Levels of polycyclic aromatic hydrocarbons,polychlorinated byphenyls,methylmercury and butyltins in the natural UNESCO reserve of the biosphere of Urdaibai (Bay of Biscay,Spain)

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), methylmercury (MeHg⁺) and butyltins (mono-, di- and tri-butyltin, MBT, DBT and TBT) were monitored in oysters (Crassostrea sp.) and sediments collected in different sampling points of the UNESCO reserve of the biosphere of Urdaibai (Bay of Biscay) from March 2006 to June 2007. In the case of oyster samples, concentrations in the 290–1814 µg kg^?1 (PAHs), 70–475 µg kg^?1 (PCBs), 75–644 µg kg^?1 (MeHg⁺) and 200–1300 µg kg^?1 (as a sum of the three butyltins) ranges were obtained. In most samples TBT was the most abundant butyltin, followed by DBT and MBT. It should be highlighted that most samples exceeded the highest range (367 µg kg^?1) found in the last mussel watch programme carried out by the National Oceanic and Atmospheric Administration (NOAA) for butyltins in oyster samples. This could be due to the presence of a shipyard in the estuary. Sediment concentrations ranged as follows: total PAHs (856–3495 µg kg^?1) and total PCBs (58–220 µg kg^?1). Organometallic species were always below the limits of detection (LODs) (0.24 µg kg^?1 for MeHg⁺, 0.6 µg kg^?1 for MBT, 0.48 µg kg^?1 for DBT and 1.1 µg kg^?1 for TBT). In both sediment and oyster PAH sources were mostly combustion. In the case of PCBs, 4-6 chlorine-atom congeners were the most abundant ones. Slight differences in the profile of PAHs as well as PCBs can be detected when the matrices were compared with each other. Finally, in the case of PAHs, sediment and water column played the main role in the accumulation pathway into the organisms in all the sampling stations.     

Elevated tri(n-butyl)tin concentrations in shellfish and sediments from Suva Harbour,Fiji

Tri(n-butyl)tin (TBT) concentrations were determined in sediments and selected shellfish from Suva Harbour, Fiji. Sediments in the immediate vicinity of foreshore slipways and boatyards were exceedingly contaminated, with a maximum observed level of 38μ g^?1 TBT-Sn. Concentrations were much lower in surficial sediments from commercial docks and yacht mooring areas, namely 16–83 ng g^?1 TBT-Sn. Mangrove oysters (Crassostrea mordax), gastropods (Thais mancinella), and bivalves (Anadara scapha) were found to have accumulated TBT. Concentrations as high as 3180 ng g^?1 TBT-Sn were found in mangrove oysters. With respect to the mangrove oyster, its widespread distribution, abundance and proclivity to accumulate TBT suggest that it is likely to be the best bioindicator species of TBT contamination in Fijian coastal waters.     

Seasonality in estuarine sources of methylated arsenic

The effect of seasonal temperature change on the release of methylated arsenic from macroalgae, phytoplankton and sediment porewaters has been investigated by a series of controlled laboratory experiments. The appearance of dissolved arsenic species in the overlying waters was monitored using a coupled hydride generation/GC AA analytical technique. The liberation of dissolved arsenic species by the macroalgae Ascophyllum nodosum was examined under estuarine conditions at 5 °C and 15 °C. At the lower temperature the release rates were 0.2 μg kg^?1 h^?1 (wet weight of material) for monomethylarsenic (MMA) and 0.5 μg kg^?1 h^?1 for dimethylarsenic (DMA), whereas at 15 °C the rates were 0.4 μg kg^?1 h^?1 and 3.2 μg kg^?1h^?1, respectively. Incubation experiments were also carried out at 15 °C using the diatom Skeletonema costatum. During the log growth phase, when chlorophyll a concentrations were in the range 1-5 μg dm^?3, the rate of appearance of DMA in the water was ～3 ng dm^?3 h^?1. Sediment samples from the freshwater and seawater end-members of the Tamar Estuary, UK, were incubated under natural conditions at 5 °C and 15 °C. The freshwater sediments released DMA in preference to MMA; the concentrations of both species increased exponentially and reached a steady state in the overlying water after 250 h. Considerably more DMA was produced at 15 °C than at 5 °C, whilst the amount of MMA produced appeared to be insensitive to the temperature increase. In contrast, the seawater sediments always produced more MMA than DMA and the increase in temperature had little effect on the production of either MMA or DMA. The results of the laboratory experiments were compared with field observations in temperate estuaries, including the Tamar Estuary. The implications of changes of water temperature on the fate of arsenic in estuaries is discussed and modifications to the estuarine arsenic cycle are proposed.     

