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Abstract

Organotin compounds (OTCs) are the organometallic compounds with the most numerous applications. Today, it is more than 50 years of their intensive development and use. While they are highly useful chemicals they are also extremely toxic to a wide array of aquatic and terrestrial living organisms at very low concentrations. The quantification and identification of OTCs present in various environmental and biological samples is performed by speciation analysis.
In the present doctoral dissertation analytical methods for speciation of 12 OTCs (methyl-, butyl-, phenyl- and octyl-tins) in different aqueous environmental samples were developed.
A rapid analytical method for the simultaneous determination of 12 OTCs in salty or fresh water sample comprises of in situ derivatisation (by using NaBEt4) of OTC in salty or fresh water sample matrix adjusted to pH 6 with Tris-citrate buffer, extraction of ethylated OTCs into hexane, separation of OTCs in organic phase on 15 m GC column and subsequent quantitative determination of separated OTCs by ICP-MS. To optimise the pH of ethylation, phosphate, carbonate and Tris-citrate buffer were investigated alternatively to commonly applied sodium acetate – acetic acid buffer. The ethylation yields in Tris-citrate buffer were found to be better for TBT, MOcT and DOcT in comparison to commonly used acetate buffer. Iso-octane and hexane were examined as organic phase for extraction of ethylated OTCs. The advantage of hexane was in its ability for quantitative determination of TMeT. GC column of 15 m in length was used for separation of studied OTCs under the optimised separation conditions and its performances compared to 30 m column. The analytical method developed enables sensitive simultaneous determination of 12 different OTCs and appreciably shortened analysis time in larger series of water samples. LOD’s obtained for the developed method ranged from 0.05 – 0.06 ng Sn L-1 for methyl-, 0.11 - 0.45 ng Sn L-1 for butyl-, 0.11 – 0.16 ng Sn L-1 for phenyl-, and 0.07 – 0.10 ng Sn L-1 for octyl-tins. By applying the developed analytical method, marine water samples from the Northern Adriatic Sea containing mainly butyl- and methyl-tin species were analysed to confirm the proposed method’s applicability.
OTCs represent an important group of pollutants also in landfill leachates. For their accurate detection and quantification a new analytical procedure was developed. By using this procedure 12 OTCs were simultaneously determined. The applicability of methanol as co-extraction reagent and Tris-citrate buffer for adjustment of pH for derivatisation of OTCs in sample matrix was first carefully investigated. The use of NaBEt4 and NaBPr4 as derivatisation reagents for liquid-liquid extraction into hexane was then critically evaluated. 15 m GC column was used for rapid separation of OTCs. The developed analytical procedure was sensitive (LODs for OTCs investigated in general better than 2 ng Sn L-1) with good repeatability of measurement (RSDs mostly better than 3 %) and was successfully applied in the analysis of OTCs in landfill leachates using standard addition calibration method. Due to its simplicity and reliability it is appropriate to be used in routine laboratories for monitoring of OTCs in landfill leachates.
The newly developed analytical methods for speciation of OTCs in marine, fresh and landfill leachate samples will be used in investigations of the distribution, transformations and life cycle of OTCs in environmental ecosystems as well as serve as a tool for routine laboratory analyses.