Analysis of Metal Complexes

Metal-EDTA complexes may be separated by anion exchange chromatography (see Fig. 3-114 in Section 3.7.4). They are detected again via electrical conductivity measurements. In electroless copper baths, for example, it is possible to distinguish between free and complex-bound EDTA. Other bath constituents do not interfere with the determination of the copper-EDTA complex, Cu(EDTA).  

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Lemr, K. et al. Analysis of metal complex azo dyes by high-performance liquid chroma-tography/electrospray ionization mass spectrometry and multistage mass spectrometry. Rapid Commun. Mass Spectrom. 2000,14,1881-1888. 

Bipyramidal orbital analysis of metal complexes indicates that most d" configurahons follow this... 

Ion-pair chromatography is also suited for the analysis of metal complexes. For their chromatographic separation, the complexes must be thermodynamically and kinetically stable. This means that complex formation must be thermodynamically possible and furthermore an irreversible process. Metal-ETDA and metal-DTPA complexes exhibit a corresponding high stability. To separate the Gd-DTPA complex (Fig. 5-21), which is of great relevance in the pharmaceutical industry, TBAOH was used as the ion-pair reagent [36], Detection was carried out by measuring the electrical conductivity in combination with a suppressor system. 

In the preceding section, the remarkable salt concentration effect on the acid dissociation equilibria of weak polyelectrolytes has been interpreted in a unified manner. In this treatment, the p/( ,pp values determined experimentally are believed to reflect directly the electrostatic and/or hydrophobic nature of polyelectrolyte solutions at a particular condition. It has been proposed that the nonideality term (Ap/Q corresponds to the activity ratio of H+ between the poly electrolyte phase and the bulk solution phase, and that the ion distribution equilibria between the two phases follow Donnan s law. In this section, the Gibbs-Donnan approach is extended to the equilibrium analysis of metal complexation of both weak acidic and weak basic polyelectrolytes, i.e., the ratio of the free metal ion activity or concentration in the vicinity of polyion molecules to that of bulk solution phase is expressed by the ApAT term. In Section III.A, a generalized analytical treatment of the equilibria based on the phase separation model is presented, which gives information on the intrinsic complexation equilibria at a molecular level. In Secs. B and C, which follow, two representative examples of the equilibrium analyses with weak acidic (PAA) and weak basic (PVIm) functionalities have been presented separately, in order to validate the present approach. The effect of polymer conformation on the apparent complexation equilibria has been described in Sec. III.D by exemplifying PMA. 

Another interesting and important example is the introduction of a complexing agent into the carrier gas during the analysis of metal complexes, which increases their stability and gives consistent results [29—31 ]. 

A number of other techniques have been applied to the analysis of metal complex luminescence. Pressure effects on luminescence of coordination complexes in single crystals (either pure or doped) can also provide information of value in evaluating excited-state distortion or metal-metal interactions of ordered solid matrices." " The magnitude of transition dipole moments and polarizability can be determined using Stark spectroscopy, and Bublitz and Boxer wrote a recent review of the technique. Two-photon excitation of transition metal complex chromophores has also been observed to yield luminescence. Recent work in this area has been reviewed by Lakowitz and co-workers. ... 

Ion-pair chromatography is also suited for the analysis of metal complexes. To be separated chromatographically, the complexes must be thermodynamically... 

Basics of the mass spectral analysis of metal complexes... 

Liquid-liquid extractions using ammonium pyrrolidine dithiocarbamate (APDC) as a metal chelating agent are commonly encountered in the analysis of metal ions in aqueous samples. The sample and APDC are mixed together, and the resulting metal-ligand complexes are extracted into methyl isobutyl ketone before analysis. 

Describe clearly the use of polarographic analysis for obtaining the values of the formation constant and stoichiometric number of metal complexes. 

Mourzina YG, Schubert J, Zander W, Legin A, Vlasov YG, Schdning MJ (2001) Development of multisensor systems based on chalcogenide thin film chemical sensors for the simultaneous multicomponent analysis of metal ions in complex solutions. Electrochim Acta 47 251-258... 

SSMS can be classified among the milliprobe techniques (Figure 8.3), i.e. it is a unique link between microprobe techniques and macroanalytical methods that are characterised by poor lateral and in-depth resolutions (as in OES), or that have no lateral resolution whatsoever (as in NAA). Also, the achievable precision and accuracy are poor, because of the irreproducible behaviour of the r.f. spark. Whereas analysis of metals, semiconductors and minerals is relatively simple and the procedures have become standardised, the analysis of nonconducting materials is more complex and generally requires addition of a conducting powder (e.g. graphite) to the sample [359]. Detection limits are affected by the dilution, and trace contamination from the added components is possible. These problems can be overcome by the use of lasers [360]. Coupled with isotope dilution, a precision of 5% can be attained for SSMS. 

There is an increasing interest in the development of electrochemical sensors and microsensors for detecting and monitoring NO or N02, due to their importance in clinical and environmental analysis. It has been suggested that transition metal electrocatalysts active for NO or N02 coordination and reduction could be exploited for the development of metal-complex film electrodes for N02 and NO sensing. However, most of the sensory devices reported so... 

In principle, the three isotope method may be widely applied to new isotope systems such as Mg, Ca, Cr, Fe, Zn, Se, and Mo. Unlike isotopic analysis of purified oxygen, however, isotopic analysis of metals that have been separated from complex matrices commonly involves measurement of several isotopic ratios to monitor potential isobars, evaluate the internal consistency of the data through comparison with mass-dependent fractionation relations (e.g., Eqn. 8 above), or use in double-spike corrections for instrumental mass bias (Chapter 4 Albarede and Beard 2004). For experimental data that reflect partial isotopic exchange, their isotopic compositions will not lie along a mass-dependent fractionation line, but will instead lie along a line at high angle to a mass-dependent relation (Fig. 10), which will limit the use of multiple isotopic ratios for isobar corrections, data quality checks, and double-spike corrections. 

For the analysis of surface-active, electroactive organic compounds, the adsorptive stripping SWV was used. The method was applied to numerous analytes. Several of them are listed in Table 3.2. Some examples of metal complexes which were used for the quantitative analysis of metal ions by adsorptive... 

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