Tin speciation

In summary, the hydride generation method cannot adequately differentiate between aquated SnIV and Sn11, which may coexist in certain, especially anaerobic, environments found in marine waters. Inorganic tin, speciated as tin (IV) , should probably be regarded as total reducible inorganic tin until more discriminatory techniques become available [578,580]. 

Andreae discusses each of these steps in detail [712]. A typical instrumental configuration to accomplish these steps is shown in Fig. 5.19 for the borohy-dride reduction/flame photometric detection system for tin speciation analysis. 

As mentioned in the introduction, methods used in tin speciation are generally composed of a succession of analytical steps (extraction, derivatisation, separation and detection) which vary drastically from one laboratory to another. The variety of methods used in the certifications is summarised in Table 9.4. 

Tin forms two stable inorganic species of Sn(II) and Sn(IV). Sn(II) is added to tin/ lead alloy plating baths. The Sn(II)/Sn(IV) ratio is important to the plating bath performance. An IC separation was carried out with the use of 0.3 mM HCl eluent [26]. Neither Sn(II) or Sn(lV) were strongly retained by the cation-exchange column used in this work. Inorganic tin speciation is quite difficult, because Sn(II) hydrolyzes easily at neutral and alkaline pH. 

Pellegrino et al. (2000) compared 12 different extraction methods for tin speciation concerning the influence of organic solvents, acidity or the presence of complexing agents They found that acidic conditions below 1 mol acidL were necessary to extract all of the investigated compounds. Tropolone improved the extraction of mono- and di-substituted organotins, while... 

Michel Astruc and his team, Les Ebdon, Wim Cofino, Freek Ariese, Roberto Morabito, Salvatore Chiavarini, Herbert Muntau for the project on tin speciation... 

Tao, H. Rajendran, R.B. Quetel, C.R. Nakazato, T. Tin speciation in the femtogram range in open ocean seawater by gas chromatography/inductively coupled plasma mass spectrometry using a shield torch at normal plasma conditions. Anal. Chem. 1999, 71,4208 215. 

Hill, S. J., Brown, A., Rivas, C., and Sparkes, S. (1995). High performance liquid chromatography—isotope dilution—inductively coupled plasma-mass spectrometry for lead and tin speciation in environmental samples. Tech. Instrum. Anal. Chem., p. 412. 

Fig. 3.3 Ion exchange chromatogram with ICP-MS detection for tin speciation. Each labeled peak corresponds to 6 ng of Sn. Strong cation exchange column. Mobile phase, 0.1 M ammonium acetate in 85% v/v methanol. Flow rate, 1 ml min . Monitoring, miz = 120. Reproduced from ref [76], J. Chromatogr. Sci., 27 (1989) 139, by permission of Preston Publications, a Division of Preston Industries, Inc.

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