this, and because metal elements such as vanadium, which form refractory oxides make it difficult or impossible to volatilize them, the use of the graphite furnace has been introduced as the source of volatilization and excitation [6].
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Degradation Process of Graphite Furnace Estimated from the Atomic Gas Temperature of Iron in Graphite Furnace Atomic Absorption Spectrometry

Degradation Process of Graphite Furnace Estimated from the Atomic Gas Temperature of Iron in Graphite Furnace Atomic Absorption Spectrometry

an absorption, is measured for a spectral line related to each energy level. Then, a term expressed as F ¼ 2 gA, where , g and A respectively mean the wavelength, the statical weight and the Einstein coefficient for the spontaneous emission of a spectral line, is calculated using literature data for each analytical line. Therefore, the atomic gas temperature in the graphite furnace can be estimated from the absorbance ratio between two spectral lines whose lower energy levels are different. Moreover, the variations in the atomic gas tem- perature can be determined not only by the temperature distribution, but by the spatial distribution of iron atoms through their diffusion in the atomization stage. On the other word, it reflects that the atomic gas generates at a center (high-temperature area) and moves to an edge (low-temper- ature area) of the furnace.
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Absorption and Emission of Radiation by an Atomic Oscillator

Absorption and Emission of Radiation by an Atomic Oscillator

The theory of absorption and emission of electromagnetic radiation by an oscilla- tor consisting of the atomic nucleus and one electrically charged particle is de- duced using classical electrodynamics. In the steady state of an atom, emission and absorption of electromagnetic radiation are equal, so the atom is stable. In order to include reactive effects of electromagnetic radiation in the motion equa- tions, the Newton equation is modified by adding the radiative reaction force. This paper is an introduction to the derivation of the basic assumptions of quan- tum mechanics.
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Routine Maintenance for Atomic Absorption Spectrophotometers

Routine Maintenance for Atomic Absorption Spectrophotometers

At times, graphite particulates may accumulate on the capil- lary tip and should be carefully removed with a tissue. If these particulates are not removed, the dispensing characteristics of the capillary may change. Contamination of the capillary may become a problem when using some matrix modifiers. In such cases, direct the capillary to a vial containing 20% HNO 3 , draw up 70 µL, and stop the autosampler while the capillary is in the vial. After a period of a few minutes, the autosampler RESET should be utilized to rinse out the acid solution. This will clean the internal and external areas of the capillary. Similarly, organic residues can be removed by directing the capillary to a vial of acetone and repeating the above proce- dure. The PTFE capillary should be treated carefully during cleaning and operation. If bends or kinks appear, it can take time to reshape, and while doing so the repeatability of injec- tion may be degraded. If the capillary tip is damaged, the dam- aged portion should be cut off at a 90° angle with a sharp scalpel or razor blade.
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Atomic absorption spectrometry in wine analysis

Atomic absorption spectrometry in wine analysis

Validation of developed analytical proce- dures including quality control of analytical results obtained is important characteristic presented or discussed in most of the papers dealing with wine analysis. It is well known that analysis of certified reference materials is the best way to confirm ac- curacy and reliability of analytical methods; how- ever, reference wines with certified concentrations of minor, trace or ultratrace elements are not avail- able [132]. That is way in common case added/found method has been used to establish the accuracy and precision of the analytical method developed. Another alternative widely used when direct method of analysis is tested is parallel de- termination of trace analytes by using previous wine sample digestion [28, 30, 36, 49, 57, 58, 71, 86, 109]. The compatibility of two methods (AAS and TXRF) was validated by parallel analysis of five samples for Fe and Cu and an agreement within the statistical uncertainty involved in both techniques was found [38]. Arsenic content deter- mined by HG AAS or HG AFS is typically con- firmed by ETAAS after wine sample digestion [28, 108]. In the frame of Comparison 16 of the Inter- national Measurement Evaluation Programme (IMEP) focused on the evaluation of measurement performance for the determination of the Pb mass fraction in a commercial red wine most widely used instrumental method was ETAAS, around 5% of results were obtained with ICP-MS and about 8% with ICP-AES) [133]. It was concluded that the results obtained using electrothermal atomic absorption spectrometry (ETAAS, recommended in EC Regulation 2676/90) were not significantly different from those obtained using other tech- niques.
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Quantification of gallium, indium and thallium in meteorites and other geological materials by graphite furnace atomic absorption spectrometry : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey

