A possible butyltin contamination source in wine was studied in this paper. Agglomerated cork stoppers, which were produced in Portugal, Spain, and Italy, used in wine bottles were examined. The domestic cork products, cork granules, and mucus used for cork products were also analyzed. The levels of mono-and dibutyltin compounds in corks were found in the range from <0.0024 to 3.3 and from <0.0029 to 6.7 µg of Sn/g, respectively. A low level of tributyltin contamination was also found in 2 of 31 tested samples. The presence of butyltin compounds in agglomerated cork stoppers was confirmed by GC-MS. Experimental results indicated that all overseas agglomerated cork stoppers studied contained mono-and/or dibutyltins. Butyltins were not detected in cork granules, mucus, most of the natural cork stoppers, and domestic agglomerated cork products. The concentrations of mono-and dibutyltins increased with the time in a 30-day experiment, showing that butyltin compounds can leach from agglomerated cork to the wine. When the butyltin concentrations in wine samples were compared with their levels in the corresponding agglomerated cork stoppers, a correlation was found. The potential harm of such food contamination was evaluated by the toxic research of butyltin compounds using Daphnia sp. as the experimental model.
IntroductionOrganotin compounds are widely used as heat stabilizers, catalyst agents, and biocidal compounds. Disubstituted butyltin stabilizers such as dibutyltin bis(isooctyl mercaptoacetate), or its maleate, dilaurate, along with some monosubstituted analogues can prevent the thermal degradation of PVC plastics (1). It was reported in several studies that the leaching of butyltins from PVC and related materials could lead to contamination in food products and drinking water (2-4). Tributyltin as an active ingredient in tin-based pesticides may also result in severe contamination.Forsyth et al. found the undetermined source of butyltin contamination in wine samples from different countries. Sixty-one of the 122 tested samples (50%) contained at least one of the butyltins with a concentration range from <0.1 to 160 ng/mL (5, 6). A survey on Chinese wine and liquor samples also indicated the presence of butyltin species ranged from <0.016 to 5.7 and from <0.0022 to 33.3 µg of Sn/L for mono-and dibutyltins compounds (7). Furthermore, high levels of butyltins were found in some Canadian wines which were stored and transported by PVC-lined storage tanks (8). The dominating species in wine were usually mono-and dibutyltin according to these studies. Common explanations for the sources of the butyltins in wine were the use of nonfood-grade PVC piping/containers or cultivating raw materials with butyltins-contaminated irrigation water. However, according to our experiments, a similar low level of butyltins was found in liquor samples stored in glass bottles and in those in plastic bottles (7), suggesting that the butyltins that actually leached from the plastic containers were very low. The high frequency of butyltin...