Atomic absorption spectrophotometry AAS

Metal Content. Two common analytical methods for determining metal content are by titration and by atomic absorption spectrophotometry (aas). The titration method is a complexiometric procedure utilizing the disodium salts of ethylenediaminetetraacetic acid (EDTA). The solvent, indicator. 

Further techniques which may be applied directly to the solvent extract are flame spectrophotometry and atomic absorption spectrophotometry (AAS).13 The direct use of the solvent extract in AAS may be advantageous since the presence of the organic solvent generally enhances the sensitivity of the method. However, the two main reasons for including a chemical separation in the preparation of a sample for AAS are ... 

Sediment pollution. The concentrations of pollutants in the dated sediment cores have been determined in our laboratory by atomic absorption spectrophotometry (AAS). Donazzolo et al. (15) and Pavoni et al. (16) reported mainly heavy metal concentrations. Marcomini et al. (17) and Pavoni et al. (18) discussed the concentration profiles of organic pollutants such as chlorinated hydrocarbons and polycyclic aromatic hydrocarbons. 

Analytical Procedures. Mn was determined by atomic absorption spectrophotometry (AAS) or the formaldioxime method (27J. Ca, Mg and Fe were determined by AAS. Silicate, phosphate, sulphate and chloride were determined using techniques described in Standard Methods (28). The molybdosi1icate method was used for silicate. Phosphate was determined using the vanadomolybdophosphoric acid method. Sulphate was determined by BaSO gravimetry. Chloride was determined by the mercuric chloride method. Salicylate and phthalate were determined by UV spectrophotometry. 

Different methods have different detection limits. For example, the flame atomic absorption spectrophotometry (AAS) method for aluminum has a detection limit of 30 parts per million, while the inductively coupled plasma... 

Analysis of both soil and road dust for Al, Si, K, Ti, and Fe was performed at the Illinois State Geological Survey, using X-ray fluorescence techniques (O. Ca and K were determined at the Water Survey by atomic absorption spectrophotometry (AAS) following LIBO3 fusion to disolve the sample ). 

Graphite furnace atomic absorption spectrophotometry (AAS) has been shown to be a versatile technique for the detection of low levels of tin, reproducibly over a wide linear working range and was the method of analysis used in this study (10,11). 

The GECE sensors were used for lead determination in real water samples suspected to be contaminated with lead obtained from water suppliers. The same samples were previously measured by three other methods a potentiometric FIA system with a lead ion-selective-electrode as detector (Pb-ISE) graphite furnace atomic absorption spectrophotometry (AAS) inductively coupled plasma spectroscopy (ICP). The results obtained for lead determination are presented in Table 7.1. The accumulation times are given for each measured sample in the case of DPASV. Calibration plots were used to determine the lead concentration. GEC electrode results were compared with each of the above methods by using paired -Test. The results obtained show that the differences between the results of GECE compared to other methods were not significant. The improvement of the reproducibility of the methods is one of the most important issues in the future research of these materials. 

Table 7.1 shows the results obtained along with those given by using the graphite furnace atomic absorption spectrophotometry (AAS). 

All raw and treated coals were analyzed at Ames Laboratory for trace, major, and minor elements using energy-dispersive x-ray fluorescence (XRF), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and atomic absorption spectrophotometry (AA). General analytical procedures employed for each of these techniques are discussed separately below. 

Trace element analysis of foods can be carried out to check for contamination by toxic elements, such as lead and cadmium, or to determine beneficial micronutrients, or as an aid to distinguishing geographical origin. In fats, small numbers of trace elements are measured after digestion of the sample in acid followed atomic absorption spectrophotometry (AAS) or by direct graphite furnace vaporization. An AAS procedure for measuring lead in edible oils and fats has been collaboratively trialed with cocoa butter as a test material (Firestone, 1994). 

Atomic absorption spectrophotometry (AAS) is one of the most widely used methods. Either flame atomisation or electrothermal atomisation (ETA) using the graphite furnace is employed. Some useful references are given in the Bibliography. 

The remaining cations were analyzed by atomic absorption spectrophotometry (AAS) except ferrous iron which was done by a modification of the Ferrozine method (29, 30, 3j ). Total iron was determined by AAS and Fe " by difference. Sulfate was... 

