Phenyltin Compounds Research Articles

Antioxidative Effect of Kaempferol and Its Equimolar Mixture with Phenyltin Compounds on UV-Irradiated Liposome Membranes

The work investigates the possibility of the protective action of kaempferol on phosphatidylcholine liposome membranes exposed to the pro-oxidative action of diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT) induced by UV radiation (lambda = 253.7 nm). The concentrations of kaempferol and its equimolar mixtures with DPhT and TPhT were determined so that they induce 50% inhibition in oxidation of liposomes irradiated with UV. They are 11.6, 10.0, and 4.5 microM/L, which constitute the following sequence of antioxidative activity: kaempferol/triphenyltin > kaempferol/diphenyltin > kaempferol. This relationship is confirmed by the results on the antiradical ability of kaempferol and its mixtures with DPhT and TPhT toward the free radical 2,2-diphenyl-1-picrylhydrazyl. Similar sequences obtained in both studies suggest a possible mechanism of the antiradical action of the mixtures as free radical scavengers. Kaempferol's ability, then documented, to form complexes with phenyltins indicates (a) a possible way to liquidate the peroxidation caused by the free radical forms of phenyltins and (b) the stabilizing role of chelating in the antioxidative action of the kaempferol/phenyltins. The differentiation in the action of the compounds studied may, among others, result from different localizations in the liposome membrane, which is indicated by the results of the fluorometric studies.

Distribution of organotin compounds in tissues of mussels Mytilus edulis and clams Mya arenaria

Concentrations and composition of butyltin (BT) and phenyltin (PT) compounds were compared in tissues of mussels Mytilus edulis and clams Mya arenaria collected from the Mersey Estuary. Tributyltin (TBT) concentrations were consistently highest in digestive gland and low in muscular tissues such as siphons ( Mya) and adductor muscle ( Mytilus). Lowest concentrations were found in the periostracum surrounding the siphons of Mya. Ratios of monobutyltin (MBT), dibutyltin (DBT) and TBT to total BT content of Mytilus tissues were in the ranges 25–34%, 21–28% and 44–51%, respectively. Much higher proportions of TBT:total BT were characteristic of Mya (>80% in the digestive gland, remaining tissue and gonad) implying that slow degradation rates account for the relatively high levels of TBT in this species. TPT was the only phenyltin compound detected (albeit at relatively low levels), and, like TBT, was present in highest concentrations in the digestive gland of clams—suggesting an important dietary component in the accumulation of OTs in these bivalves.

Accumulation of butyl- and phenyltin compounds in starfish and bivalves from the coastal environment of Korea

Triphenyltin (TPT) and tributyltin (TBT) concentrations were determined in two starfish species ( Asteria pectinifera and Asterias amurensis), bivalves ( Crassostrea gigas or Mytilus edulis), and seawater samples from sites around the coasts of Korea. Both TPT and TBT concentrations in starfish ranged from 8 to 1560 ng/g and from <2 to 797 ng/g as Sn on a dry weight basis, respectively. TPT concentration accounted for 75.4% and 86.4% of total phenyltin concentration in A. pectinifera and A. amurensis, respectively, while monobutyltin, a degradation product of TBT, accounted for 86.3% and 57.2% of total butyltin, respectively. Triphenyltin concentrations in A. pectinifera were significantly correlated to water and bivalve TPT concentrations, which implies that dietary uptake of TPT from contaminated prey as well as direct uptake from surrounding water contribute to TPT body residues in the starfish. Starfish could be target organisms for monitoring TPT compound in the marine environment, due to their high accumulation and low degradation capacity towards TPT.

