A new validated analytical method for the determination of tributyltin in water samples at the quantification level set by the European Union

According to recent directives of the European Union (EU), limits of quantification (LOQ) for the determination of tributyltin (TBT) in surface waters should be ca. 60 pg/L (ppq). This put very stringent requirements on analytical methodologies; definitely when they have to be applied in a routine environment. Stir bar sorptive extraction (SBSE), followed by thermal desorption (TD) and capillary gas chromatography–triple quadrupole mass spectrometry (GC–MS/MS) can provide accurate and precise data at the 2 ng/L level (ppt). For lower concentrations, matrix and reagent interferences together with contamination may provide too high TBT values. A two-dimensional heart-cut GC method was developed to fractionate TBT from interferences. The GC–GC–MS/MS method shows excellent linearity in the range 50 pg/L–4 ng/L, good repeatability (RSD < 20% at 200 pg/L), and a limit of detection of 11 pg/L. The method performance is demonstrated with representative samples i.e. harbor water and waste water samples.

► At sub-ng/L levels interferences are observed in TBT analysis.
► A new method for ultra-trace TBT analysis is presented.
► The combination of SBSE with GC–GC–MS/MS gives LOQ below 50 pg/L.
► The method can be applied in routine analysis and meets EU requirements.