Speciation analysis of organotin compounds (OTCs) by a simultaneous hydride generation-liquid/liquid extraction and GC-MS determination

In the present work, the speciation analysis of three organotin compounds (OTCs), including tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT), by using simultaneous hydride generation-liquid/liquid extraction and GC-MS was developed. This simple method avoids the use of hazardous alkylation reagents without losing analytical performance. Multivariate design (central composite circumscribed, CCC) was applied for optimizing conditions on the hydride generation and liquid/liquid extraction. The optimized parameters were pH7.5 and NaBH₄ concentration of 0.5% m/v. Hexane was the selected solvent for liquid extraction of OTC hydrides. Quantitative recoveries of OTCs were close to 100% in seawater samples, and the achieved detection limits for TBT, DBT, and MBT were 0.5, 0.4, and 0.7 μgL^-1, respectively. Obtained analytical figures of merit were comparable or slight lower than the most used method using sodium tetraethylborate (NaBEt₄) derivatization and GC-MS. Nevertheless, the proposed method is characterized by its simplicity, low cost, and the used of highly available and safe reagents and could be considered as an alternative to the established procedure in those labs where NaBEt₄ is not available due the restriction to its transport or safety requirements.