Comparison of two analytical methods for the determination of organotin compounds in marine organisms

Two analytical procedures were used for the determination of butyltin compounds in mussels.Both methods include extraction with methanol containing tropolone, derivatization, purification on Florisil and GC–MS analysis. The main difference between the procedures is in the derivatization step: one employs a Grignard reagent (n-pentylmagnesium bromide) while the other uses sodium tetraethylborate (STEB).Quantitative determinations were carried out in single ion monitoring using tripropyltin as internal standard. The accuracy of the procedures was verified on a certified reference material (ERM 477), providing good results for both methods.All the considered compounds showed lower detection limits with STEB derivatization; in particular for tributyltin (TBT), the difference between the two methods overcame one order of magnitude.An in vivo experiment was then performed, exposing mussels (Mytilus galloprovincialis) to known amount of TBT for 7 days; control and contaminated tissues were analyzed using the STEB derivatization method. Results showed the accumulation of TBT, especially in the gills.