Concentrations of organotin compounds in sediment and clams collected from coastal areas in Vietnam

Levels of butyltin (BT) and phenyltin (PT) compounds were determined in sediments and clam Meretrix spp. collected from north and central coastal areas in Vietnam. Concentrations of TBT in sediments ranged from 0.89 to 34 ng g −1 dry wt and those in clams ranged from 1.4 to 56 ng g −1 wet wt. The levels of TBT in sediments and clams from Vietnam were within limits reported from other countries. Further, the TBT level in clams was lower than the tolerable average residue level (TARL) estimated based on tolerable daily intake (TDI). Trace amounts of PTs were also found in both sediment and clam samples. In sediments from north and central Vietnam, the concentrations of TBT were highest in the order of Hue (28 ng g −1 dry wt), Cua Luc (15 ng g −1 dry wt), Sam Son (6.3 ng g −1 dry wt), and Tra Co (5.5 ng g −1 dry wt). Among the clams from north and central Vietnam, the levels of TBT in clams from Cua Luc were dramatically high at 47 ng g −1 wet wt. TBT formed the principal butyltin species in sediment at all sites studied. The ratios of TBT in sediment were higher among BT compounds at all study sites. Of total BTs, TBT was the dominant species in clams from almost all sites studied. In spatial distribution, TPT showed a pattern similar to TBT, suggesting the use of TPT as an antifouling paint. The partition coefficient between sediment and calms was calculated. The partition coefficients of TBT and TPT were 2.01 (0.56–5.5) and 9.23 (3.1–20), respectively. These results show that sediment-bound TBT is a source of contamination to clams in addition to dissolved TBT.

Butyltin and phenyltin compounds in river i bay sediments of Tokyo

The occurrence and current status of butyltin and phenyltin compounds were investigated in sediments collected from the Arakawa and Sumida Rivers and Tokyo Bay in 2000. A series of butyltin and phenyltin compounds, including monobutyltin (MBT), dibutyltin (DBT), tributyltin (TBT), monophenyltin (MPT), diphenyltin (DPT), and triphenyltin (TPT) was detected by gas chromatography-mass spectrometry (GC-MS). The total concentrations of the butyltin (MBT + DBT + TBT) and phenyltin (MPT + DPT + TPT) compounds ranged from 25.7 to 116 and from non-detectable levels to 22.4 ng g' (as Sn), respectively. The concentrations of the organotin (OT) compounds in sediments were relatively lower than those of the samples collected in 1984. OT compounds accounted for 124% (as Sn) of total Sn in the sediments. Among the OT compounds investigated, MBT was the most prevalent in the sediments.

Determination of organotin compounds in biological samples using accelerated solvent extraction, sodium tetraethylborate ethylation, and multicapillary gas chromatography?flame photometric detection

A method has been developed for species-selective analysis of organotin compounds in solid, biological samples. The procedure is based on accelerated solvent extraction (ASE) of analytes and includes extraction of the tin species with a methanol-water (90% methanol) solution of acetic acid/sodium acetate containing tropolone (0.03% w/ v), their ethylation with NaBEt(4), and separation and detection by GC-FPD. The analytical procedure was optimized with an unspiked sample of harbor porpoise ( Phocoena phocoena) liver. Effects of ASE operational variables (extraction temperature and pressure, solvent composition, number of static extraction steps) are discussed. Method detection limits (MDL) were in the range 6-10 ng(Sn) g(-1) dry weight and 7-17 ng(Sn) g(-1) dry weight for butyl- and phenyltin compounds, respectively. Recoveries were comparable with or better than those obtained by use of other procedures reported in the literature. The analytical procedure was validated by analysis of NIES No. 11 (fish tissue) certified reference material.

