Additive analysis atomic absorption spectroscopy

A reasonably complete analysis of the inorganic chemical composition of the aerosol requires much effort and involves, in addition to wet chemical methods, instrumental techniques such as neutron activation analysis, atomic absorption spectroscopy, or proton-induced X-ray emission (PIXE). These latter techniques yield the elemental composition. They furnish no direct information on the chemical compounds involved, although auxiliary data from mineralogy, chemical equilibria, etc. usually leave little doubt about the chemical form in which the elements occur. Thus, sulfur is present predominantly as sulfate, and chlorine and bromine as Cl- and Br-, respectively, whereas sodium potassium, magnesium, and calcium show up as... 

In addition to the spark emission methods, quantitative analysis directly on soHds can be accompHshed using x-ray fluorescence, or, after sample dissolution, accurate analyses can be made using plasma emission or atomic absorption spectroscopy (37). 

Two colorimetric methods are recommended for boron analysis. One is the curcumin method, where the sample is acidified and evaporated after addition of curcumin reagent. A red product called rosocyanine remains it is dissolved in 95 wt % ethanol and measured photometrically. Nitrate concentrations >20 mg/L interfere with this method. Another colorimetric method is based upon the reaction between boron and carminic acid in concentrated sulfuric acid to form a bluish-red or blue product. Boron concentrations can also be deterrnined by atomic absorption spectroscopy with a nitrous oxide—acetjiene flame or graphite furnace. Atomic emission with an argon plasma source can also be used for boron measurement. 

Atomic absorption spectroscopy of VPD solutions (VPD-AAS) and instrumental neutron activation analysis (INAA) offer similar detection limits for metallic impurities with silicon substrates. The main advantage of TXRF, compared to VPD-AAS, is its multielement capability AAS is a sequential technique that requires a specific lamp to detect each element. Furthermore, the problem of blank values is of little importance with TXRF because no handling of the analytical solution is involved. On the other hand, adequately sensitive detection of sodium is possible only by using VPD-AAS. INAA is basically a bulk analysis technique, while TXRF is sensitive only to the surface. In addition, TXRF is fast, with an typical analysis time of 1000 s turn-around times for INAA are on the order of weeks. Gallium arsenide surfaces can be analyzed neither by AAS nor by INAA. 

Quantitative analysis in flame atomic absorption spectroscopy utilizes Beer s law. The standard curve is a Beer s law plot, a plot of absorbance vs. concentration. The usual procedure, as with other quantitative instrumental methods, is to prepare a series of standard solutions over a concentration range suitable for the samples being analyzed, i.e., such that the expected sample concentrations are within the range established by the standards. The standards and the samples are then aspirated into the flame and the absorbances read from the instrument The Beer s law plot will reveal the useful linear range and the concentrations of the sample solutions. In addition, information on useful linear ranges is often available for individual elements and instrument conditions from manufacturers and other literature. 

The minor and trace elements in coals are currently determined by several techniques, the most popular of which are optical emission and atomic absorption spectroscopy. Neutron activation analysis is also an excellent technique for determining many elements, but it requires a neutron source, usually an atomic reactor. In addition, x-ray fluorescence spectroscopy, electron spectroscopy for chemical analyses (ESCA), and spark source mass spectroscopy have been successfully applied to the analyses of some minor and trace elements in coal. 

Multielement analysis will become more important in industrial hygiene analysis as the number of elements per sample and the numbers of samples increases. Additional requirements that will push development of atomic absorption techniques and may encourage the use of new techniques are lower detction and sample speciation. Sample speciation will probably require the use of a chromatographic technique coupled to the spectroscopic instrumentation as an elemental detector. This type of instrumental marriage will not be seen in routine analysis. The use of Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) (17), Zeeman-effect atomic absorption spectroscopy (ZAA) (18), and X-ray fluorescence (XRF) (19) will increase in industrial hygiene laboratories because they each offer advantages or detection that AAS does not. 

Technical examination of objects coated with a protective covering derived from the sap of a shrubby tree produces information that can be used to determine the materials and methods of manufacture. This information sometimes indicates when and where the piece was made. This chapter is intended to present a brief review of the raw material urushi, and the history and study of its use. Analytical techniques have included atomic absorption spectroscopy, thin layer chromatography, differential thermal analysis, emission spectroscopy, x-ray radiography, and optical and scanning electron microscopy these methods and results are reviewed. In addition, new methods are reported, including the use of energy dispensive x-ray fluorescence, scanning photoacoustical microscopy, laser microprobe and nondestructive IR spectrophotometry. 

The standard addition method is commonly used in quantitative analysis with ion-sensitive electrodes and in atomic absorption spectroscopy. In TLC this method was used by Klaus 92). Linear calibration with R(m=o)=o must also apply for this method. However, there is no advantage compared with the external standard method even worse there is a loss in precision by error propagation. The attainable precision is not satisfactory and only in the order of 3-5 %, compared to 0.3-0.5 % using the internal standard method 93). 

