Applications, metal analysis

This method has a very general application range analysis for metals in crude oils, in their various distillation cuts, and in their residues as well as for metals contained in spent lubricating oils, water, lubricants, etc. 

However, EDTA has the widest general application in analysis because of its powerful complexing action and commercial availability. The spatial structure of its anion, which has six donor atoms, enables it to satisfy the coordination number of six frequently encountered among the metal ions and to form strainless five-membered rings on chelation. The resulting complexes have similar structures but differ from one another in the charge they carry. 

Murexide forms complexes with many metal ions only those with Cu, Ni, Co, Ca and the lanthanides are sufficiently stable to find application in analysis. Their colours in alkaline solution are orange (copper), yellow (nickel and cobalt), and red (calcium) the colours vary somewhat with the pH of the solution. 

Wetai Ion Analysis. We have reported a sensitive trace-metal analysis based upon HPLC separation of p-aminophenyl EDTA chelates and fluorescence detection by postcolumn reaction with fluorescamine (23). An application of the pyridone chemistry already discussed leads to a fluorescent-labeled EDTA (VIII). 

Braun and Richter [923] have described an application of CE in additive analysis, namely quantitative analysis of heat stabilisers in PVC, such as Irgastab 17A and 18 MOK-N, which are metal-based (in the past usually Cd, Ba and Pb, now nontoxic Ca, Zn and Sn). Quantitative metal analysis is of interest for PVC recycling purposes. Various alternative approaches are possible for such quantitative analysis, such as XRF [924], polarog-raphy [925] and AAS [923], The performance of AAS, CE and complexometric titrations in the analysis of the heavy metal content in PVC was compared [923]. For all methods investigated the metals must be separated from the polymer and transferred into an aqueous phase. 

There are bi-, tri-, and tetradentate formazan dyes7 but only the tetradentate copper complex formazan dyes have found use as commercial products. The dye Cl Reactive Blue 160, of generic structure (41), is a representative example. Because of the intensity of their colors, the metal complex formazan dyes have also found application in analysis. Thus, the dye (42) detects zinc at a concentration of 1 part in 50 million.31... 

Stripping voltammetry or stripping analysis has a special place in electrochemistry because of its extensive application in trace metal analysis. Stripping voltammetry (SV) is a two-step process as shown schematically in Fig. 18b. 12. In the first step, the metal ion is reduced to metal on a mercury electrode (thin mercury film on glassy carbon or a HMDE) as amalgam. 

One important application of analysis of variance is in the fitting of empirical models to reaction-rate data (cf. Section VI). For the model below, the analysis of variance for data on the vapor-phase isomerization of normal to isopentane over a supported metal catalyst (Cl)... 

The potential applications of NIR OFCD determination of metal ions are numerous. The detection of metal contaminants can be accomplished in real-time by using a portable fiber optical metal sensor (OFMD). Metal probe applications developed in the laboratory can be directly transferred to portable environmental applications with minimal effort. The response time of the NIR probe is comparable to its visible counterparts and is much faster than the traditional methods of metal analysis such as atomic absorption spectroscopy, polarography, and ion chromatography. With the use of OFMD results can be monitored on-site resulting in a significant reduction in labor cost and analysis time. 

Kenneth Johnson is a Senior Scientist at the Monterey Bay Aquarium Research Institute. His research interests are focused on the development of new analytical methods for chemicals in seawater and application of these tools to studies of chemical cycling throughout the ocean. His group has developed a variety of analytical methods for analyzing metals present at ultratrace concentrations in seawater. His expertise lies in trace metal analysis and instrumentation. The creation of reference materials to calibrate these instruments is important for the production of long-term, high-precision datasets. Dr. Johnson has participated on the NRC Committee on Marine Environmental Monitoring and the Marine Chemistry Study Panel. 

Flame AAS (often abbreviated FAAS) was until recently the most widely used method for trace metal analysis. However, it has now largely been superseded by inductively coupled plasma atomic emission spectrometry (see Chapter 4). It is particularly applicable where the sample is in solution or readily solubilized. It is very simple to use and, as we shall see, remarkably free from interferences. Its growth in popularity has been so rapid that on two occasions, the mid-1960s and the early 1970s, the growth in sales of atomic absorption instruments has exceeded that necessary to ensure that the whole face of the globe would be covered by atomic absorption instruments before the end of the century. 

