Atomic absorption parameters

The atomic absorption parameters were lamp current, 8 mA high voltage 350 d.c. slit width, 50 m absorption wavelength, 283.3 nm. 

I have carried out widespread studies on the application of a sensitive and selective preconcentration method for the determination of trace a mounts of nickel by atomic absorption spectrometry. The method is based on soi ption of Cu(II) ions on natural Analcime Zeolit column modified with a new Schiff base 5-((4-hexaoxyphenylazo)-N-(n-hexyl-aminophenyl)) Salicylaldimine and then eluted with O.IM EDTA and determination by EAAS. Various parameters such as the effect of pH, flow rate, type and minimum amount of stripping and the effects of various cationic interferences on the recovery of ions were studied in the present work. 

On the basis of data obtained the possibility of substrates distribution and their D-values prediction using the regressions which consider the hydrophobicity and stmcture of amines was investigated. The hydrophobicity of amines was estimated by the distribution coefficient value in the water-octanole system (Ig P). The molecular structure of aromatic amines was characterized by the first-order molecular connectivity indexes ( x)- H was shown the independent and cooperative influence of the Ig P and parameters of amines on their distribution. Evidently, this fact demonstrates the host-guest phenomenon which is inherent to the organized media. The obtained in the research data were used for optimization of the conditions of micellar-extraction preconcentrating of metal ions with amines into the NS-rich phase with the following determination by atomic-absorption method. 

Inadequate regulation of atomizer temperature Is a major source of Imprecision In electrothermal atomic absorption spectrometry. The programmed heating of electrothermal atomizers can be achieved by five different methods, depending upon the electrical or physical parameters which are monltorled during... 

Atomic absorption spectrometry 12.14 Oxygen demand parameters... 

We have spoken frequently in this chapter about sensitivity and detection limit in reference to advantages and disadvantages of the various techniques. Sensitivity and detection limit have specific definitions in atomic absorption. Sensitivity is defined as the concentration of an element that will produce an absorption of 1% (absorptivity percent transmittance of 99%). It is the smallest concentration that can be determined with a reasonable degree of precision. Detection limit is the concentration that gives a readout level that is double the electrical noise level inherent in the baseline. It is a qualitative parameter in the sense that it is the minimum concentration that can be detected, but not precisely determined, like a blip that is barely seen compared to the electrical noise on the baseline. It would tell the analyst that the element is present, but not necessarily at a precisely determinable concentration level. A comparison of detection limits for several elements for the more popular techniques is given in Table 9.2. 

Example The intensity of atomic absorption lines for the alkali metals, such as potassium (K) rubidium (Rb) and caesium (Cs), is found to be affected by temperature in a complex way. Under certain experimental parameters a noticeable decrease in absorption may be observed in hotter flames. Hence, lower excitation temperatures are invariably recommended for the analysis of alkali metals. 

The values of solutions were adjusted with 0.1 mol/L NH OH or HNOj and measured with Metrohm Herisau E510 pH meter. A magnetic stirrer model Arex was used for stirring the adsorption batches. The concentration of solution before and after adsorption was measured by using Atomic Absorption Spectrometer (AAS) Analytika Jena. All the measurements were made under optimization of the below mentioned parameters. 

Instrumentation. A Varian Model 63 atomic absorption spectrophotometer, equipped with a graphite atomizer head was used to analyze all samples. Instrument parameters appear in Table I. A tin, hollow cathode lamp was used to generate the desired wavelength. A deuterium arc lamp was used to correct for non-atomic absorption signals. 

To effect this measurement the slit bandwidth of the atomic absorption apparatus is 1 nm. What does this parameter represent ... 

J. Y. Cabon, Influence of Experimental Parameters on the Determination of Antimony in Seawater by Atomic Absorption Spectrometry, Anal. Bioarud. Chem. 2003,374, 1282. 

