Furnace Atomic Absorption Research Articles

Prediagnostic toenail cadmium and zinc and subsequent prostate cancer risk.

Cadmium is a recognized human lung carcinogen that has also been positively associated with prostate cancer mainly in occupationally exposed men. The association between dietary and supplemental zinc intake and prostate cancer has not been consistent in epidemiologic studies. We evaluated the association between prediagnostic toenail cadmium and zinc concentrations and risk of prostate cancer in a cohort in which the primary route of exposure to cadmium and zinc is the diet. Included in the analysis were 115 prostate cancer cases and 227 age-matched controls nested in the prospective CLUE II study located in Washington County, MD. Participants provided toenail samples at baseline in 1989. Furnace atomic absorption and flame atomic absorption were used to determine toenail cadmium and zinc concentrations, respectively. Odds ratios (OR) and 95% confidence intervals (CI) were estimated from conditional logistic regression models. Median toenail cadmium and zinc concentrations did not statistically significantly differ between prostate cancer cases (cadmium, 45.9 ppb; zinc, 155.3 ppm) and controls (cadmium, 54.5 ppb; zinc, 164.0 ppm). Prostate cancer risk did not increase with increasing concentrations of cadmium (P trend = 0.9) and did not decrease with increasing concentrations of zinc (P trend = 0.2). For both metals, the ORs for the top four fifths were each below 1.0 when compared with the bottom fifth. Men who have high toenail cadmium concentrations in the range observed in this general population sample were not at an increased risk for prostate cancer. Although there was no evidence of a linear dose-response, these findings suggest that risk of prostate cancer may be slightly lower among men with moderate and higher zinc intake.

Determination of Urinary Beryllium, Arsenic, and Selenium in Steel Production Workers

Some of the most pernicious dangers of pollution arise from the presence of traces of toxic elements in the environment. In this work, we report on the determination of beryllium, arsenic, and selenium in the urine of steel production and steel quality control (QC) workers, in comparison to healthy control subjects. The urine samples were digested by a microwave system. Graphite furnace and hydride atomic absorption was used for the quantitative measurements of Be and As and Se, respectively. A quality control method for these procedures was established with concurrent analysis of Standard Trace Metals 7879 Level II and NIST SRM 2670 (Toxic Elements in Freeze Dried Urine). The results show that the urinary levels of these elements in steel production (As, 38.1 +/- 28.7 microg/L; Be, 1.58 +/- 0.46 microg/L, and Se, 69.2 +/- 28.8 +/- g/L) and in quality control workers (As, 23.9 +/- 18.1 microg/L; Be, 1.58 +/- 0.46 microg/L, and Se, 54.8 +/- 25.1 microg/L) are significantly higher than in the controls (As, 10.3 +/- 8.7 microg/L; Be, 0.83 +/- 0.46 microg/L; and Se, 32.3 +/- 13.5 microg/L). The possible connection of these elements with the etiology of disease and the possible role of selenium as a protective agent against the oncogenic and teratogenic action of other substances is discussed. We suggest the need for improvement of environmental conditions in the workplace through better ventilation and industrial hygiene practices.

Speciation of cadmium, copper, lead, and zinc in contaminated soils

To investigate the activity of free cadmium (Cd2+), copper (Cu2+), lead (Pb2+), and zinc (Zn2+) ions and analyze their dependence on pH and other soil properties, ten contaminated soils were sampled and analyzed for total contents of Cd, Cu, Pb, and Zn (CdT, CuT, PbT, and ZnT, respectively), 0.43 MHNO3‐extractable Cd, Cu, Pb, and Zn (CdN, CuN, PbN, and ZnN, respectively), pH, dissolved organic matter (DOC), cation exchange capacity (CEC), ammonium oxalate extractable aluminum (Al) and iron (Fe), and dissolved calcium [Ca2+]. The activity of free Pb2+, Cd2+, Cu2+, and Zn2+ ions in soil solutions was determined using Donnan equilibrium/graphite furnace atomic absorption (DE/GFAA). The solubility of Cd in soils varied from 0.16 to 0.94 μg L‐1, Cu from 3.43 to 7.42 μg L‐1, Pb from 1.23 to 5.8 μg L‐1, and Zn from 24.5 to 34.3 μg L‐. In saturation soil extracts, the activity of free Cd2+ ions constituted 42 to 82% of the dissolved fraction, for Cu2+the range was 0.1 to 7.8%, for Pb2+ 0.1 to 5.1% and for Zn2+2 to 72%. The principal species of Cd, Cu, Pb, and Zn in the soil solution is free metal ions and hydrolyzed ions. Soil pH displayed a pronounced effect on the activity of free Cd2+, Cu2t, Pb2+, and Zn2+ ions.