Quantification of gallium, indium and thallium in meteorites and other geological materials by graphite furnace atomic absorption spectrometry : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University

Hydride - Generat ion Atomic Abs orpt ion Spectrometry for the Quant i f ication of Germa nium in Iron Meteor ites An al.. Separation of I ron from I nd ium with Cupf erron Proc..[r]

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In-Situ Digestion of Serum Samples in Graphite Furnace Prior to Determination by ETAAS

In-Situ Digestion of Serum Samples in Graphite Furnace Prior to Determination by ETAAS

was much more eective if the mixture modier and digested sample were rst pre-pyrolyzed on the furnace prior to the atomization. Determination of Pb, Mn and Zn in serum at a concentration of 0.1 ppb-1.0 ppm was performed by this method. Percent relative standard deviations for seven replicates in measurements were found to be 3.4, 3.1 and 4.0, respectively. The accuracy of technique was established by analyzing standard reference materials. The results for determination of the tested elements were within the range of certied values.

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Separation/Enrichment of Copper and Silver Using  Titanium Dioxide Nanoparticles Coated with Poly Thiophene and Their Analysis by Flame Atomic  Absorption Spectrophotometry

Separation/Enrichment of Copper and Silver Using Titanium Dioxide Nanoparticles Coated with Poly Thiophene and Their Analysis by Flame Atomic Absorption Spectrophotometry

affecting the adsorption and desorption steps for the mentioned ions were investigated and optimized. The studied factors include effects of pH, adsorption and de- sorption time, type, concentration, and volume of the eluent for elution of silver and copper ions, break through volume and effect of coexisting ions on separation and determination of these heavy metals. Poly-thiophene mo- dified titanium dioxide was successfully applied for solid phase extraction of silver and copper in water samples and flame atomic absorption spectrometry (FAAS) was used to measure the above ions in solutions. Finally, the mentioned adsorbent was validated using thermogravim- etry analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD).
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The Effect of Ammonium Pyrrolidinedithiocarbamate (APDC) Complexing Agent on the Determination Of Copper Trace in Steel Using Atomic Absorption Spectrophotometry

The Effect of Ammonium Pyrrolidinedithiocarbamate (APDC) Complexing Agent on the Determination Of Copper Trace in Steel Using Atomic Absorption Spectrophotometry

A method of solvent extraction is described for concentrating and separating the copper from an aqueous alkaline solution (pH 9-10) of steel into an organic solvent prior to analysis by flame atomic absorption spectroscopy. In this research first, ammonium pyrrolidinedithiocarbamate (APDC) as a chelating agent, and tartaric acid as masking agent for ferric ion, were used then, solvent extraction, separation of copper from steel and subsequent determination of copper in the organic solvent were carried out. The copper content of four separate samples of each of the standard steels was extracted as a Cu/APDC complex into MIBK. The results obtained for steel samples were very near to the certificated values particularly when iron is added to the standard solutions. Thus, APDC could be used successfully in the extraction of copper from steel samples even when iron is not added to the standards.
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Assessment of Heavy Metals in Rice using Atomic Absorption Spectrophotometry – A Study of Different Rice Varieties in Pakistan

Assessment of Heavy Metals in Rice using Atomic Absorption Spectrophotometry – A Study of Different Rice Varieties in Pakistan

Accumulation of heavy metals in human body is known to possess quite toxic effects. They are ubiquitously found in earth crust and tend to accumulate in crops grown in heavily contaminated soil and hence enter the food chain. This study was based on the analysis of heavy metals in eighteen selected varieties of rice (Oryza sativa L.) that circulates in local market of Karachi, Pakistan. Few heavy metals namely, Cadmium (Cd), Chromium (Cr), Cobalt (Co), Copper (Cu), Lead (Pb), Manganese (Mn), Nickel (Ni), and Zinc (Zn) were analyzed using Atomic Absorption Spectroscopy (AAS). Rice samples were digested using nitric acid (conc.). Average concentrations of Cd, Co, Cr, Pb, Ni were 7.3, 10.6, 107, 117, 139 µg kg -1 of rice respectively, whereas, the respective concentrations of Cu, Mn, and Zn were found to be 4.7, 9.7, and 14.6 mg kg -1 of rice. The results from this study when compared with previous studies revealed that the Pakistani rice is found to have relatively less concentration of these heavy metals.
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Air-assisted Liquid Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry for Preconcentration and Determination of Trace Amount of Co(II) and Ni(II) Ions in Water Samples

