Trace metals determination

In the search for new fluorometric reagents for trace metal determinations, ferroin-type compounds, namely 2-(2-pyridyl)-2//- and 2-(3-isoquinolyl)-3//-imidazo[4,5-/i]quinolines, and their silver, lead, and zinc chelates were tested for luminiscence in aqueous ethanol solutions at various pH values (80TAL1021). 

Otto, M. et. al. "Spectrophotometric Multicomponent Analysis Applied to Trace Metal Determinations", Anal. Chem. 1985 (57) 63-69. 

It was generally agreed that any determinations of trace metals carried out on seawater prior to about 1975 are questionable, principally due to the adverse effects of contamination during sampling, which were then little understood and lead to artificially high results. It is only in the past few years that methods of adequate sensitivity have become available for true ultra-trace metal determinations in water. 

Maximum power heating, the L vov platform, gas stop, the smallest possible temperature step between thermal pretreatment and atomisation, peak area integration, and matrix modification have been applied in order to eliminate or at least reduce interferences in graphite furnace AAS. With Zeeman effect background correction, much better correction is achieved, making method development and trace metal determinations in samples containing high salt concentrations much simpler or even possible at all. 

Bond et al. [791 ] studied strategies for trace metal determination in seawater by ASV using a computerised multi-time domain measurement method. A microcomputer-based system allowed the reliability of the determination of trace amounts of metals to be estimated. Peak height, width, and potential were measured as a function of time and concentration to construct the database. Measurements were made with a potentiostat polarographic analyser connected to the microcomputer and a hanging drop mercury electrode. The presence of surfactants, which presented a matrix problem, was detected via time domain dependent results and nonlinearity of the calibration. A decision to pretreat the samples could then be made. In the presence of surfactants, neither a direct calibration mode nor a linear standard addition method yielded precise data. Alternative ways to eliminate the interferences based either on theoretical considerations or destruction of the matrix needed to be considered. 

Holzbecker and Ryan [825] determined these elements in seawater by neutron activation analysis after coprecipitation with lead phosphate. Lead phosphate gives no intense activities on irradiation, so it is a suitable matrix for trace metal determinations by neutron activation analysis. Precipitation of lead phosphate also brings down quantitatively the insoluble phosphates of silver (I), cadmium (II), chromium (III), copper (II), manganese (II), thorium (IV), uranium (VI), and zirconium (IV). Detection limits for each of these are given, and thorium and uranium determinations are described in detail. Gamma activity from 204Pb makes a useful internal standard to correct for geometry differences between samples, which for the lowest detection limits are counted close to the detector. 

Lynch et al. [21] have described a method for the determination of organic carbon in silty lake sediments. In this method the air-dried and sifted (-250 mesh) sample is leached with 4M nitric acid-0.1M hydrochloric acid for 1.5h at 90-95°C, and the extinction of the cooled, clean solution is measured at 500nm. The extinction correlates well with weight loss (%) on heating the sample between 120 and 800°C. The precision is 26%. The same leach solution can be used for trace-metal determinations. 

Ion exchanger colorimetry has been used as a sensitive and rapid method for vanadium analysis by immobilization of 2[2-(3-5-dibromopyri-dyl)azo]-5-dimethylaminobenzoic acid onto an ion exchanger resin AG 1X2 [75]. Solid phase fluorimetry can be useful for the analysis of very dilute solutions in water analysis or trace metal determination thus a chelating 8-(benzene-sulfonamido)quinoline, immobilized on Amberlite XAD2 support, has been used for the spectrofluorimetric determination of Zn(II) and Cd(II) [76]. 

Metallic biomaterials (metals such as Ti or its alloys and others) are used for the manufacture of orthopaedic implants due to their excellent biocompatibility with respect to electrical and thermal conductivity and their mechanical properties, e.g., for hard tissue replacement such as total hip and knee joints, for fracture healing aids such as bone plates and screws or dental implants. For example, Co-Cr-Mo alloys are employed for metal-on-metal hip bearings in total joint replacements. Problems with implants occur because of ion release in patients with metal implants. To control this ion release, the ultratrace determination of Co, Cr and Mo in the blood (or serum) and urine of patients with Co-Cr-Mo alloy hip implants is carried out routinely in the author s laboratory. The trace metal determination of Co, Cr and Mo in complex matrices such as urine and blood by ICP-MS is not trivial due to the low concentrations expected in the sub-ngmF1 range, the possible danger of contamination during sample collection, sample preparation and the... 

M. Otto and W. Wegscheider, Spectrophotometric multicomponent analysis applied to trace metal determinations. Anal. Chem., 57(1), 1985, 63-69. 

Bismuth-film electrodes (BiFEs), consisting of a thin bismuth-film deposited on a suitable substrate, have been shown to offer comparable performance to MFEs in ASY heavy metals determination [17]. The remarkable stripping performance of BiFE can be due to the binary and multi-component fusing alloys formation of bismuth with metals like lead and cadmium [18]. Besides the attractive characteristics of BiFE, the low toxicity of bismuth makes it an alternative material to mercury in terms of trace-metal determination. Various substrates for bismuth-film formation are reported. Bismuth film was prepared by electrodeposition onto the micro disc by applying an in situ electroplating procedure [19]. Bismuth deposition onto gold [20], carbon paste [21], or glassy carbon [22-24] electrodes have been reported to display an... 

