Organotin stability during storage of marine waters and sediments

Summary The stability of organotin compounds in water and sediment samples during storage and pre-treatment is of paramount importance. This study presents experiments with butyltin compounds showing that the storage of filtered natural seawater in the dark at pH 2 in pyrex glass bottles is suitable to preserve the stability of tributyltin (TBT) over 4 months both at 20–25°C and 4°C. The other butyltin compounds (mono- and dibutyltin) are stable at 4°C but display some losses at 25°C. A poor recovery of butyltins in turbid water hampered the assessment of the stability on a quantitative basis: however, it could be demonstrated on a qualitative basis that the butyltin stability is uneasily achieved in water samples with high suspended matter. Finally, wet storage and freezing are found to be suitable to preserve the tributyltin stability in sediments, as well as ovendrying (at 50°C), freeze-drying and air-drying. Mono- and dibutyltin are generally subject to changes during the storage of sediments using the different methods.