Electrospray tandem mass spectrometric measurements of organotin compounds

Electrospray mass spectrometry of a series of organotin compounds in solutions of methanol are reported. Low energy collision‒induced dissociation MS/MS analysis of diagnostic precursor ions confirmed the characteristic fingerprint patterns obtained in the conventional electrospray spectra and proved to be a specific and very sensitive method for quantification of the (R3Sn)2O and the series of RnSnX4–n compounds in environmental matrices. Concentrations of butyltin compounds (TBTX, DBTX2 and MBTX3) in sediment reference materials PACS‐1 and PACS‐2 and butyltin and phenyltin compounds (TBTX, DBTX2, MBTX3, TPTX, DPTX2 and DPTX3) in Quasimeme II biota reference material (QSP001BT) were determined. The organotin compounds were extracted from the reference materials with 1‐butanol followed by dilution with methanol containing 1 mM ammonium acetate. The extracts were introduced directly into the electrospray source by a continuous flow of MeOH : H2O (60 :40). Quantitation of TBTX, DBTX2, TPTX, DPTX2 and DPTX3 was achieved by low energy CID tandem mass spectrometry using the Multiple Reaction Monitoring (MRM) analysis with the appropriate MS/MS transitions (positive ion electrospray ionization). Quantitation of MBTX3 was achieved using a negative ion electrospray CID tandem mass spectrometry method. For all samples quantitation was achieved by use of the method of standard addition, relative extraction recoveries were determined spiking with internal standards of mono‒, di‒ and triorganotin compounds separately to different samples.

The effect of cholesterol on the adsorption of phenyltin compounds onto phosphatidylcholine and sphingomyelin liposome membranes

AbstractOrganometallic compounds are widely spread in the human environment sometimes, causing a substantial health risk. Their amphiphilic character enables them to intercalate and penetrate cell membranes, potentially affecting various vital cell functions. Compound adsorption onto the membrane depends on the compound properties, as well as on the membrane composition and state. When adsorbing onto the lipidic surface, phenyltins localize at areas where lipid bilayer organization is compatible with compound spatial requirements. The lipid bilayer is a dynamic and laterally nonuniform structure with complex local and global architecture correlated with a variety of cell functions. The selective binding of a toxic compound to selected membrane areas may, therefore, interfere with some types of cellular process. We present experimental results concerning phenyltin adsorption onto the lipid bilayer surface measured with the fluorescent probe fluorescein‐PE. Model lipid bilayers were formed from lipid mixtures mimicking various plasma membrane regions. The adsorption of Ph3SnCl and P2SnCl2 onto the phosphatidylcholine–cholesterol bilayer was qualitatively different from sphingomyelin–cholesterol. The results presented indicate that phenyltins are likely to accumulate in areas containing phosphatidylcholine, outside of lipid rafts. Copyright © 2004 John Wiley &amp; Sons, Ltd.

Analytical methods for phenyltin compounds in polychlorinated biphenyl-based transformer oil samples

We present the first study on the analytical methods of phenyltin compounds (PTs) in polychlorinated biphenyl (PCB)-based transformer oil samples. Tetraphenyltin (TePhT) has been used as stabilizer for some kinds of PCBs-based transformer oil formulations. Monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TrPhT) could have been formed from TePhT during long-term use. TePhT was directly measured by gas chromatograph (GC) connected with three types of detectors, a mass spectrometer (MS), a flame photometric detector (FPD) and an atomic emission detector (AED) after dilution with hexane. MPhT, DPhT and TrPhT were propylated with Grignard reagent before measurement. The MS was the most sensitive of the detectors, with detection limits of phenyltin compounds of 30 ng/ml (MPhT), 9.8 ng/ml (DPhT), 5.5 ng/ml (TrPhT) and 0.60 ng/ml (TePhT), respectively. From the viewpoint of selectivity, MS was slightly worse than other detectors, but interference from PCBs matrices was not significant under ordinary analytical conditions. Two used transformer oil samples were analyzed using the analytical methods developed in this study. TePhT and TrPhT were found in both samples.

Contamination of organotin compounds and imposex in molluscs from Vancouver, Canada.