Bewers, 3.M. and Windom, H.C., 1982. Comparison of sampling devices for trace metal determinations in seawater. Mar. Chem., 11 71-86. 

Diemer, J. and Heumann, K.G. (1997) Bromide/bromate speciation by NTI-IDMS and ICP-MS coupled with ion exchange chromatography. Fresenius J. Anal. Chem., 357,74-79. Duan, YX., Wu, M., Jin, Q.H. and Hieftje, G.M. (1995) Vapour generation of nonmetals coupled to microwave plasma-torch mass-spectrometry. Spectrochim. Acta B, 50,355-368. Ebdon, L., Hill, S. and Jones, R (1987) Interface system for directly coupled high performance liquid chromatography-flame atomic absorption spectrometry for trace metal determination./. Anal. At. Spectrom., 2, 205-210. 

Djane, N.-K., Ndung u, K., Malcus, F., Johansson, G. and Mathiasson, L. (1997) Supported liquid membrane enrichment using an organophosphorus extractant for analytical trace metal determinations in river waters. Fresenius J. Anal. Chem., 358, 822-827. 

TABLE 5.3 Trace Metal Determination after Ozone Sample Treatment Elements Analytical ... 

Achterberg, E.P. and C.M.G. van den Berg. 1994. In-line ultraviolet-digestion of natural water samples for trace metal determination using an automated voltammetric system. Anal. Chim. Acta 291 213-232. 

In spite of its limited sensitivity, colorimetry is still useful in determination of elemental concentrations in the g range or higher (Seiler, 1988). Its main advantage is that the needed instrument, a spectrophotometer, is common in every laboratory. Colorimetric trace metal determinations are based, commonly after sample decomposition, on selective separations from interfering ions (Abbasi et al., 1988). Automated colorimetric procedures are described for the determination of N and P in trees (Stewart et al., 1990). Modern spectrophotometers provide high stability, low noise, and the advantages of computerised background control. However, for total metal determinations in environmental samples, this method is less frequently applied and has been replaced by atomic spectroscopic and electrochemical methods (Stoeppler, 1991). 

Di Bonito, M., Breward, N., Crout, N., Smith, B., and Young, S. (2008). Soil pore water extraction methods for trace metals determination in contaminated soils. In Environmental Geochemistry Site Characterization, Data Analysis, and Case Histories (B. De Vivo, H. E. Belkin, and A. Lima, eds.). Elsevier Science Publishers, Amsterdam, The Netherlands. 

Samples are often acidified with a small amount of nitric or hydrochloric acid if to be used for trace metal determinations, and stored in plastic rather than glass vials to minimize the risk of adsorption losses. Storage containers should be acid washed and thoroughly rinsed with deionized water. Acidification may result in precipitation of naturally occurring dissolved organic matter, however. Speciation studies should be completed immediately after collection on fresh samples. 

S. Munro, L. Ebdon, Application of inductively coupled mass spectrometry (ICP-MS) for trace metal determination in foods, J. Anal. Atom. Spectrom., 1 (1986), 211-221. 

Matusiewicz, H. High-pressure microwave dissolution of ceramics prior to trace metal determinations by microwave induced plasma atomic emission spectrometry. Mikrochim. Acta 111, 71-82 (1993)... 

Djane N-K, Armalis S, Ndung u K, Johansson G, and Mathiasson L. Supported liquid membrane coupled on-line to potentiometric stripping analysis at a mercury-coated reticulated vitreous carbon electrode for trace metal determinations in urine. Analyst 1998 123 393-396. 

G. Capodaglio, G. Toscano, P. Cescon, G. Scarponi, H. Muntau, Collaborative Sampling Error Assessment of Trace Metal Determination in sea water. Ann. Chim., 84 (1994), 329-.345. 

Only recently have devices been introduced which are capable of precise measurements of some trace elements their application is limited because the sensitivity of sensors is not adequate to determine trace metals at concentrations present in oceanic areas. A submersible probe for trace metal determination in the water column has been described by Tercier et al. (43) and used to determine Cd, Cu, Pb... 

Prolonged preservation of the integrity of samples with respect to metal speciation is a very difficult task and in principle it would be better to carry out the analyses on board immediately after collection and filtration. One important aspect for analytical chemists practising trace metal determination in sea water is the development of methods that can be used aboard the ship to produce large data sets. However, analytical methodologies so far available to determine trace metals in sea water are normally tedious and require a long time for the analyses, so that measurements on board, when possible, are restricted to relatively few samples... 

The main removal process for oceanic components is via sedimentation and burial thus, the interaction of dissolved metals with particles in sea water is a major indication of their concentration and distribution in the world s oceans. In open ocean areas the particle cycle is driven by the biological production of particles in the surface layers, which after processes of mineralization and packaging reach the necessary size and density to fall to the ocean bottom. On the basis of this consideration, one can say that in the open ocean area the biogeochem-ical cycle of trace metals determining their distribution and speciation is frequently dominated by biological processes. In eoastal areas or particular geographical zones, other phenomena, e.g., inorganic precipitation, can take place. 

E. Mentasti, V. Porta. O. Abolino, C. Sarzanini, Trace metal determination in antarctic sea water, Ann. Chim. (Rome). 79 (1989), 629-637. 

Simultaneous multielement determinations using plasma sources have gained in popularity. Such determinations make it possible to form correlations and to reach conclusions that were impossible with single-element determinations. For example, trace metal determinations can aid in determining the origins of petroleum products found in oil spills or in identifying sources of pollution. 

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