New approach on the alkylthiol determination in water by in situ derivatization SPME followed by GC-ECD/NPD analysis
Alkylthiols are very reactive and highly volatile compounds, and thus it is difficult to determine these in the water phase. In the present work, an in situ derivatization step prior to solid-phase microextraction (SPME) has been developed for their determination in water samples. The dinitrobenzylation reaction was selected because the high chemical stability of the corresponding thioethers formed provides a significant increase in the distribution coefficient between the SPME fibre and the aqueous phase, and a potential increase in the selectivity and sensitivity. Therefore, different derivatization reaction conditions (i.e. pH, temperature, reaction time and derivatizating reagent concentration) have been studied. Then, the main parameters affecting to the SPME process, that is coating selection, extraction time profile, extraction and desorption temperatures, have been optimized. Finally, a method based on a simple 2,4-dinitrophenylation reaction at pH 8–10, in 60min at 75°C, coupled to direct SPME using PDMS-DVB fibres at 30°C for 45min is proposed. The performance of the method provided a good linearity and precision data, and the detection limits were in the low ngL −1 level.
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Document Type: Research Article
Affiliations: Environmental Chemistry Department, IIQAB-CID-CSIC, Jordi Girona,18–26, E-08034 Barcelona, Spain
Publication date: July 15, 2005