Chemical analyses of mechanochemical reaction products of α-Si3N4 in ethanol and other lower alcohols

Recently, ceramic engines made of silicon nitride have attracted widespread interest because the exhaust does not pollute the environment [1]. To develop the ceramic engine, it is necessary to understand the tribological characteristics of silicon nitride in an alcohol fuel such as ethanol. In our previous report [2], silicon nitride showed lower friction in lower alcohols such as methanol and ethanol, even at low sliding speed. To explain the results, we considered the formation of a lubricating film due to the tribochemical reaction of the silicon nitride with alcohols, as shown in Fig. 1. That is, the surface of the silicon nitride is oxidized and esterified to form soluble silicon alkoxides which are effective in reducing the friction. We need to clarify the nature of the tribochemical films. Generally, the yields of tribochemical reaction products are too small to allow their nature and properties to be characterized. To overcome this difficulty, Gates and Hsu [3] used micro-sample wear tests, in which silicon nitride was slid in trace amounts of higher alcohols, octanol and decanol, and they detected secondary ion mass spectroscopy (SIMS) peaks of Si(OR)4 (R: C8H17 and C10H21) and gel permeation chromatography/graphite furnace atomic absorption (GPC/GFAA) peaks of silicon containing polymers. It is quite difficult, however, to detect trace amounts of the reaction product of Si3N4 in lower alcohols because lower alcohols are volatile. Systematic studies of the tribochemical products of silicon nitride in lower alcohols have not yet been made. Milling tests were therefore conducted to accelerate the mechanochemical reaction of silicon nitride with ethanol and other lower alcohols. Milling tests were performed using a planetarytype micro-pulverizer (Fritsch Ltd, p-7). AE-Silicon nitride powder (10 mmol, 1.4 g, diameter 1.5 im, purity 99.9‡%) was milled for 60 h with 25 ml ethanol (H2O , 0.005%) in a pot made of silicon nitride. After the milling test, the mechanochemical reaction mixture was filtered under reduced pressure through a PTFE filter with pore size of 0.2 im to remove any unreacted silicon nitride powder. The filtrate was concentrated, then chloroform was added to the concentrate. A precipitate of a pale yellow solid separated out. The pale yellow solid was filtered off, washed with chloroform, and dried. After the evaporation of solvent from the filtrate, a yellow residue remained. These separated substances were characterized by Fourier transform infrared (FTIR) absorption spectroscopy, proton nuclear magnetic resonance spectroscopy (1H-NMR), gel permeation chromatography (GPC) and mass spectroscopy (MS). Pale yellow solids precipitated from the reaction mixture (milling time: 60 h) were analysed by means of FTIR, of which the spectrum is shown in Fig. 2. The peaks of the pale yellow solid are generally identical with those of an authentic sample of silica gel [4, 5] except for the absorption bands of 3000– 2800 cmy1, which are attributed to methyl (CH3) or methylene (CH2) stretching vibration. These absorption bands are observed when silica gel is esterified by alcohol [6, 7]. Precipitation of silica gel from the liquid phase suggested that a silicon component dissolved in ethanol during milling. Two possible mechanisms of silica gel formation were proposed, as shown in Fig. 3. In route 1, silicon nitride undergoes oxidation by oxygen to form silicon oxide. The silicon oxide reacts with ethanol and the adsorbed hydroxyl group to produce silicon alkoxide (Si(OR)n(OH)4yn), which is soluble in ethanol. Silicon alkoxide is hydrolysed and condensed to form long-chain polyoxysilane and twoor three-dimensional cross-linked polyoxysilane. Further condensation of polyoxysilane resulted in the precipitation of silica gel. In route 2, the

Separation and preconcentration of trace vanadium in aqueous solution using trioctylmethylammonium chloride-loaded silica gel.