Adsorption and desorption of tributyltin in sediments of San Diego Bay and Pearl Harbor

Adsorption and desorption of butyltin compounds from sediment under simulated estuarine conditions depends upon the characteristics of the sediment including grain size distribution, percentage of organic carbon, clay mineralogy and aqueous butyltin concentration in the overlying water column. Sediments from Pearl Harbor, Hawaii, USA, primarily consisting of calcium carbonate mud and 18–28% organic carbon by weight, have generally abundant adsorption sites and display tributyltin partition coefficients (K_p) ranging from 1000 to 5000 μg kg^?1 per μdm^?3. Adsorption and desorption of butyltin from San Diego Bay, California, USA, sediments is linearly dependent upon the characteristics of each sediment and the range in K_p values is from approximately 20 to 2500 μg kg^?1 per μg dm^?3. Sandy, low-organic carbon sediments have low K_p while fine-grained, relatively organic-rich sediments have high K_p values. Similarly, samples containing significant amounts of high cation exchange capacity (CEC) clay minerals have relatively higher adsorption potentials than those consisting of low CEC minerals.     

Determination of tributyltin oxide in coastal marine sediments and mussels by electrothermal atomic absorption spectrometry

We have devised a new method for bis(tributyltin)oxide (TBTO) determination in marine sediments and mussels. This technique involves an n-hexane/methylene chloride mixture extraction and extract purification with a sodium hydroxide wash in order to eliminate interfering compounds. TBTO is then extracted again by nitric acid and converted into an inorganic tin species; the analysis has been effected using Zeeman graphite furnace-atomic absorption spectrophotometry. The method detection limit for the matrices examined is 0.004 μg TBTO g^?1 (wet weight) and is sufficient for the analysis in real samples. The percentage recovery of TBTO from sediments and mussels samples is higher than 85% and 95% respectively. This method has been applied to TBTO level determination in sediments and mussels (Mytilus galloprovincialis) sampled in the harbour area in Taranto, where mussel culture activities are much developed; the TBTO levels obtained in sediments and mussels were in the range 15-47 ng g^?1 (wet weight) and 11-30 ng g^?1 (wet weight) respectively. Such values are comparable with those found in other harbour areas in the Mediterranean Sea.     

The determination of chlorinated long-chain paraffins in water,sediment and biological samples

Methods are described for the routine determination of traces of industrial chloro-n-paraffins having 13–30 carbon atoms and chlorine contents of 42–45% (frw/w), in environmental samples of water, sediments and biota. The procedures are based on thin-layer chromatography detection and measurement. All samples are cleaned up by liquid—solid adsorption chromatography and thin-layer chromatography but those rich in lipids require preliminary solvent extraction. The methods distinguish between chloro-n-paraffins based on long carbon chains (C₂₀–C₃₀) and those based on shorter chains (C₁₃–C₁₇). The methods cover the ranges 500 ng l^?1 to 8 μg l^?1 for water (i.e. from about the solubility limit upwards) and 50 μg kg^?1 to 16 mg kg^?1 for sediments and biota. The precision of the methods ranges from ± 50% relative at the lowest concentrations to ± 12% relative at the highest. Recoveries are about 90% for water, 80% for sediments and between 80 and 90% for biota according to sample type.     

