Determination of organotin compounds in coastal sediments by propylation and GC-MS analysis

In this study, an attempt was made to determine concentrations of six species of organotins in sediment samples collected from 17 sites in the Eastern Province of Saudi Arabia. These samples were extracted using solid-liquid extraction and then derivatized by propylation using Grignard reagent. Analytes were separated and quantitatively determined on gas chromatography - mass spectrometric system. Recoveries for 0.1 μg g^-1 spiked samples were between 70 and 84%, and limits of detection of 6.6^-13 ng/g were estimated at S/N=3. Total organotin concentration found at each location was averaged at 2.31 μg g^-1. Butylated organotin species were found as tributyltin (0.441-0.695 μg g^-1), dibutyltin (0.580-0.820 μg g^-1), and monobutyltin (0.150-0.190 μg g^-1) while phenylated tins were determined as triphenyltin (0.248-0.327μg g^-1), diphenyltin (0.256-0.303μg g^-1), and monophenyltin (0.203-0.350 μg g^-1). Precision as %RSD for three determinations ranged from 11 to 14%. We used the ratios of tributyltin and triphenyltin to their respective degradation products to infer fresh input of these micro-contaminants into the marine environment.