The separation and preconcentration of trace vanadium from an aqueous solution for a graphite furnace atomic-absorption spectrometric (GF-AAS) determination was studied using silica gel loaded with trioctylmethylammonium cloride (Capriquat). A sample solution containing V was adjusted to pH 6.0. The solution was then passed through 1.0g of Capriquat loaded in a silica gel column at a flow rate of 10 ml min-1. The V collected on the Capriquat-loaded silica gel on the column was eluted with 10 ml of 0.5 M perchloric acid, and then determined by GF-AAS. In this method, over 99% of the V was adsorbed at about pH 6.0. The calibration curve was linear from 0.05 to 2.5 μg/l of V. The proposed method has been applied to the determination of V in river water and seawater samples.

Analysis of micro amounts with furnaces: the contribution of Klaus Dittrich to trace analysis

Starting with his educational background, an overview is given of the scientific activities of the late Klaus Dittrich as a Professor at the University of Leipzig. This includes in particular his work on furnace atomic absorption and emission. The application of these methods in studying the trace analysis of elements and molecules was Klaus Dittrich's major interest, but his activities also covered the application of lasers in elemental analaysis and the combination of various methods to form tandem procedures.

Optimization of atomization parameters in the speciation of organotin compounds by hydride generation–gas chromatography–electrothermal atomic absorption spectrometry

The detection of organotin hydrides by electrothermal (quartz furnace) atomic absorption spectrometry coupled on-line with hydride generation is closely dependent on several parameters such as the geometry of the quartz cell and the flow rates of additive gases. The influence of the design of the atomizer and the effects of the gas flow rates were evaluated in this study. The design of the quartz cell atomizer is not critical provided that a few rules are followed: the helium flow carrying organotin hydrides should be mixed with hydrogen in as small as possible dead volume (no mixing chamber) and oxygen introduction should be made as close as possible to the light path. The ratios of gas flow rates must be optimized for each cell design, the most important being the H2:O2 ratio chosen to produce highly reducing working conditions. Detection limits obtained after optimization ranged from 30 to 130 pg depending on the conditions and species.

Dynamic coating ion-interaction chromatographic separation of some trace impurities in oxygen-free electronic copper (OFEC) by pre-column chelation with 4-(2-thiazolylazo)resorcinol

Deleterious trace impurities like Mn, Fe, Co, Ni, Zn, Bi and Pb in oxygen-free electronic copper (OFEC) were separated and determined by dynamic coating ion-interaction chromatography (IIC) with spectrophotometric detection using pre-column reaction methods. 4-(2-Thiazolylazo)resorcinol (TAR) was used as pre-column chelating agent. The requirements for sample preparation and the conditions for pre-column chelation reaction are discussed. The optimum conditions for the sensitive detection of these trace metal ions after ion-chromatographic separation are set. The ph of the chelating medium and the eluent, the concentration of TAR and the composition of the eluent were investigated. The detection limits achieved were 2.0, 2.8, 0.6, 0.8, 1.2, 2.6 and 3.0 ng for Mn, Fe, Co, Ni, Zn, Bi and Pb, respectively. The results obtained by IIC methods compare well with those of graphite furnace atomic-absorption spectrometry and the certified values of Mur Bundy Hamil (MBH Analytical Ltd, U.K.).

Trace metal analyses in octocorals by microwave acid digestion and graphite furnace atomic-absorption spectrometry

Eight octocoral species from two reefs off the Venezuelan coast were analyzed to determine their Cd, Cu, Ni, Pb and Zn content. A microwave sample work-up procedure, including drying and acid digestion, was developed and found to be faster and more convenient than conventional methods. Accurate and precise results were obtained for the determination of the metals of interest, using graphite furnace atomic-absorption spectrometry (GFAAS) with L'vov platforms. The accuracy of the results was checked against synthetic standards prepared to simulate the matrix of the analyzed octocoral species. Standard deviation values for synthetically prepared standards were less than 1% in all cases. On the other hand, standard deviations for sample results were considerably higher due to heterogeneity of the samples and environmental conditions at the sampling sites.

