Redistribution reactions of butyl- and phenyltin species during storage in methanol
Dong Nguyen Van, Richard Lindberg and Wolfgang Frech
Abstract: The stability of organotin species, which are frequently used as standards, in methanol has been investigated by gas chromatography coupled to either quartz furnace atomic absorption spectrometry, inductively coupled plasma mass spectrometry or mass spectrometry. Ethylation with sodium tetraethylborate was used during sample preparation. The species composition of single or mixed standard solutions at a concentration of 10 µg g–1 was investigated after storing at –20 °C, +4 °C and +22 °C for various time periods. All butyltin species (monobutyltin—MBT, dibutyltin—DBT and tributyltin—TBT) were found to be stable for all storage conditions, even when mixed. The single triphenyltin (TPhT) standard was also stable, whereas mono-and diphenyltin (MPhT; DPhT) were unstable. MPhT redistributed to DPhT and inorganic tin (IOT), while DPhT redistributed to MPhT and to a minor extent to TPhT. In a mixture containing MBT, DBT, TBT, MPhT, DPhT and TPhT, besides the above mentioned reactions, DPhT was found to react strongly with MBT forming up to 73% monobutyl-monophenyltin (MBMPhT) and MPhT. The composition of MBMPhT was investigated by GC-MS. Suggestions for the type of reactions leading to the redistribution of OT species are outlined and suggestions on how to prepare stable OT standards are made.