Sample analysis by thermal ionization mass spectrometry (TIMS) results in measurement of isotopic ratios of minerals. Total mineral content of samples is then determined by one of two methods. One approach is to use flame atomic absorption spectrophotometry (AAS) to determine total mineral content of samples. Since AAS does not have the same level of precision as TIMS a sufficient number of replicates is analyzed for a mineral content determination with a CV of within 1%. Alternatively if a mineral has 3 or more isotopes and fractionation corrections are not made the following procedure may be used. An individual is fed one isotope and another isotope is added to the sample prior to analysis to determine the total mineral content of the sample by dilution of the second isotope. In this way both the amount of the isotope fed which is recovered in the feces and the total mineral content of the sample can be determined simultaneously. If fractionation corrections are to be made a mineral must have at least four isotopes. Details of these procedures will be reported separately. 

The catalyst was NH4Y, obtained by repeated ammonium exchange of NaY. Analysis by atomic absorption spectrophotometry (AAS) provided the formula (NH4)54.6 Nao.25 AI55.1 Sii37 O384. 

Sodium may be determined by atomic absorption spectrophotometry (AAS), flame emission spectrophotometry (FES), electrochemically with an Na -ISE, or spectrophoto-metrically. Of these methods, ISE methods are by far the most common. Excellent accuracy and coefficients of variation of less than 1.5% are readily achieved with modern equipment, reliable calibrators, and a good quality assurance program. Because sodium and potassium are routinely assayed together, methods for their analysis are described together later in this chapter. 

Analytical techniques used for clinical trace metal analysis include photometry, atomic absorption spectrophotometry (AAS), inductively coupled plasma optical emission (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS). Other techniques, such as neutron activation analysis (NAA) and x-ray fluorescence (XRF), and electrochemical methods, such as anodic stripping voltammetry (ASV), are used less commonly For example. NAA requires a nuclear irradiation facility and is not readily available and ASV requires completely mineralized solutions for analysis, which is a time-consuming process. 

Atomic Absorption Spectrometry Methods The National Committee for Clinical Laboratory Standards (NCCLS) has approved a method using atomic absorption spectrophotometry (AAS) as a reference method for measuring total serum calcium. This method has been compared with isotope dilution-mass spectrometry (ID-MS), the definitive method for total serum calcium developed by the National Institute of Standards and Technology. The reference method is reported to have an accuracy of 100 2%, compared with 100 0.2% for ID-MS. Although AAS can provide better accuracy and precision for total serum calcium than the widely used photometric methods, it is used by only a few laboratories. It should continue to be used for validating new total calcium methods. 

F, lignin 5 minutes), boiling Cl hr. in a boiling water bath), and incubation for 2h hours at 30°C which served as the control. Samples were filtered and the residue together with the filter paper was digested with concentrated HC1 for 10 minutes, then cooled and filtered. The filtrates were analyzed via atomic absorption spectrophotometry (AAS)for soluble metal content. 

The following replicate calcium determinations on a blood sample using atomic absorption spectrophotometry (AAS) and a new colorimetric method were reported. Is there a significant difference in the precision of the two methods ... 

A technique closely related to flame emission spectrometry is atomic absorption spectrophotometry (AAS) because they each use a flame as the atomizer. We discuss here the factors affecting absorption and because of the close relationship of atomic absorption and flame photometry, we shall make comparisons between the two techniques where appropriate. 

Aerosediment samples were continuously collected in the Kikinda and Novi Sad areas, at different sites, for the period from 1994 to 1997. In this period, 194 samples were collected in the Kikinda area and 703 samples were collected in the Novi Sad area. Each sample was collected for 30 days following a standard sediment sampling method. Cadmium concentrations were determined using atomic absorption spectrophotometry (AAS) on a graphite furnace and expressed as mean monthly values in p,g/ m per day (WHO, 1987). 

The adsorption properties of Amberlite XAD4 resins as adsorbents suitable for multielement preconcentration of complexes of 15 elements with different chelate-forming reagents from aqueous solutions have been extensively investigated by Yang and Jackwerth [129,130]. Adsorbed trace compounds can easily be eluted from the resin by use of 1 M HNOj in acetone and subsequently determined by atomic absorption spectrophotometry (AAS). Besides multielement preconcentration, selective trace separation procedures are possible by suitable selection of the complexing reagents and pH adjustment of the sample solution. 

Chemical analysis of hazardous substances in air, water, soil, sediment, or solid waste can best be performed by instrumental techniques involving gas chromatography (GC), high-performance liquid chromatography (HPLC), GC/mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR), and atomic absorption spectrophotometry (AA) (for the metals). GC techniques using a flame ionization detector (FID) or electron-capture detector (BCD) are widely used. Other detectors can be used for specific analyses. However, for unknown substances, identification by GC is extremely difficult. The number of pollutants listed by the U.S. Environmental Protection Agency (EPA) are only in the hundreds — in comparison with the thousands of harmful... 

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