AbstractThe performance of cartridges with different polar and non‐polar stationary phases (C18, C8, C2, phenyl) has been investigated for the quantitative separation of butyltin and phenyltin species (TBT, DBT, MBT, MPT, DPT, TPT), and conditions have been established to optimize the separation, using gas chromatography with a flame photometric detector, to characterize the different organotin species. Optimum separation and preconcentration of organotins is based on retention in a C18cartridge and elution with 2 cm3of 1% (v/v) HBr and 0.1% tropolone solution in methanol, being successfully applied to seawater. Finally, the possibilities of the cartridges for selective elution and their use in direct non‐chromatographic speciation are discus