Gastropods and bivalves were collected at 15 sites at Vancouver and Victoria, Canada between 24 May and 7 June, 1999, to establish tissue concentrations of butyltin and phenyltin compounds, to record imposex symptoms in gastropods, and to assess the present status of organotin contamination around Vancouver. No neogastropods (such as Nucella lima) were found around Vancouver. Neogastropod populations could have been extirpated by severe TBT contamination in Vancouver, as relatively high concentrations of TBT were detected in tissues of Mytilus trossulus from Vancouver, and the neogastropods distributed in Vancouver might be sensitive to TBT. Recovery from imposex, however, was observed in neogastropod populations from three sites at Victoria and Mission Point. TBT contamination has continued around Vancouver, arising from continuous use of TBT in antifouling paints for vessels larger than 25 m in length; however, TBT has decreased around Victoria and Mission Point. Different patterns of TBT accumulation in tissue were observed among the bivalve species from Vancouver. The highest TBT concentration detected in Tresus capax suggested some possible adverse effects. TBT was the most predominant butyltin component in almost all bivalve specimens surveyed, suggesting a low rate of TBT metabolism. Phenyltin compounds were not detected in any molluscan specimens in this study.

Brief exposure to triphenyltin produces irreversible inhibition of the cytotoxic function of human natural killer cells

Phenyltin (PT) compounds (mono-, di-, and triphenyltins) are used in agricultural and consumer products. They contaminate the environment and have toxic effects on aquatic and terrestrial animals including humans. In an earlier study we demonstrated that PTs (1μM, for 1h in vitro exposure) could cause considerable inhibition of the tumor-killing function of human natural killer (NK) cells (as much as 85%). In this study we examined whether cytotoxic function can be recovered after a brief exposure (1h) to PTs. Freshly isolated lymphocytes were exposed to triphenyltin (TPT) or diphenyltin (DPT) for 1h. The compound was then removed and the cells were incubated in PT-free medium for as long as 6 days. The results indicated that exposure to 750nM TPT for 1h caused an ∼63±10% decrease in NK-cytotoxic function. However, if the cells were exposed to 750nM TPT for 1h and then allowed to incubate in TPT-free medium for 24h, there was a 91±12% loss of cytotoxic function. NK-cytotoxic function remained inhibited for as long as 6 days after removal of the TPT. A 1-h exposure to as much as 5μM DPT caused no loss of NK-cytotoxic function when the cells were tested immediately after the exposure. However, if the cells were allowed to incubate in DPT-free medium for 24h after the 1-h exposure to 5μM DPT, cytotoxicity was inhibited by 68±29% and this inhibition persisted for at least 6 days. These results indicated that short-term exposure to PTs caused persistent negative effects on human NK-cell function. The persistent effects of PTs are compared to those of the butyltins (BTs).

Metabolism of a tetraphenyltin compound in rats after a single oral dose

The metabolism of tetraphenyltin in rat liver and kidney has been examined. Tetraphenyltin and its metabolites in the tissue were determined periodically for 96 h after a single oral dose of 55.4 mg kg(-1) of tetraphenyltin by gas chromatography. The gas chromatographic method was able to determine simultaneously both inorganic tin and phenyltin compounds. Although initial (at 24 h) levels of tetraphenyltin in the liver approximated four times those in the kidneys, the levels of tetraphenyltin decreased more rapidly with time than those in the kidneys. These findings show that the tetraphenyltin accumulated more rapidly and highly in the liver, but was metabolized faster than that in the kidney. The levels of total tin in the liver 24 h after treatment were distinctly lower than those of di- or triphenyltin treatments in our previous studies and none of the animals showed characteristic symptoms. The toxic potencies of organotins generally correlate with accumulation of the chemicals. These results imply that the slight toxicities of tetraphenyltin might be due to the relatively low uptake of tin compounds after ingestion. The highest tin concentration among the metabolites of tetraphenyltin in the tissue, especially in liver, was observed as diphenyltin throughout the time period studied. These results suggest that part of the administered tetraphenyltin may cause some harmful effects as diphenyltin in rats, and this must be taken into consideration in toxicological research on tetraphenyltin.