Platform in furnace Zeeman-effect atomic absorption spectrometric determination of arsenic in beer by atomization of slurries of sample ash

A precise and accurate procedure is proposed for the determination of As in beer samples at the ng g–1 level by electrothermal atomic absorption spectrometry. The sensitivity of this technique is enhanced by a factor of 2.5 by introducing a preconcentration step, consisting of preliminary dry ashing of the samples and direct injection into the L'vov platform of a slurry of the ashes. The high background caused by the beer sample matrix is compensated for by the use of Zeeman correction. The arsenic is atomized under stabilized temperature platform furnace conditions with the addition of a nickel–ascorbic acid chemical modifier. The effect that each of these compounds has on the determination of As was studied, both separately and in combination. The methodology developed has a characteristic mass of 35 pg, which corresponds to a concentration of 0.7 ng of As per g of beer, a recovery of 102 ± 2% and a relative standard deviation of 4.5% for six independent analyses of a sample containing 8.5 ng g–1 of As. The accuracy of the method was confirmed by the analysis of a certified reference material sample. The proposed procedure was used to analyse real samples of beer and the results are comparable to those found by hydride generation atomic absorption spectrometry.

Determination of Nickel in Biological Samples by Electrothermal Atomization-Atomic Absorption Spectrometry Involving a Prior Extraction with 1,5-Bis (Di-2-Pyridylmethylene) Thiocarbono-Hydrazide

Abstract The use of 1,5-bis(di-2-pyridylmethylene) thiocarbono-hydrazide as a reagent for the extraction of Ni(II), Co(II), Zn(II), Fe(II), Cd(II) and Cu(II) into methyl isobutyl ketone has been studied, and a method for the determination of nickel at ultra-trace (ng/ml) level has been developed, by using electrothermal-atomization (graphite furnace) atomic absorption spectrometry involving a prior extraction with the cited extracting reagent. The chief advantage of the proposed method lies in its maximum allowed aqueous-to-organic phase volume ratio of 15. It has been successfully applied to the determination of nickel substrates in various biological samples.

Critical comparison of sources and detection methods in atomic spectrometry

Over the past three decades, the nature of atomic spectrometric analysis has changed dramatically. In the 1960's, flame and furnace atomic absorption were dominant, with furnace techniques gradually achieving prominence. In contrast, the 1970's witnessed the introduction of the inductively coupled plasma (ICP) and the direct current plasma (DCP). Although the ICP is still the most frequently used excitation source, the decade of the 1980's has seen a resurgence of interest in the glow-discharge lamp (GDL) and the microwave-induced plasma (MIP). Today, novel sources are continually being introduced, supported by combinations of gas mixtures and operated alternatively at DC, microwave or radio frequencies. These advances must be assessed against the backdrop of more unconventional atom-formation techniques that involve the use of high-powered lasers, rare-gas sputtering systems, or tandem (coupled) sources.

Recent advances in absolute analysis by graphite furnace atomicabsorption spectrometry

Some results are presented applying the STPF technique in GFAAS to the solution of the main problems obstructing progress toward absolute analysis, namely, elimination of matrix interferences, stabilization of calibration and theoretical calculation of sensitivity (characteristic masses, m 0). Recent advances in the calculation of the values of m 0 for 35 elements are discussed in detail. Compared with earlier publications, the present calculations make use of improved values of some physical constants (f,α,γ') and include the effects of the adjacent lines and Doppler line width in the light source. The largest discrepancy, always less than a factor of two between the calculation and experiment, is observed for Cs, Li and Rb, and is most probably due to partial ionization of the atoms. A study of the degree of ionization of Ba supports this assumption. The average value of m 0 cal/ m 0 exp for the remaining group of 32 elements was found to be 0.85 ± 0.10. No depressive effect was observed on the sensitivity of determination of the less volatile elements due to the spatial non-isothermality of the furnace. Theoretical calculations of the relative sensitivities in a.c. Zeeman AAS have been carried out. Satisfactory agreement was obtained with experiment.

A Study on the Nature of Boundary Lubricating Film: Analytical Method Development

The nature of the boundary lubricating film and its formation mechanism has been the subject of research in the last several decades. This study describes the development of a novel analytical technique designed specifically for the analysis of small amounts of lubricating film using an integrated size exclusion chromatography-refractive index-ultraviolet-graphite furnace atomic absorption (SECRI-UV-GFAA) system. Experiments under static simulation conditions as well as under dynamic rubbing conditions were conducted. Analysis of the reaction products in each case indicates the formation of high molecular weight organometallic compounds with molecular weights range from 1,000 to 100,000. This paper describes the methodology, equipment, and the procedures developed to measure nanogram quantities of the organometallic compounds generated by tribochemical reactions under boundary lubrication conditions.

