Pressurised solvent extraction for organotin speciation in vegetable matrices

Occurrence of organotin compounds in food: increasing challenge of phenyltin compounds

Concentrations and distribution for 16 organotin compounds were studied in all kinds of foods, including seafood, agricultural products, and wine. Meanwhile, the degradation of the TBT or TPhT was also evaluated. Concentrations of total organotins in seafood, agricultural products, and wine were 1047.2, 469.4, and 13.5 μg Sn/kg. Meanwhile, the most frequently detected organotin in three kinds of samples were TPhT, MPhT, and MPhT, respectively. The results demonstrated that phenyltin may probably become an emerging organotin pollutant. Regarding seafood, organotin concentrations of fish and mollusks were much higher than those of crustaceans. At the same time, a significant positive correlation was observed between the concentrations of TBT and MBT (p < 0.05), and between DBT and MBT(p < 0.0001). Moreover, TPhT was significantly and positively associated with DPhT (p < 0.0001), suggesting that TPhT was the precursor of DPhT. Apart from the likely illegal use of OTs as biocides in antifouling paints for ships, anthropogenic activity like agricultural activity or industrial activity also caused organotin contamination. Further research and more effective measures should be formulated to protect the food safety. Meanwhile, monitoring of the organotin contamination should not only in Qinhuangdao, but also expand to the cities along Bohai Bay.

Simultaneous determination of three organotin pesticides in fruits and vegetables by high-performance liquid chromatography/tandem mass spectrometry

RATIONALE

The presence of organotins in the environment affects food safety, making it important to monitor the levels of organotin pesticides (OTPs) in fruit and vegetable samples.

METHODS

In the present study, a simple and low cost method for simultaneous determination of three OTPs (azocyclotin, fenbutatin oxide and triphenyltin hydroxide) in vegetable and fruit samples was developed and validated, based on solid-phase extraction and liquid chromatography/tandem mass spectrometry.

RESULTS

Extraction with acetonitrile containing 0.2% formic acid positively affected the recoveries of the three OTPs. Moreover, the simultaneous purification of the three OTPs was the most efficient using mixed-mode cation-exchange cartridges and 5.0% ammonium hydroxide in methanol as eluent, and, in this case, mild matrix effects (-9.3% to 21.6%) were obtained for the three OTPs monitored. The developed method reached limits of quantification of 1 μg kg^-1 , and linearity was satisfactory, with correlation coefficients >0.995. A fortification study showed that when spiked at 1.0-50.0 μg kg^-1 the mean trueness values were from 72.3 to 110.0% in all matrices (three vegetables and three fruits). The intra-day precision was <14.1%, and the inter-day precision (n = 11) was <18.2%.

CONCLUSIONS

The proposed method was successfully applied to the simultaneous analysis of three OTPs in vegetables and fruits.

Blood levels of organotin compounds and their relation to fish consumption in Finland

The objective of this study was to measure the concentrations of organotin compounds in the whole blood of Finnish male fishermen (n=133), their wives (n=94), and other family members (n=73), and to investigate their associations with background variables. The concentrations were generally low, less than the limit of quantification (LOQ) for the vast majority of compounds and samples. Of the organotin compounds (mono-, di-, and tributyltin, mono-, di-, and triphenyltin, and dioctyltin), only triphenyltin was detected in more than just a few samples (in 37 of 300 samples, LOQ=0.04 ng/ml). These were mainly the samples of fishermen (26/37) and their wives (10/37). For statistical analysis, concentrations of triphenyltin were divided into two categories, <LOQ and >LOQ. Of the different background variables, age and fish consumption contributed the most to the triphenyltin concentrations. When age and fish consumption (g/day) were divided into three categories, odds ratios comparing the highest with the lowest category were 3.88 for age (95% CI 1.36-11.09) and 3.48 for fish consumption (1.36-8.94), respectively. Compared with females, males had an odds ratio of 1.51 of having the concentration of triphenyltin >LOQ (0.72-3.14). To the best of our knowledge, this study confirmed for the first time with human samples that fish consumption can be associated with triphenyltin concentration in whole blood.

Determination of tributyltin (TBT) in marine sediment using pressurised liquid extraction–gas chromatography–isotope dilution mass spectrometry (PLE–GC–IDMS) with a hexane–tropolone mixture

Extraction conditions for the determination of tributyltin (TBT) in sediment samples have been developed further. The analytical procedure is based on spiking with isotopically labelled analyte, pressurised liquid extraction (PLE) with a hexane/tropolone mixture, Grignard derivatization and quantification by GC-MS. It was applied to two unknown sediment samples as part of an intercomparison exercise of the Comité Consultatif pour la Quantité de Matière (CCQM). The detection limit was approximately 1.5 ng/g TBT as Sn, while the repeatability and intermediate precision (as the coefficient of variation) were 1.9% and 3.2%, respectively. The expanded uncertainty was 6.2% (coverage factor k = 2), and the accuracy was confirmed by measurement of a certified reference material.

Optimization of an analytical method for determining organotin compounds in fish tissue by base-hydrolysis pretreatment and simultaneous ethylation–extraction procedures

To determine butyl- and phenyl-tins in fish muscle, a method including base digestion pretreatment, followed by a simultaneous ethylation-extraction procedure and gas chromatograph-flame photometric detector (GC-FPD) analysis is outlined. Key parameters that influence analyte recovery were investigated and optimized. A solution of 3% (w/v) potassium hydroxide (KOH) and 1 h digestion time at 60 degrees C were chosen in the base digestion step, to ensure complete solubilization of fish muscle and the decomposition of organotins was found to be insignificant. We found that the ratio of fish muscle/reaction solution should not exceed 0.2 g (dry weight) per 100 mL in order to avoid the matrix effect caused by the binding of hydrolyzed fish tissue with organotin ions. Ethylation of organotins were conducted at pH 6-7 with a 1% (w/v) sodium tetraethylborate (NaBEt(4)) solution for 1 h. This simple and timesaving procedure should be able to be applied to the routine analysis of organotins in other bio-tissues.

Dietary intake of organotin compounds in Finland: A market-basket study

The objective of this study was to estimate the intake of organic tin compounds from foodstuffs in a Finnish market basket. The study was conducted by collecting 13 market baskets from supermarkets and market places in the city of Kuopio, eastern Finland. Altogether 115 different food items were bought. In each basket, foodstuffs were mixed in proportion to their consumption and analysed by GC/MS for seven organic tin compounds (mono-, di-, and tributyltin, mono-, di-, and triphenyltin, and dioctyltin). Organotin compounds were detected in only four baskets, with the fish basket containing the largest number of different organotins. The European Food Safety Authority has established a tolerable daily intake of 250 ng kg(-1) body weight for the sum of dibutyltin, tributyltin, triphenyltin and dioctyltin. According to this study, the daily intake of these compounds was 2.47 ng kg(-1) body weight, of which 81% originated from the fish basket. This exposure is only 1% of the tolerable daily intake and poses negligible risk to the average consumer. However, for consumers eating large quantities of fish from contaminated areas, the intake may be much higher.