Butyltin Determination in Sediment

The techniques described below have been tested for sediment analysis at the occasion of three interlaboratory studies (TBT-spiked sediment, harbour sediment and coastal sediment). As detailed in Section 5.3, they were first tested with simple solutions to verify that no systematic error could be attributed to the detection step. Since calibration is of paramount importance, participants were provided with pure calibrants of tributyltin chloride synthesized by TNO for the verification of their own calibrants. In all the methods, the storage of the extracts (when necessary) was always at 4 °C in the dark. The moisture correction was carried out by drying a separate sediment portion of 1 g at (105 + 2)°C for 2 h the moisture content obtained by the different laboratories ranged from 1.2 to 2.3%. 

This technique was developed in the frame of a RTD project funded by the SM T programme to serve as reference for evaluating extraction procedures [99]. 

5 g sediment were extracted by supercritical fluid extraction (CO2 and 20% methanol) after HCl addition. The extraction recovery for TBT (verified with a TBT-spiked sediment) was (82 + 6)%. Grignard derivatization was performed, using 2 mol L EtMgCl in tetrahydrofuran. Separation was by CGC (column of 30 m length, internal diameter of 0.25 mm, DB-5 as stationary phase, 0.1 pm film thickness He as carrier gas at 2 mL min injector temperature at 40 °C column temperature ranged from 40 to 290 °C). Detection was FPD (temperature of 225 °C). Calibration was carried out with butyltin chloride calibrants calibration graph and standard additions of tripropyltin as internal standard. 

5 g sediment were stirred for 1 h with 50 mL of a HBr-water mixture, followed by extraction for 2 h with tropolone/pentane and centrifugation at 1000 rpm for 10 min. The liquid phases were transferred to a 250 mL funnel in 

First method ca. 1 g sediment was extracted ultrasonically with 20 mL diethyl ether/HO in tropolone (the recovery ranged from 97 to 108% for the three butyltin compoimds as assessed by spiking the CRM with the respective compounds). Derivatization was performed by addition of 2 mol L PeMgBr in diethyl ether. The final extract was cleaned up with silica gel. Separation was by CGC (colunm of 25 m length, 0.32 mm internal diameter, methylsilicone as stationary phase, 0.8 pm film thickness He as carrier gas at 1 mL min injector temperature at 280 °C column temperature ranging from 80 to 280 °C  

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Table 5.4 Summary of the various methods used for butyltin determination in sediments [16]... 

Examples of Experimental Conditions for Derivatization Reactions Used in Butyltin Determinations in Sediment... 

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