Imposex and organotin concentrations in Buccinum undatum and Neptunea antiqua from the North Sea: relationship to shipping density and hydrographical conditions

The presence and the development of imposex were investigated in the common whelk ( Buccinum undatum) and the red whelk ( Neptunea antiqua) from the open North Sea and the Skagerrak. Imposex development was related to levels of organotins in snails and in the fine fractions (<63 μm) of the sediments they inhabit. The sampling locations were classified according to three levels of traffic densities of ships of ⩾100 gt per day passing within 15 Nautical miles of the sampling station, shipping levels being: high (>10 ships day −1), intermediate (5–10 ships day −1), and low (<5 ships day −1). Sampling stations were also classified according to presence or absence of a vertically stratified water column. In the snails the body levels of the butyltin metabolites MBT and DBT and the parent phenyltin compound TPT, were higher than those of TBT and PT metabolites. In the sediment, the parent compounds and the mono-substituted metabolites MBT and MPT were present in the highest concentrations. The highest body levels of all organotin compounds and the highest imposex indices for the common whelk were found at those locations in the Southern Bight and the German Bight that had a high shipping density as well as a homogeneously mixed water column during the whole year. At these locations sediment levels of organotins were also higher than at other sites. In contrast, the body levels of organotins were low and imposex was sometimes even completely absent in snails from stratified deep-water stations in the Skagerrak, despite a very high shipping density in the entrance area of the Baltic. In sediments from stratified locations with low or intermediate shipping densities, organotin compounds were below or close to their respective limits of detection. These stations were located in areas with a stratified water column during the whole year. The results can be explained by postulating a much higher resistance for dissolved organotins to migrate through a pycnocline. Organotins could only transgress through a pycnocline when adsorbed to settling particles that manage to transgress the boundary between layers. N. antiqua could only be obtained in sufficient numbers from deeper water stations, which almost all had a stratified water column. At stations where both snail species were obtained and imposex was present, the imposex index was higher in the red whelk. Hence N. antiqua seems to be the more sensitive species of the two. In the red whelk, imposex development increased with shipping density too, though in the smaller samples the trend was not significant. Average biota-sediment accumulation factors (BSAFs; normalised for lipid content in snails and TOC content in the fraction <63 μm in sediments) for Buccinum ranged from 0.4 to 1.0 for butyltins and were similar to literature values reported for TBT in other marine species. Higher average BSAF values were found for phenyltins 1.5 (MPT) to 17 (TPT). The high values for TPT match the ranges expected from equilibrium partitioning concepts of persistent hydrophobic compounds. The ratio of live snails to the total number of live snails plus empty shells ranged between 2.5 and 93%. This parameter might be a useful indicator to compare past and present densities of populations of both species in different areas of the North Sea.

Butyltin and phenyltin compounds in eels (Anguilla anguilla)

Tributyltin (TBT) and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), together with triphenyltin (TPT), were investigated in eels from the Thames Estuary and the Weston Canal (Merseyside). Within individual eels, the concentrations of organotin (OT) compounds varied considerably between tissues. Tributyltin concentrations were highest in heart and gall bladder and lowest in muscle and gonad. Tributyltin was generally the most predominant of butyltin (BT) compounds present in eel tissues and DBT the least. Phenyltins were detected in eels from both locations, notably the Weston Canal where TPT was present up to 0.367 μg g−1 (as Sn) in liver samples. Concentrations of OTs in liver (and muscle) were independent of weight and length in the eel populations examined. In a survey of OTs in eel populations along the Thames Estuary hepatic TBT levels ranged from 0.066–0.347 μg g−1 dry wt (as Sn) in liver of eels and were generally highest in the mid-section of the estuary, resembling the distribution pattern of TBT in sediment. Proportions of TBT to total BTs were also elevated in eel from this section of the waterway, consistent with continuing inputs in this region, albeit at relatively low levels. Major sewage treatment plants are sited here and may represent a possible source.

