Metals, determination atomic absorption spectrometr

The alkah metals are commonly separated from all other elements except chlorine before gravimetric determination. In the absence of other alkaUes, sodium maybe weighed as the chloride or converted to the sulfate and weighed. WeU-known gravimetric procedures employ precipitation as the uranyl acetate of sodium—2inc or sodium—magnesium. Quantitative determination of sodium without separation is frequently possible by emission or atomic-absorption spectrometric techniques. 

In order to overcome the problem of the high nonspecific absorption, alternative procedures have been tested, which involve prior separation of the trace metals from the salt matrix. Examples of extraction of trace metals from seawater as chelates with subsequent determination by electrothermal atomic absorption spectrometric procedures have been described [381,382], but these and similar methods are seldom effective and satisfactory when the matrix is very complex and the analyte concentration very low. 

Brief mention has been made, particularly in connection with the inductively coupled plasma atomic absorption spectrometric technique, of the need to preconcentrate seawater samples prior to the determination of metals, in order to achieve adequate detection limits. 

Ti, or PEEK (polyether ether ketone) to allow measurements under very corrosive conditions. The separated phases pass AMX gadgets for on-line detection (radiometric, spectrophotometric, etc.) or phase sampling for external measurements (atomic absorption, spectrometric, etc.), depending on the system studied. The aqueous phase is also provided with cells for pH measurement, redox control (e.g., by reduction cells using platinum black and hydrogen, metal ion determination, etc.) and temperature control (thermocouples). 

The dissolution and measurement experiments start with attempts to dissolve a sample (300 yg or less) of a metal or metal compound species using the prescribed NIOSH procedure, followed by measurement using the NIOSH atomic absorption spectrometric (AAS) procedure. If 90 percent recovery of the metal is not achieved, the dissolution procedure is modified, or changed completely, to achieve 90 percent recovery. From previous studies, it is expected that the metal oxides, and selenium generally, would pose problems. The NIOSH-AAS procedures are to be evaluated also, especially when the dissolution matrix is changed. The AAS detection limits using standards are determined through the measurement of blanks. 

Background Caused by Filters. Since all of the particles were collected on membrane filters it was necessary to determine the blank metal concentrations in the filter. This enabled an estimation of how many particles must be collected in order that the levels of the metals were significantly greater than the blank filter. For this study, both neutron and flame atomic absorption spectrometric analyses were used and the results are shown in Table I. The analyses by neutron activation were made on the filter directly whereas those by atomic absorption spectrometry were obtained by extracting the filter with nitric acid (16M Ultrex). There are apparent differences between the two sizes of membrane filters which are probably related to the fact that these filter sets were obtained at different times. Also, while the metal blanks within a particular batch of filters vary by negligible amoimts, the variations between batches are considerable. These determinations are near the detection limits for both techniques, and therefore there are considerable uncertainties associated with the results. However, these blanks did indicate the minimum level of metals which must be collected if the analyses are to be significant. 

Mousty F, Omenetto N, Pietra R, et al. 1984. Atomic-absorption spectrometric, neutron-activation and radioanalytical techniques for the determination of trace metals in environmental, biochemical and toxicological research. Part I. Vanadium. Analyst 109 1451-1454. 

But there is no specific FAAS standard method specially evaluated or approved for polluted soil samples there is the EPA methods (SW-846 EPA (2000)) or one ISO standard (ISO 11047). This standard is connected with the determination of several metals in aqua regia extracts. It provides a method for the determination of Cd, Cu, Co, Pb, Mn, Ni and Zn by flame and electrothermal atomic absorption spectrometric methods. 

Udoh AP (2000) Atomic absorption spectrometric determination of calcium and other metallic dements in some animal protein sources. Talanta 52 749-754. 

Z. Fang, S. Xu, and S. Zhang, The Determination of Trace Amounts of Heavy Metals in Waters by a Flow-Injection System Including Ion-Exchange Preconcentration and Flame Atomic Absorption Spectrometric Detection. Anal. Chim. Acta, 164 (1984) 41. 

A sewage contaminated calcareous soil was selected from the bank of reference materials of the Environment Institute of the Joint Research Centre of Ispra (Italy) in order to present both the characteristics of a calcareous soil (CaCOs content of 228 g kg ) and with heavy metal content well above the determination limits of the currently used flame atomic absorption spectrometric method. The soil sample was composed of 15.4% sand (2 mm to 50 mm), 9.3% coarse silt (50 to 20 pm), 34.0% fine silt (20 to 2 pm) and 41.3% clay (<2 pm). 

Electrothermal Atomic Absorption Spectrometric Determination of Trace Metals in Sea Water with On-line Sorbent Extraction Separation and Preconcentration [10,16]... 