There is some evidence that localized copper imbalance is related to rheumatoid arthritis (RA) conditions. Low molecular weight copper complex concentrations in plasma and synovial fluids are increased as part of the body s natural response to RA. Secondly, when such increases are induced by copper administration, they have a powerful antiinflammatory effect. More data are required to show the medical significance of these changes. Three parameters which should be reported are (i) total copper levels (by atomic absorption spectrophotometry) (ii) total ceruloplasmin levels (by autoimmune assay) and (iii) the relative molecular weight distribution (by Sephadex gel filtration and ultrafiltration). 

Problems in the direct determination of cadmium in soil extracts by graphite furnace atomic absorption spectrometry are overcome by the use of a low atomisation temperature of 1200 °C (mini-furnace or high heating rate of > 2000 °C/s), the addition of molybdenum, hydrogen peroxide and nitric acid as a matrix modifier, and accurate optimisation of the instrumental parameters. 

HPLC units have been interfaced with a wide range of detection techniques (e.g. spectrophotometry, fluorimetry, refractive index measurement, voltammetry and conductance) but most of them only provide elution rate information. As with other forms of chromatography, for component identification, the retention parameters have to be compared with the behaviour of known chemical species. For organo-metallic species element-specific detectors (such as spectrometers which measure atomic absorption, atomic emission and atomic fluorescence) have proved quite useful. The state-of-the-art HPLC detection system is an inductively coupled plasma/MS unit. HPLC applications (in speciation studies) include determination of metal alkyls and aryls in oils, separation of soluble species of higher molecular weight, and separation of As111, Asv, mono-, di- and trimethyl arsonic acids. There are also procedures for separating mixtures of oxyanions of N, S or P. 

The wavelengths at which absorption or emission spectral peaks occur are characteristics of the particular atom or molecule giving rise to the peaks, and thus may be used for qualitative identification. In quantitative instrumental methods of analytical chemistry, we try to measure some property of atoms or molecules which varies linearly with the concentration of the species of interest. What parameter should we measure if we wish to exploit atomic absorption ... 

The optimization of the atomic absorption method of determining metals in particulates found in the air of workplace is described. The Plackett-Burman Youden-Steiner balanced incomplete block designs as well as single-factor experiments were utilized with ten metals Be, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, and Pd. Of the parameters tested, perchloric acid digestion, flame-stoichiometry, and the composition of the calibration standards were the most significant. Perchloric acid affected the recoveries of chromium. This was attributed to the formation of volatile chromylchloride. Flame-related phenomena and interelemental effects were brought under control using lanthanum flame buffer. 

A preliminary knowledge of the crystal structure is important prior to a detailed charge density analysis. Direct methods are commonly used to solve structures in the spherical atom approximation. The most popular code is the Shelx from Sheldrick [26] which provides excellent graphical tools for visualization. The refinement of the atom positional parameters and anisotropic temperature factors are carried out by applying the full-matrix least-squares method on a data corrected if found necessary, for absorption and diffuse scattering. Hydrogen atoms are either fixed at idealized positions or located using the difference Fourier technique. 

Procedure Concomitantly determine the absorbance of each Standard Preparation and of the Sample Preparation at 422.7 nm, with a suitable atomic absorption spectrophotometer, following the operating parameters as recommended by the manufacturer of the instrument. Plot the absorbance of the Standard Preparations versus concentration of calcium, in micrograms per milliliter, and from the curve so obtained determine the concentration, C, in micrograms per milliliter, of calcium in the Sample Preparation. Calculate the quantity, in milligrams, of calcium in the sample taken by the formula... 

Apparatus Use a suitable atomic absorption spectrophotometer (Perkin-Elmer Model 3100 or equivalent) fitted with a graphite furnace (Perkin-Elmer HGA 600 or equivalent). Use a lead hollow-cathode lamp (Perkin-Elmer or equivalent) with argon as the carrier gas. Follow the manufacturers directions for setting the appropriate instmment parameters for lead determination. 

Instrumental parameters in the determination of rare earth elements by graphite-furnace atomic-absorption... 

In addition to the normal requirements of a good atomic absorption spectrometer two parameters are of paramount importance when employing a furnace as the atomising source. These> are (a) the response time of the signal handling circuitry must be sufficiently rapid to capture the transient absorption signals which are characteristic of furnace atomisers, and (b) the... 

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