Organotin Pollution in Deep-Sea Fish from the Northwestern Mediterranean

Aquatic pollution resulting from extensive usage of organotin compounds has been of great concern due to their deleterious effects in nontarget organisms. However, organotin contamination in deep-sea ecosystems has been rarely studied. The presentwork attempted to determine butyltin and phenyltin compounds in deep-sea fish collected between 1000 and 1800 m depth in the NW Mediterranean. The concentration of tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), aswell astriphenyltin (TPT),and mono- anddiphenyltin (MPT, DPT) was determined in different tissues (liver, gills, digestive tube, and muscle) of several fish species. Total butyltin residues were up to 175 ng/g wet wt, and they were comparable to levels found in coastal fish collected along the Catalan coast. In contrast, deep-sea fish contained much higher levels of phenyltins (up to 1700 ng/g wet wt), and particularly TPT (up to 1430 ng/g wet wt), than previously reported concentrations in shallow-water organisms. The obtained results confirm the long-range transport of organotin compounds to the deep-sea environment, and the subsequent exposure of fish inhabiting nonpoint source areas. The use of TPT in agriculture or as an antifouling agent, its transport to the deep-sea environment associated to particulate matter, and its nonbiodegradable nature in the food chain may account for the high residue levels detected in deep-sea organisms.

Speciation of phenyltin(IV) compounds using high‐performance liquid chromatography. Part 2: The direct analysis of mixed standard solutions of triphenyltin halides/pseudohalide and of triphenyltin carboxylates containing functional group variations in the esteryl moiety

AbstractSimultaneous speciation of mixed standard solutions of triphenyltin halides (triphenyltin chloride, bromide, iodide) and pseudohalide (triphenyltin isothiocyanate) has been achieved with reversed‐phase high‐performance liquid chromatography on a Waters Spherisorb S5W ODS‐2 (octadecyl‐silica) column. An isocratic mixture of 95:5 (v/v) acetonitrile:water was used as the mobile phase at a flow rate of 1 ml min−1. A series of selected triphenyltin carboxylates, Ph3SnOCOZ, where Z = Me, Ph, CH:CHPh, CH:NOMe, CH2SC5H4N and CH2SC(S)NMe2, was also similarly analysed using this system with two separate isocratic elutions using 100% acetonitrile and 96:4 (v/v) acetonitrile:water as the mobile phase. UV detection was done at 254 nm and the total run time for each analysis was less than 3 min. The detection limits for all the phenyltin(IV) compounds were in the range 0.01–0.03 ppm. Spiked water samples containing the triphenyltin carboxylates could also be simultaneously analysed by the above method without the need for any prior derivatization, following extraction with hexane. Pretreatment of the aqueous sample with NaCl/HCl and of the organic phase with hexamethylphosphoramide enabled recoveries of about 80% of the triphenyltins. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Speciation of phenyltin(IV) compounds using high‐performance liquid chromatography: Part 1. The direct analysis of mixed standard solutions of tetraphenyltin, triphenyltin chloride, triphenyltin hydroxide and triphenyltin acetate

AbstractA rapid speciation high‐performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of phenyltin compounds. The commercially important products of triphenyltin‐chloride, ‐acetate, ‐hydroxide and tetraphenyltin were separated by reversed‐phase HPLC on a Waters Spherisorb S5W ODS‐2 (octadecylsilica) column using an isocratic mixture of 90:10 (v/v) acetonitrile:water as the mobile phase at a flow rate of 1 ml min−1. The phenyltin compounds were detected by UV detection at 254 nm and the total elution time is 8 min. The elution order is triphenyltin‐chloride, ‐acetate, ‐hydroxide and tetraphenyltin. Detection limits were 0.01 ppm for each of the triphenyltin compounds and 0.02 ppm for tetraphenyltin. Spiked water samples containing the three biocidal triphenyltin compounds could also be analysed simultaneously by the above method without the need for any prior derivatization, following extraction with toluene. The versatility of the method in sensing substituent group variations on the phenyl ring was also demonstrated by the successful resolution of the hydroxides, tris(p‐chlorophenyl)tin hydroxide, diphenyl(p‐chlorophenyl)tin hydroxide and triphenyltin hydroxide. Copyright © 2002 John Wiley &amp; Sons, Ltd.