The characterisation of the colloids both in the free and in the embedded state was first performed using transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and atomic absorption spectroscopy (AAS). In addition, nitrogen adsorption-desorption curves at 77 K, H2-chemisorption measurements, solid state Si-NMR, XRD, SAXS, XPS, MAS-NMR, NH3-FTIR, and Au Mossbauer spectroscopy were applied. For the embedded triflates, the catalysts were characterized by nitrogen adsorption-desorption isotherms at 77K, TG-DTA, H, C, and Si solid state MAS-NMR, XRD, TEM, SEM, XPS and, FTIR after adsorption of NH3. 

Finally, it is recommended that for inductively coupled plasma (ICP) analysis a final filtration (0.45 xm) is carried out in order to prevent nebulizer blockages. If graphite-furnace atomic absorption spectroscopy (GFAAS) is the method of analysis, it is recommended that the standard additions method of calibration is used (see Chapter 1). 

Sodium and potassium levels are difficult to analyze by titrimetric or colorimetric techniques but are among the elements most easily determined by atomic spectroscopy (2,38) (Table 2). Their analysis is important for the control of infusion and dialysis solutions, which must be carefully monitored to maintain proper electrolyte balance. Flame emission spectroscopy is the simplest and least expensive technique for this purpose, although the precision of the measurement may be improved by employing atomic absorption spectroscopy. Both methods are approved by the U.S. (39), British (40), and European (41) Pharmacopeias and are commonly utilized. Sensitivity is of no concern, due to the high concentrations in these solutions furthermore, dilution of the sample is often necessary in order to reduce the metal concentrations to the range where linear instmmental response can be achieved. Fortunately, the analysis may be carried but without additional sample preparation because other components, such as dextrose, do not interfere. 

Oscilloscope traces obtained from a 10 3M Ph2C-0 solution are displayed in Fig. 7.4. In catalyst-free solution, the 550-nm absorption of the ketyl decays as expected according to a second-order rate law. The rate constant obtained from the kinetic analysis if 8.5 x 10sM-1s 1 in agreement with published literature values. At the low laser intensity applied, this decay is barely visible on the 10-/is/division time scale in Fig. 7.4 a. Addition of catalyst, 8 mg of Pt/100 ml of solution as determined by atomic absorption spectroscopy, sharply enhances the absorption decay. This process follows approximately first-order kinetics, the half-life time being 40 /is. The decay is attributed to the reaction... 

The differential pulse and square wave techniques are among the most sensitive means for the direct evaluation of concentrations, and they find wide use for trace analysis. When they can be applied, they are often far more sensitive than molecular or atomic absorption spectroscopy or most chromatographic approaches. In addition, they can provide information about the chemical form in which an analyte appears. Oxidation states can be defined, complexation can often be detected, and acid-base chemistry can be characterized. This information is frequently overlooked in competing methods. The chief weakness of pulse analysis, common to most electroanalytical techniques, is a limited ability to resolve complex systems. Moreover, analysis time can be fairly long, particularly if deaeration is required. 

From a historical point of view, the analysis of food is performed predominandy using typical chemical or physicochemical methods. These are, for example, wet chemical methods for proximity analysis or chromatographic methods for the analysis of pesticides and veterinary dmg residues. In addition, food chemists use such physics-based methods as viscosity measurement and atomic absorption spectroscopy for the analysis of heavy metals. 

Quantitative Analysis learning to use the WinLab software for furnace atomic absorption spectroscopy calibration based on standard addition no write-up required... 

The most common method of analytical determination of rubidium is atomic absorption spectroscopy (AAS) or neutron activation analysis (NAA). Chemical methods of analysis for the determination of rubidium are difficult because of the tedious procedures required to effect the separation from the other alkali metals. The beneficial effects of the addition of other alkali metals, particularly potassium, sodium, and cesium, added to interfere with the ionization of rubidium is detailed by many authors [39,53-55]. Recent evaluation of the benefits of these ions in the determination of rubidium in human erythrocytes has concluded that erythrocytes should be diluted 1 50 with potassium to give a final potassium concentration of 10000 ppm. Under these conditions, the sensitivity of absorbance was increased about threefold and rubidium concentrations could be determined in the range 0-60 ppm [56]. 

Both infrared and Raman spectroscopy are extremely powerful analytical techniques for both qualitative and quantitative analysis. However, neither technique should be used in isolation, since other analytical methods may yield important complementary and/or confirmatory information regarding the sample. Even simple chemical tests and elemental analysis should not be overlooked and techniques such as chromatography, thermal analysis, nuclear magnetic resonance, atomic absorption spectroscopy, mass spectroscopy, ultraviolet and visible spectroscopy, etc., may all result in useful, corroborative, additional information being obtained. 

A review of many types of instrumental analysis used for the characterization of gunshot residues has appeared recently. This includes descriptions of the use of atomic absorption spectroscopy, neutron activation analysis and X-ray fluorescence as well as various mass spectrometry techniques after preconcentration of analytes using separation methods such as HPLC and capillary electrophoresis. In addition, atomic absorption spectroscopy has been used to characterize the brass used in different production lots of cartridge cases. 

A recent review by Balaram gives an account of the various instrumental techniques used in geological analysis. These include atomic absorption spectroscopy and inductively coupled plasma atomic emission spectroscopy as well as X-ray fluorescence, isotope dilution mass spectrometry and neutron activation analysis in addition to recent developments in inductively coupled plasma mass spectrometry especially in rare earth element analysis. 

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