R. J. H. Waddell, N. NicDaeid and D. Littlejohn, Classification of ecstasy tablets using trace metal analysis with the application of chemometric procedures and artificial neural networks algorithms. Analyst, 129(3), 2004, 235-240. 

Trace level analysis using ISEs was considered impossible only a decade ago. With detection limits in micromolar levels and the discrimination of interfering ions by a factor of 103-104, researchers at the time did not see any possibility of serious advances in the area and the application of ISEs in new field such as trace metal analysis in environmental samples was regarded as impossible. The potential response of an ISE in the presence of interfering ions is described by the well-known... 

The possible use of graphite-epoxy material by screen-printing technology opens the possibility of mass production of disposable sensors for heavy-metal analysis using stripping techniques. The utilization of these sensors for an extensive application in real heavy-metal samples is underway in our laboratories. 

Recently, a very important development has been made to enhance the ease of manipulation and the range of applicability of emission spectroscopy to trace metal analysis. This development is the plasma source which can be employed as an. accessory source in most direct reading emission spectrometers in place of the arc or spark or may be incorporated directly in the design of the spectrometer by the manufacturer. This development has been discussed in detail in the recent literature ( 9,53-58). 

A complexometric titration is a rapid, accurate, and inexpensive method to analyze metal ions. However, its application in metal analysis in environmental samples is very much limited, because the more common atomic absorption/emis-sion spectrometry method gives a lower detection limit. 

Beklemishev, M. K., Dmitrienko, S. G, and Isakova, N. V. (1997) Solvent extraction of metals with macrocyclic reagents and its analytical applications, Chemical Analysis (New York), 143 (Macrocyclic Compounds in Analytical Chemistry), 63-208. 

Twenty years ago the main applications of electrochemistry were trace-metal analysis (polarography and anodic stripping voltammetry) and selective-ion assay (pH, pNa, pK via potentiometry). A secondary focus was the use of voltammetry to characterize transition-metal coordination complexes (metal-ligand stoichiometry, stability constants, and oxidation-reduction thermodynamics). With the commercial development of (1) low-cost, reliable poten-tiostats (2) pure, inert glassy-carbon electrodes and (3) ultrapure, dry aptotic solvents, molecular characterization via electrochemical methodologies has become accessible to nonspecialists (analogous to carbon-13 NMR and GC/MS). 

Gel electrophoresis (GE) is a common separation technique in protein analysis and it has also been used for the speciation of metals bound to proteins [86]. In most applications, metals have been detected by autoradiography, limiting the studies to those elements for which a relatively stable radionuclide exists [87]. As an example, 75Se radiotracer allowed Se to be detected after two-dimensional GE (2-DE) separation [88]. Owing to the high sensitivity and isotopic capability of ICP-MS, this technique has been proposed as the detection tool of choice for elements in gel. The efbcient transport of the sample from the protein spot on gel to plasma has been achieved by laser ablation (LA) [89, 90] and electrothermal (ET) atomization [62, 91] techniques. The... 

With such a bright future in detection, it was worthy in this chapter to also remind researchers in the held of the early application of these complexes. The use of 1,2-enedithiolates to generate metal complexes for metal analysis predates the advent of modem spectroscopy. These colorimetric methods evolved to spectrometric methods as UV-vis spectrophotometers became commonplace in the 1960s. While the sensitivity of these classical methods is not that of modem analytical techniques, these methods are still important in metal analysis and are important to our understanding of this class of molecules. 

The analysis of aluminium alloys by atomic absorption was one of the earliest applications of the technique to non-ferrous metal analysis. Wallace... 

The adsorptive properties of colloids find some application in analysis, e.g. in the removal of phosphates by tin(IV) hydroxide oxide in the presence of nitric acid (Section V.13) and in the formation of coloured lakes from colloidal metallic hydroxides and certain soluble dyes (see Section III.23 and III.35 for aluminium and magnesium respectively). There is, however, some evidence... 

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