FIA analyzers or FIA components. One company produces a series of instruments that are flow injection systems with atomic absorption spectrometric detection dedicated to determination of mercury. Some companies produce flow injection analyzers for a large number of ions. One supplier has an analyzer that comprises three separate units a basic analytical module, an automatic sample module, and a data capture module, all these units being completely automated. The instrument is capable of analyzing nutrients, ions, and metals. It offers a wide analytical choice using ion-selective electrodes (ISEs), chemiluminescence, or fluorescence. With analysis speeds up to 120 samples per hour and detection limits down to parts per billion levels, this flow injection analyzer performs determinations well compared with other techniques. 

Applications Atomic Absorption Spectrometric Determination of Metals... 

M. Soylak, S. Saracoglu, U. Divrikli, and L. Elci. Coprecipitation of heavy metals with erbium hydroxide for their flame atomic absorption spectrometric determinations in envirorunental samples. Talanta 66 1098-1102, 2005. 

Tiizen, M., Sari, H., Soylak, M., 2004. Microwave and wet digestion procedures for atomic absorption spectrometric determination of trace metals contents of sediment samples. Anal. Lett. 37, 1925-1936. 

Rousselet E and Thuillier F (1979) Atomic absorption spectrometric determination of metallic elements in... 

Common gas chromatographic detectors that are not element- or metal-specific, atomic absorption and atomic emission detectors that are element-specific, and mass spectrometric detectors have all been used with the hydride systems. Flame atomic absorption and emission spectrometers do not have sufficiently low detection limits to be useful for trace element work. Atomic fluorescence [37] and molecular flame emission [38-40] were used by a few investigators only. The most frequently employed detectors are based on microwave-induced plasma emission, helium glow discharges, and quartz tube atomizers with atomic absorption spectrometers. A review of such systems as applied to the determination of arsenic, associated with an extensive bibliography, is available in the literature [36]. In addition, a continuous hydride generation system was coupled to a direct-current plasma emission spectrometer for the determination of arsenite, arsenate, and total arsenic in water and tuna fish samples [41]. 

Mykytiuk et al. [184] have described a stable isotope dilution sparksource mass spectrometric method for the determination of cadmium, zinc, copper, nickel, lead, uranium, and iron in seawater, and have compared results with those obtained by graphite furnace atomic absorption spectrometry and inductively coupled plasma emission spectrometry. These workers found that to achieve the required sensitivity it was necessary to preconcentrate elements in the seawater using Chelex 100 [121] followed by evaporation of the desorbed metal concentrate onto a graphite or silver electrode for isotope dilution mass spectrometry. 

A convenient method is the spectrometric determination of Li in aqueous solution by atomic absorption spectrometry (AAS), using an acetylene flame—the most common technique for this analyte. The instrument has an emission lamp containing Li, and one of the spectral lines of the emission spectrum is chosen, according to the concentration of the sample, as shown in Table 2. The solution is fed by a nebuhzer into the flame and the absorption caused by the Li atoms in the sample is recorded and converted to a concentration aided by a calibration standard. Possible interference can be expected from alkali metal atoms, for example, airborne trace impurities, that ionize in the flame. These effects are canceled by adding 2000 mg of K per hter of sample matrix. The method covers a wide range of concentrations, from trace analysis at about 20 xg L to brines at about 32 g L as summarized in Table 2. Organic samples have to be mineralized and the inorganic residue dissolved in water. The AAS method for determination of Li in biomedical applications has been reviewed . 

Manganese in aqueous solution may be analyzed by several instrumental techniques including flame and furnace AA, ICP, ICP-MS, x-ray fluorescence and neutron activation. For atomic absorption and emission spectrometric determination the measurement may be done at the wavelengths 279.5, 257.61 or 294.92 nm respectively. The metal or its insoluble compounds must be digested with nitric acid alone or in combination with another acid. Soluble salts may be dissolved in water and the aqueous solution analyzed. X-ray methods may be applied for non-destructive determination of the metal. The detection limits in these methods are higher than those obtained by the AA or ICP methods. ICP-MS is the most sensitive technique. Several colorimetric methods also are known, but such measurements require that the manganese salts be aqueous. These methods are susceptible to interference. 

Spectrometric techniques based on atomic absorption or the emission of radiation flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma-optical emission spectrometry (ICP-OES), inductively coupled plasma-mass spectrometry (ICP-MS), and cold vapor (CV)/hydride generation (HG), mainly for trace and ultratrace metal determinations. 

In all samples, Pb, Zn and Cd are determined by pulse polarography (Delcarte et al 1973) or by flame spectrometric atomic absorption. All the results, in the following tables and figures, are given in p.p.m. (mg/kg dry weight). Our sampling sites are located in a map (see Fig.3). A rural site, chosen far away from any road, serves as a control area, where samples are collected to measure the background levels of the studied heavy metals. 

Rubeska I (1988) Determination of trace elements in natural waters by atomic absorption spectrometry. In Butler LRP and Strasheim A, section editors. Atomic-, mass-, X-ray-spectrometric methods, electron paramagnetic and luminescence methods. In West TS and Niimberg HW, eds. The determination of trace metals in natural waters. Section 2, pp. 91-104. Blackwell Scientific Publications, Oxford. 

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