Alkyltin compounds determination

Hattori [77] extracted alkyl and alkyltin compounds from sediments with methanoic hydrochloric acid and then, following mixture with sodium chloride and water, the mixture was extracted with benzene and converted to hydrides with sodium borohydride and analysed by gas chromatography using an electron capture detector. Down to 0.02mg kg 1 organotin compounds in sediments could be determined with a recovery of 70-95%. 

Epler et al. [82] used laser enhanced ionisation as a selective detector for the liquid chromatographic determination of alkyltin compounds in sediments. The analysis was performed on a 1-butanol extract of the sediment. 

The procedures described in section 13.4.2.1 [76-78] have been applied to the determination of alkyltin compounds in marine sediments. 

Reactions of tetra-alkyltin compounds with mercury(n) iodide in 96% methanol, as with mercury(n) chloride, - are bimolecular. The variation of rate constant with alkyl group suggests an open S 2 transition state (5). Further evidence for this mechanism is provided by the variation of rate constant with solvent Y values for the particular case of the tetraethyltin compound reacting with mercury(n) chloride in a range of aqueous methanol mixtures. Solvent effects in this last series of reactions have been separated into initial state and transition state contributions by the determination of heats of solution and of transfer of the reactants. The effect of added lithium perchlorate on reaction rates for tetra-alkyltin compounds with mercury(ii) iodide again indicates bimolecular electrophilic... 

Other Approaches.— The determination of both kinetic and solubility data can, in favourable systems, permit the separation of solvent effects on reactivities into initial-state and transition-state components. Some interesting mechanistic conclusions have been drawn from such experiments on reactions of tetra-alkyltin compounds with mercury(n) halides and on Menschutkin reactions of primary amines with alkyl halides. In the former case solvent effects on both initial and transition states are important in determining reactivities, whereas in the latter case solvent effects on initial states are of predominant importance. This approach to the diagnosis of reaction mechanisms has been discussed and fully referenced in pp. 112—113 of Volume 1 and pp. Ill—112 of Volume 2 of this Report. A similar treatment of the reactions of tetra-alkyl-lead compounds with iodine, in a range of ten solvents, has recently indicated that solvent effects on both the initial and transition states are important factors in determining rates here, as for the tetra-alkyltin reactions mentioned above. ... 

ICP-MS is another means of detection that has been used for the determinations of tin compounds following HPLC separation. Two different types of plasma torch were assessed for the analysis of alkyltin species (Branch et al., 1989) An experimental low flow torch yielded better limits of detection than the standard torch. The limit of detection of TBT using the standard torch was 1.6 ng (as tin), an improvement of several orders of magnitude over an HPLC-AAS coupling. Results of analyses of spiked water samples by this method and by the HPLC-AAS method were in satisfactory agreement. 

The stabilisation effect of alkyltin thioglycolates is determined by the measurement of discoloration in a PVC formulation. The results are interpreted considering the structure of these compounds, their equilibration with alkyltin chlorides and the postulated association with chlorine atoms at the PVC primary particle surfaces. 10 refs. 

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