Search results for "absorption spectroscopy"
showing 10 items of 828 documents
Interaction of diazepam with surfactants. Spectrophotometric and spectrofluorometric study
1986
Abstract The interaction of diazepam with non-ionic, anionic and cationic surfactants has been studied spectrophotometrically and fluorometrically. It has been verified that the absorption spectrum of diazepam is not modified in micellar medium. However, a dramatic five-fold increase in fluorescence sensitivity is observed in the presence of sodium lauryl sulphate (SDS). The experimental conditions, temperature, pH and surfactant concentration have been optimized to improve the fluorometric determination of diazepam and a detection limit of 0,04 ppmhas been obtained.
Direct determination of lead in human milk by electrothermal atomic absorption spectrometry
1999
Abstract Infants are particularly sensitive to the toxic effects of lead. Since milk is their only or main food it is important to know the contribution of milk to lead intake. The purpose of this study was to develop a direct method for determining the lead content of human milk by electrothermal atomic absorption spectrometry when a deuterium lamp is the only background correction available. The optimum conditions for lead determination in breast milk: sample dilution in Triton ×-100, modifier (75 μg of palladium) and nitric acid contents (2%) and the graphite furnace program (mineralization: 1100°C; atomization: 2300°C) were selected. The analytical parameters are: linearity (20–300 ng m…
Simultaneous determination of As, Cd, Cr and Pb in aqua regia digests of soils and sediments using electrothermal atomic absorption spectrometry and …
2002
A method was developed for the simultaneous multi-element determination of As, Cd, Cr and Pb in aqua regia digests of soils and sediments using an electrothermal atomic absorption spectrometer with a transversely heated graphite atomizer and longitudinal Zeeman-effect background correction. A fast furnace program with no pyrolysis stage or chemical modifier was used, and the total duration of the time-temperature program of the graphite furnace was 45 s. The method detection limits calculated from blank samples were 9.5 μg l−1, 0.18 μg l−1, 6.2 μg l−1 and 2.5 μg l−1 for As, Cd, Cr and Pb, respectively. Sample preparation procedures are briefly described. The accuracy of the method was confi…
Chromium speciation using activated alumina microcolumns and sequential injection analysis-flame atomic absorption spectrometry
2001
Abstract A new procedure has been developed for chromium speciation in water by sequential injection analysis and flame atomic absorption spectrometry. The method involves the online retention of Cr(VI) anionic species and Cr(III) cationic species on alumina microcolumns, prepared by packing activated alumina in polytetrafluoroethylene tubes, followed by selective elution of Cr(VI) with 2 mol l −1 NH 4 OH and of Cr(III) with 0.2 mol l −1 HNO 3 . Studies were carried out on the effect of retention and elution conditions for both Cr species. The limit of detection values, established as the concentration corresponding to three times the standard deviation of blank measurements divided by the …
Determination of mercury in dry-fish samples by microwave digestion and flow injection analysis system cold vapor atomic absorption spectrometry
1997
Abstract Flow injection analysis system cold vapor atomic absorption spectrometry (FIAS-CV-AAS) preceded by a wet digestion in a microwave oven, as a method for measuring mercury in fish was studied. The digestion process and conditions of the FIAS (carrier concentration: HCl 3% v v ; reducing agent: SnCl2 2% w v : filling and injection times: 8 and 25 min, respectively; and sample volumes) were optimized. The analytical parameters of the proposed method (detection limit = 7.7 ng/g; precision intraassay = 6.7%; interassay = 14.0%) demonstrates its adequacy and are similar to the ones (detection limit = 19.4 ng/g; precision intraassay = 11.2%; interassay = 15.9%) obtained using a conventiona…
High-frequency electrodeless discharge lamps for atomic absorption analysis
2003
Abstract In this paper we present the results of an investigation of high-frequency electrodeless discharge lamps (HFEDLs), containing Cd, Zn, Hg, As, Te, Se, Pb, Sn, Tl and Bi, developed in our laboratories as light sources for atomic absorption spectrometry (AAS). Important physical processes in the lamps are discussed. Essential characteristics of HFEDLs for AAS, such as intensity, stability and operating life are considered. The intensities and detection limits are compared with the corresponding characteristics of hollow cathode lamps. The temporal behavior of an As HFEDL is compared with that of a commercially available electrodeless discharge lamp. Detection limits in graphite furnac…
Flow injection flame atomic spectrometric determination of iron, calcium, magnesium, sodium and potassium in ceramic materials by using a variable-vo…
1993
A series of different ceramic materials, such as porcelain, feldspar, kaolin, varnish, clay and stoneware have been analyzed. Iron, calcium and magnesium have been determined in these materials by flame atomic absorption and sodium and potassium by flame emission. The use of a variable-volume injector enables one to carry out these analyses in a flow system (after fusion of samples with lithium metaborate) and does not require different dilutions for the determination of each type of sample considered, nor the use of different flow injection manifolds. The developed procedure provides a limit of detection of 100 μg/l for Na, 70 μg/l for Ca, 50 μg/l for both Fe and K and 8 μg/l for Mg. The c…
Atomic-absorption spectrometric determination of calcium, magnesium and potassium in leaf samples after decomposition with molten sodium hydroxide
1991
Abstract The decomposition of standard leaf samples of varied origin and nature by fusion with sodium hydroxide in an open system has been studied. The use of sodium nitrate as an auxiliary agent facilitated the mineralization of most of the samples. The solutions obtained were analysed for calcium, magnesium and potassium by flame atomic-absorption spectrometry. The method is fast and quite precise, with absolute standard deviations of 0.04–0.13, 0.002-0.03 and 0.04–0.12% for calcium, magnesium and potassium contents of O.8-5.0, 0.13–0.48 and 0.36–2.2% respectively. The limits of detection (μg/ml) in the determination step were 0.10 for calcium, 0.011 for magnesium, and 0.09 for potassium.
GFAAS determination of selenium in infant formulas using a microwave digestion method.
1994
A method for determining the selenium content of infant formulas is proposed. It includes wet digestion with nitric acid and hydrogen peroxide in medium pressure teflon bombs in a microwave oven and determination by graphite furnace atomic absorption spectrometry (GFAAS). The absence of interferences is checked. Values obtained for the limit of detection (19.4 ng/g), precision (RSD = 2.2%) and accuracy by analysis of a reference material show that the method is reliable.
Indirect Determination of Cyanide by Atomic Absorption Spectrometry
1995
Abstract Two methods for determination of cyanide by atomic absorption spectrometry (AAS) are developed. Both methods are based on the formation of an ion association compound between a metal complex, (Ag(CN)2 − or Cu(CN)3 2-), and a quaternary ammonium ion (benzyldimethylhexadecylammonium ion). The ion association compound is extracted into isomethylbutylketone (IBMK) and the metal is determined by AAS directly in extract. The method based on the formation of silver cyanide complex provides a reproducibility of 2.5%, a recovery of 99% and a detection limit of 1.7 μg/L while the method based on the formation of copper complex gives a reproducibility of 6%, a recovery of 93% and a detection …