RESUMO
The Northern region of the Antarctic Peninsula constitutes the area with the highest human presence in West Antarctica. The human presence, with all the activities associated such as logistic, scientific and tourism operations, represents a potential risk of chemical pollution with both, organic and inorganic contaminants. Under these conditions knowledge about the presence and levels of the main persistent organic pollutants (POPs) is essential to evaluate the environmental status of this ecologically relevant and sensitive area. In this work, which complements our previous study regarding trace elements, we performed the first regional-scale monitoring of 24 PAHs (16 of them included in EPA list of primary pollutant), and organotin compounds (OTCs:TBT, DBT and MBT) in surface sediment from 68 sites comprising six different areas in Maxwell Bay, southeast coast of 25 de Mayo (King George) Island. POPs were quantified in surface sediment samples (20-30 m depth) obtained during two summer Antarctic expeditions by gas chromatography-mass spectrometry (GC-MS). The two most anthropized areas (South Fildes and Potter Cove) showed moderated evidence of pollution for PAHs and OTC. In some sampling sites the concentration of total PAHs was higher than 100 ng/g dw, while TBT was detected in only five samples, two of them located in Potter Cove (ranged between 14 and 18 ng/g dw), and three, located in South Fildes area (ranged between 118 and 416 ng/g dw). Although POPs contamination was evidenced in some samples close to scientific stations, a pollution pattern was not clearly identified.
RESUMO
A liquid chromatographic method is described for the simultaneous determination of tributyltin (TBT) and the hydroxylated intermediate 4-hydroxybutyldibutyltin (OHBuDBT). Separation was achieved in reverse phase mode on a cyanopropyl-bonded silica column under a gradient elution. Various organic solvents and additives were tested and the optimum composition of the mobile phase contained methanol, water, formic acid and tropolone as a complexing agent. Butyltin compounds were detected with an ion trap mass spectrometer interfaced to a liquid chromatograph with an atmospheric pressure chemical ionization source (LC-APCI-MS). Identification and fragmentation pattern of OHBuDBT chloride in full scan MS and MS/MS are reported for the first time using LC-APCI-MS. Gas chromatography-mass spectrometry (GC-MS) spectrum of the same compound is also reported for the first time for comparison purpose. This method allowed limits of detection (LOD) of 35 and 26 ng mL(-1) for TBT and OHBuDBT, respectively, based on successive injections of 10 microL of blank seawater extract. A liquid-liquid extraction procedure using n-hexane-ethyl acetate was developed for the simultaneous analysis of TBT and OHBuDBT chlorides in natural seawater and allowed average recoveries from 72 to 96% for the two compounds at three different spiking levels.