Determination of sodium and potassium in nanoliter volumes of biological fluids by furnace atomic absorption spectrometry.

Renal tubular fluid samples are nanoliter (10/sup -9/ L) volumes containing sodium and potassium concentrations that are within the range of determination by furnace atomic absorption. Modification of nanoliter handling techniques and the use of microboats with the IL 951/655 provided a method for rapid precise analyses (relative standard deviation of 5%). Determinations of sodium and potassium were precise; however, inaccuracies occurred with anion substitution of sodium salts. NaHCO/sub 3/ solutions gave consistently higher peak height absorbance and area absorbance compared with those of NaCl: the peak area absorbance correlated linearly with the concentration of bicarbonate. Pretreatment of the microboat with boric acid eliminated this phenomenon and the associated inaccuracy. Comparison of determination of sodium in nanoliter samples by graphite furnace atomic absorption with macroanalysis by flame emission gave relative errors of less than 2.0%. Addition of sodium and potassium to tubular fluid samples yielded mean recoveries of 102.6% and 99.7%, respectively. The authors conclude that graphite furnace can be an accurate method for measurement of sodium and potassium in nanoliter volumes of biological fluids.

Accuracy in furnace atomic-absorption spectroscopy

Accuracy in furnace atomic-absorption spectroscopy

12] Atomic absorption spectrometry

Publisher Summary Atomic absorption methods are the most widely used for the determination of metals in biological materials. This chapter discusses an overview of the field to help in the selection among the available techniques. The various elements will then be treated with recommendations for preferred methodology. This chapter discusses the understanding that atomic absorption is two techniques: flame atomic absorption (AAS) and furnace AAS. Flame AAS is generally the best analytical technique available for samples that are most easily collected as solutions, if the analyte concentration is above the mg/liter range in the solution. Precision of about 1% is routinely obtained and better precision is available if extra care is taken in the preparation of standards and if slightly more time-consuming methods are used. There are several problems that stand in the way of increased utilization of furnace AAS for trace metal analyses. More importantly, many analysts fail to give adequate attention to the laboratory hygiene that is required at the very low levels accessible by furnace AAS.

Recent Instrumental Developments in the Background Correction Systems for Flame and Furnace Atomic Absorption

Abstract One of the problems that makes the use of the AA technique less frequent in some analytical fields is the interference of non-specific absorptions, particularly high in the furnace atomization. Traditional systems (used for several years for background correction with a deuterium arc lamp) are not applicable to some analyses, even if they meet most of the analytical needs. Some of the limits of this type of background correction are: Incorrect results in the presence of “structured” background. In this case, since the instrument carries on background determination to be substracted from the analytical wavelength measurement taking into account the average of the values within the monochromator bandpass, it can sometimes happen that the “background” to be substracted is over or under-estimated. Difficulty in the compensation at wavelengths over 420 nm. For some instruments, the problem is overtaken by mounting a tungsten lamp, that has the maximm emission energy in the visible region.

Distribution of Copper Among Components of Human Serum<xref ref-type="fn" rid="FN2">2</xref>

We examined the distribution of copper among four components of human serum separated by chromatography on Sephadex G-150 and Affi-gel blue. Analysis of copper by furnace atomic absorption indicated that normal adults have copper at an average of 600 ng/ml associated with ceruloplasmin; at 120 ng/ml with transcuprein, a new copper transport protein; at 150 ng/ml with albumin; and at 90 ng/ml with one to three components of low molecular weight (less than 30,000). Cancer patients had more total copper but similar proportions in the four serum fractions. In both groups, some individuals had very high levels of copper in transcuprein, albumin, and/or one or more components of the low-molecular-weight fraction. The results showed that, contrary to earlier conclusions, ceruloplasmin copper only comprised about 60% of the total in human serum; and not just ceruloplasmin but also other forms of serum copper may be elevated in cancer patients.

Precision Considerations in the Determination of Manganese in Mouse Brains by Furnace Atomic Absorption with Zeeman Background Correction

Abstract A method is presented for the determination of manganese in mouse brains by furnace atomic absorption with Zeeman background correction. Precision for the method of standard additions is compared with that of aqueous calibration curves. NBS bovine liver SRM is analyzed to verify the accuracy of the method.