Assessment of organotin pollution along the Polish coast (Baltic Sea) by using mussels and fish as sentinel organisms

Levels of tributyltin (TBT) and its degradation products, mono- (MBT) and dibutyltin (DBT), as well as triphenyltin (TPT), were monitored in 10 stations along the Polish coast (Baltic Sea). Mussel–– Mytilus edulis––and fish–– Platichthys flesus––were used as sentinel organisms. The bioaccumulation patterns of butyltin and phenyltin compounds varied substantially. Butyltins were detected in mussel tissue from all the sampled stations. Among them, organisms from the Gulf of Gdansk showed the highest residues (68 ng/g w.w. as Sn) in conjunction with elevated TBT/DBT ratios, which suggest recent inputs of TBT in the area. Additionally, flatfish were sampled in the Gulf of Gdansk, and different tissues (liver, digestive tube and gills) were analyzed separately. TPT, although undetected in mussels, was always present in fish. The highest organotin concentration was observed in the liver (369 ng/g w.w. as Sn) of fish caught near Gdansk port. Relatively high concentrations were observed in digestive tube, which points out the ingestion of organotin contaminated food as an important uptake route of those compounds in P. flesus.

Influence of dodecyltrimethylammonium halides on interaction of phenyltin compounds with model membranes.

The effects were studied of dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB) and dodecyltrimethylammonium iodide (DTAI) on thermotropic phase behaviour of phosphatidylcholine bilayers, as well as on 1H NMR and 31P NMR spectra, in the presence of diphenyltin dichloride (DPhT) and triphenyltin chloride (TPhT). The obtained results indicate that in the presence of the surfactant studied the interaction of phenyltin compounds with model membranes was changed and the changes depended on the kind of the counterion. The surfactants studied (especially DTAC) decrease the ability of phenyltin compounds to induce structural changes in the bilayer. It is suggested that DTAB, and especially DTAC, prevent DPhT induced interdigitated phase formation as well as formation of an inverted hexagonal phase (H(II)) in the case of TPhT/DPPC liposomes.

Sorption and desorption behavior of organotin compounds in sediment-pore water systems.

Sediments contaminated with organotin compounds (OTs), in particular triorganotins (TOTs), are abundant in areas with high shipping activities. To assess the possible remobilization of these highly toxic compounds from such sediments, a profound understanding of their sorption/desorption behavior is necessary. In this work the extent and reversibility of sorption of OTs to sediments has been investigated using contaminated freshwater harbor sediments and two certified OT containing marine sediments. Experiments conducted with perdeuterated OTs showed that sorption of OTs to sediments is a fast and reversible process involving primarily particulate organic matter (POM) constituents as sorbents. The organic carbon-normalized sediment-water distribution ratios (DOC, expressed in L/kgOC) determined in the laboratory were consistent with in-situ DOCs obtained from OT concentrations measured in sediment and pore water samples from two dated sediment cores. For both butyl- and phenyltin compounds the log DOC values were in the range of 4.7-6.1, and the following sequence was observed: DOC (tri-OT) > or = DOC (di-OT) > or = DOC (mono-OT). However, the differences were much less pronounced than would have been expected for hydrophobic partitioning of the corresponding compounds into POM. These results support our hypothesis from earlier work with dissolved humic acids that OT sorption to sediments occurs primarily by reversible formation of (innerspere) complexes between the tin atom and carboxylate and phenolate ligands present in POM. Because of the high DOC values (i.e. log DOC > or = 4) the diffusion of OTs from deeper sediments to the surface will be rather slow, and thus a major release from undisturbed sediments is not expected. However, because OTs readily desorb, any resuspension of contaminated sediments (e.g., by the tide, storms or dredging activities) will lead to enhanced OT concentrations in the overlaying water column. Furthermore, in contrastto polycyclic aromatic hydrocarbons (PAH) where large fractions may be tightly bound (in)to soot or other carbonaceous materials, OTs will be more readily bioavailable due to the fast and reversible sorption/desorption behavior.