Inorganic speciation

Evaporative LC-FTIR is rapidly gaining industrial acceptance as a useful tool in low-MW additive analysis. HPLC has also been coupled with various element-selective detectors. There is significant demand for speciation information for many elements, and the separation ability of chromatography coupled to ICP-MS offers the analyst a versatile tool for such studies. It is apparent that ICP-MS is increasingly being employed for chromatographic detection. Several modes of GC, SFC, LC and CE have been hyphenated with ICP-MS for improved detection limits compared to other traditional methods of detection such as UV-VIS spectroscopy. Inorganic speciation deserves more attention. 

R. Van Ham, L. Van Vaeck, A. Adriaens, F. Adams, B. Hodges and G. Groenewold, Inorganic speciation in static SIMS a comparative study between monatomic and polyatomic primary ions, Journal of Analytical Atomic Spectrometry, 17, 753 758 (2002). 

Stability constants of metal complexes with inorganic ligands are generally well known [30], Inorganic speciation of metals can therefore easily be evaluated by thermodynamic calculations if the composition of the solution is known [29,31],... 

Inorganic speciation, seawater concentration and biological function of the elements3. 

Quevauviller, Ph. (1995) Trends in speciation analysis - an overview of discussions on inorganic speciation. Fresenius J. Anal. Chem., 351, 345-350. 

Inorganic speciation in solution can also affect the mobility of metal ions (Doner, 1978). The formation of an ion-pair with Cl can more than double the mobility of Cd in the presence of 200molm 3NaCl. At the same chloride concentration, however, the mobilities of Cu2+ and Ni2+ are only increased slightly (5-10%), presumably because of very weak complexation with Cl. This mechanism could increase the leaching of Cd from saline soils but it may not be effective in non-saline soils because the ratio of the total concentrations of Cd Cl must be >1 106 before >50% of total Cd is complexed by Cl (estimated using the computer model TITRATOR (Cabaniss, 1987), which considered the chloro and hydroxy complexes of Cd at pH 5.0 and a total Cd concentration of 0.1 mmolm-3 equilibrium constants were taken from Lindsay (1979)). 

The inorganic speciation of trace constituents in seawater is dominated by (1) chloride complexation (2) carbonate complexation and (3) hydrolysis. Chloride complexation equilibria in the form... 

J. Szpunar, Bio-inorganic speciation analysis by hyphenated techniques, Analyst, 125 (2000), 963-988. 

Jenne, E. A., Girvin, D. C., Ball, J. W., and Burchard, J. M. Inorganic speciation of silver in natural waters - fresh to marine. Chapter 4, p. 41-61, Klein, D. A., ed., "Environmental Impacts of Nucleating Agents Used in Weather Modification Programs," 256 p. Dowder, Hutchinson and Ross, Stroudsberg, Pa. 1978. 

The inorganic speciation presented in Table 1 is primarily taken from the compilations of... 

Turner et al. (1981) and Byrne et al. (1988). Turner et al. (1981) used a database of stability constants for more than 500 metal complexes to calculate the inorganic speciation for 58 trace elements in model seawater at pH 8.2, 25 °C, and 1 atm. Byrne et al. (1988) extended this work by considering the influence of temperature and pH on speciation. The free hydrated divalent cation dominates the dissolved inorganic speciation of Zn(II) and the first transition series metals Mn(II), Co(II), and Ni(II). Strongly hydrolyzed trace metals include Be(II), Al(III), Fe(III),... 

Dietz and Perez used ion-exchange chromatography to achieve separations of monomethylarsonate, dimethylarsenite and tri- and pentavalent arsenic. Here, further inorganic speciation relies on redox-based colorimetry . Both the accuracy and precision suffer from the low As(III)/As(IV) and As(total)/P ratios normally encountered in the environment. 

Following the work of Garrels and Thompson (1962), many chemists have made calculations of the inorganic speciation of fresh and marine waters among these are Stumm and Brauner (1975), Turner et al. (1981), and, more recently, Byrne et al. (1988). The latter workers paid particular attention to the influence of temperature and pH and provided a useful compilation of relevant thermodynamic data (including enthalpies, from which temperature dependences can be estimated). Palmer and van Eldik (1983) have presented a detailed review of metal complexes with carbonic species. 

Uptake of Iron Fe is perhaps the most important of all the bioactive trace elements. However, its marine chemistry and inorganic speciation are rather... 

Since the inorganic and organic chemistry of Cu(II) has been the object of considerable scrutiny, it is useful to consider in some detail the application of equation 9 to the chemistry of Cu(II) in organic rich systems. Recent work on inorganic Cu(II) speciation is sufficient to provide a reasonable assessment of the terms and assessment of the inorganic speciation terms in... 

For zinc and the first transition series metals manganese, iron, cobalt, and nickel, the free hydrated divalent cation form dominates the dissolved inorganic speciation. The trivalent metal cations Al +, Ga +, Tl +, Fe " ", and Bi + are strongly hydrolyzed (i.e., they form strong complexes with... 

Other important inorganic species are the chloride and carbonate complexes. Chloride complexes are important in the inorganic speciation of Ag" ", Cd, and Hg. Unlike the strongly hydrolyzed metals, chloride dominated metals are only moderately affected by temperature and pH. Of this group, Hg " " is complexed by chloride to the greatest extent. The side reaction coefficient of Hg with respect to chloride is at 5°C. Carbonate complexes... 

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