Air-assisted Liquid Liquid Microextraction Combined with Graphite Furnace Atomic Absorption Spectrometry for Preconcentration and Determination of Trace Amount of Co(II) and Ni(II) Ions in Water Samples

A simple, rapid and efficient method has been developed for the extraction, preconcentration and determination of cobalt(II) and nickel(II) ions in water samples by air-assisted liquid-liquid microextraction (AALLME) coupled with graphite furnace atomic absorption spectrometry (GFAAS). In the proposed method, much less volume of an organic solvent was used as the extraction solvent in the absence of disperser solvent. Fine organic droplets were formed by sucking and injecting of the mixture of aqueous sample solution and extraction solvent with a syringe for several times in a conical test tube. After extraction, phase separation was performed by centrifugation and the enriched analytes in the sedimented phase were determined by GFAAS. Several variables that could affect the extraction efficiency were investigated and optimized. Calibration graphs were linear in the range of 6.5-100 ng l -1 . Detection limits for Co and Ni were 2.3 ng l -1 and 3 ng l -1 , respectively. The accuracy of the developed procedure was checked by analyzing NRCC-SLRS4 Riverine water as a certified
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The Effect of two Comlexing Agents (Naddc and Zndbc) on the Determination of Copper Trace in Steel Using Atomic Absorption Spectrophotometry

The Effect of two Comlexing Agents (Naddc and Zndbc) on the Determination of Copper Trace in Steel Using Atomic Absorption Spectrophotometry

solubility of the complex in the solvent must be high if a good separation is to be obtained. A suitable organic solvent for atomic absor ption determinations should be combustible, exhibit a reasonable aspiration rate and the combustion product should not absorb radiation from the hollow cathode lamp. The number of solvents that can be successfully aspirated into a flame is limited. Chloroform and carbon tetrachloride which were widely used in colorimetric work, then aspirated caused the flame to be extinguished. Of the flammable solvents, acetylacetone (AcAc), isobutylacetate, n-butyl ether and methyl isobutyl ketone (MIBK) were tested. They all showed a tendency to lift the flame from the burner and to make the flame luminous. It was possible by restricting the acetylene flow as much as safety possible before aspirating the solvent to hold the flame on the burner, but except for MIBK, the flame remained luminous. MIBK is only sparingly soluble in the aqueous phase and has low viscosity, giving high nebulization rate and efficiency. With this solvent the flame was steady and no absorption due to the solvent was observed. Organic solvents cause an increase in the absorption signal of the sample in the flame due to greater efficiency in producing free atoms and to more effective nebulization. Therefore, it is often necessary to
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ANALYSIS OF UNCERTAINTY MEASUREMENT IN ATOMIC ABSORPTION SPECTROPHOTOMETER

ANALYSIS OF UNCERTAINTY MEASUREMENT IN ATOMIC ABSORPTION SPECTROPHOTOMETER

Quality of result (accuracy) depends on the uncertainty of measurement value of the test. If uncertainty of measurement is more there may be doubt of about the final result. The final result of Atomic Absorption Spectrophotometer gets affected by the number of parameters; we should take in to account will calculating the final result.

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On Graphite Transformations at High Temperature and Pressure Induced by Absorption of the LHC Beam

On Graphite Transformations at High Temperature and Pressure Induced by Absorption of the LHC Beam

) in the experiments is quite similar to the lateral section of the hottest region in the energetic particle cascade. The most important difference is that contrary to the laser beam, effective only on a very thin front surface layer of the specimen (in most cases in contact with vacuum), the high energy hadronic and electro-magnetic cascade need a depth range of rather meters than micrometers to develop, so they deposit energy internally in a large part of the graphite volume, the upstream face being remarkably less heated than the maximum, at about 2 m. This again acts in favour of melting rather than vaporisation, since most of the material submitted to intense heat generation has no access to a free surface of sublimation (other than several vacuum pumping channels in the core). Moreover, a high stress (in solid) or pressure (in liquid) is more likely to concentrate in and will be more difficult to release from the central parts of the core.
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Determination of the absorption coefficient of chromophoric dissolved organic matter from underway spectrophotometry

Determination of the absorption coefficient of chromophoric dissolved organic matter from underway spectrophotometry

Unfortunately, every time we determined the absorption spectrum of the NaCl solution, variations were observed during the 20 replicate measurements that were collected for each NaCl-solution sample, which may be due to impurities in the salt. Specifically, after injecting the NaCl solution, an absorbance peak rapidly developed between 350 and 450 nm during the typical 20 seconds needed to collect the 20 spectra. Simultaneously, the absorbance of the NaCl solution gradually decreased below 300 nm, potentially suggesting that a photochemical reaction was taking place as the NaCl solution was exposed to the UV-visible light. This effect was never observed when we measured natural seawater samples, ultrapure or HPLC-grade water. Thus, to perform salinity corrections, we could not use the average of the 20 spectra as was done for the samples, ultrapure and HPLC-grade water. Instead, we were forced to use the very first spectrum collected immediately after the injection of the NaCl solution. This first spectrum was minimally affected by the peak between 350 and 450 nm.
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Aspects of atomic absorption analysis including the assay for selenium

Aspects of atomic absorption analysis including the assay for selenium

A sodium chloride solution was sprayed into the flame to produce a visual indication of the efficiency of the plasma in converting the components of the spray into a suitable form for absorption, or emission,measure­ ments. It was very difficult to excite the characteristic sodium emission. Obviously the spbay was not being evap­ orated. Several experimental alterations to the plasma exhaust were tried, and eventually a small measure of success was achieved by allowing the spray to mix with the hot gases of the plasma in a long silica tube. The exhaust gases at the end of the tube, however, were too cold (about 500°C), to be effective for atomic absorption.
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Qualification of Atomic Absorption Spectrometer in Prospective View of Pharmaceutical Analysis

Qualification of Atomic Absorption Spectrometer in Prospective View of Pharmaceutical Analysis

AIQ is important in generating the quality data for analytical method validation and provides the contribution towards the quality analysis. AIQ involves the four discrete steps of qualification such as design qualification (DQ), installation qualification (IQ), operational qualification (OQ) and performance qualification (PQ). Atomic absorption spectrometer (AAS) is among the group C instruments where conformance is complex; highly me- thod specific and the conformity bounds are determined by their application and full qualification process ap- plies [1]. DQ is a documented activity for necessary functions and performance specifications (technical and en- vironmental safety) of an analytical instrument for its intended applications as well to meet user requirement which is followed by conscious decision of technical management. IQ ensured analytical instrument perfor- mance testing that is installed in suitable environment like temperature, humidity, dust and vibration levels with sufficient space for placing auxiliary gadgets as per recommendation of manufacturer. OQ is a performance ve- rification of analytical instrument according to its overall intended anticipated operating ranges. PQ is a docu- mented verification that analytical instrument consistently performed and gave reproducible results for a prolong period [2]. Qualification and validation always run side by side because former is an act of planning to carry out and recording tests on equipment while the latter is an act of documentation of acquired results while to check the performance of equipment in series of tests is system suitability checking [3]-[5]. Analytical instrument must be qualified first for verification of system suitability and validation of analytical method. AIQ is not a onetime event; it starts from definition until retirement of instrument. If the analytical instrument is not qualified, it will not work well for its intended application [6]. The qualified instrument performs as per set criteria throughout the whole operational life [7]. The qualification of atomic absorption spectrometer (AAS) is prime important for electrolyte determination in various formulation of haemodialysis solutions and water for diluting the concen- trated haemodialysis solutions. AAS also is used for heavy and trace metals estimation in active pharmaceutical ingredients (API) for production of best quality end-user products as a part of limit tests in pharmacopoeial mo- nographs [8]-[10]. The objective of this paper is to qualify AAS from PG-Instruments, UK as a part of good analytical laboratory practice. This document links the user requirements, functional specifications, design spe- cification (DQ) and testing specification (IQ, OQ, PQ) per the V-model presented in Figure 1.
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Optimize Determination of Calcium Using Flame Atomic Absorption

Optimize Determination of Calcium Using Flame Atomic Absorption

Ionization interferences: an appreciable fraction of alkali, alkaline earth element may be ionized in the flame. Since we are measuring the unionized atoms, either emission or absorption signals will be decreased. However the presence of other easily ionized elements in the sample will add free electrons to the flame and suppress ionization of the test element.

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