The analyses of alkyllead compounds in fish and environmental samples in Ontario,Canada (1981–1987)

Analyses of fish and other environmental samples (clams, macrophytes, sediments and waters) from areas upstream and downstream from two alkyllead manufactures beside the St Lawrence and St Clair Rivers, Ontario, show a clear indication of elevated alkyllead levels in samples near the industries. Most species of fish contained alkyllead compounds with tetraethyllead and triethyllead as the predominant forms. Most fish from the contaminated areas contained 50–75% of total lead as alkylleads. Carp, yellow perch and white sucker were generally the most contaminated species while pike, alewife and rock bass were the least contaminated. Average alkyllead levels varied from year to year but declined steadily after 1981. For example, the geometric mean of alkyllead compounds in carp from the St Lawrence River decreased from 4207 μg kg^?1 in 1981 to 2000 μg kg^?1 in 1982 and to 49 μg kg^?1 in 1987, reflecting the reduction of alkylleads in the effluents and the closure of one of the manufactures in 1985. Alkyllead levels were consistently lower in muscle and carcass samples in comparison with whole fish containing fatty intestines. However, muscle levels were generally equal to carcass levels. The concentrations of alkyllead compounds were generally low in clams, macrophytes, sediments and waters except from the immediate vicinity of the manufactures' final effluent discharges.     

Tributyltin speciation in aquatic matrices by CGC-FPD and CGC-MS confirmation

An analytical procedure for the determination of tributyltin (TBT) in seawater, sediments and biota is described. Extraction of TBT as chloride is achieved by hydrochloric acid treatment followed by a liquid extraction using a modified solvent with a metal coordinating ligand, and a Grignard derivatization (CH₃MgCl). The organotin fraction was isolated from the derivatized extract by column chromatography. The final determination was accomplished by on-column capillary gas chromatography (CGC) coupled to a flame photometric detector (FPD) and mass spectrometry (MS) confirmation. The relative detection limits of the analytical procedure were dependent of the environmental compartment, 0.5 ng 1^–1 (as TBT) for seawater, and 0.1 ng g^–1 and 0.4 ng g^–1 for sediments and biota, respectively. The TBT recovery of fortified samples was in the range of 90% for water and biota, and of 60% in case of sediments. The reproducibility (RSD) of the whole procedure for three independent replicates was around 15%.     

Search for triorganotins along the Mar del Plata (Argentina) marine coast: finding of tributyltin in egg capsules of a snail Adelomelon brasiliana (Lamarck, 1822) population showing imposex effects

Cases of imposex were clearly identified in Adelomelon brasiliana living in the Mar del Plata (Argentina) coastal area; percentages as high as 50.0% were determined among the samples studied. These were the first reported cases of ocurrence of imposex in this type of gastropod. Since this is one of the known tributyltin (TBTs) effects, and no previous reports of determination of TBTs in gastropods eggs were found, methods were developed for the speciation and quantitative determination of organotins in A. brasiliana egg capsules. Determination of organotins in samples collected in the Mar del Plata area showed contents of tributyltin chloride (TBT) as high as 400 ng l^?1 in water and 6.50 µg g^?1 in sediments of areas of intensive boat traffic. The results showed the presence of TBT in the egg capsules of A. brasiliana at three different instars (range 0.264–1.86 µg per egg). As far as we know, this is the first report of the finding of TBT in gastropod egg capsules. Copyright © 2004 John Wiley & Sons, Ltd.     

Determination of cyflumetofen residue in water,soil, and fruits by modified quick,easy, cheap,effective, rugged,and safe method coupled to gas chromatography/tandem mass spectrometry

A new, highly sensitive, and selective method was developed for the determination of the cyflumetofen residue in water, soil, and fruits by using gas chromatography quadruple mass spectrometry. The target compound was extracted using acetonitrile and then cleaned up using dispersive solid‐phase extraction with primary and secondary amine and graphitized carbon black, and optionally by a freezing‐out cleanup step. The matrix‐matched standards gave satisfactory recoveries and relative standard deviation values in different matrices at three fortified levels (0.05, 0.5, and 1.0 mg kg^?1). The overall average recoveries for this method in water, soil, and all fruits matrix at three fortified levels ranged from 76.3 to 101.5% with relative standard deviations in the range of 1.2–11.8% (n = 5). The calculated limits of detection and quantification were typically below 0.005 and 0.015 μg kg^?1, which were much lower than the maximum residue levels established by Japanese Positive List. This study provides a theoretical basis for China to draw up maximum residue level and analytical method for cyflumetofen acaricide in different fruits.     

Life‐cycle toxicity of dibutyltin to the sheepshead minnow (Cyprinodon variegatus) and implications of the ubiquitous tributyltin impurity in test material

Dibutyltin (DBT) is used in the plastics polymerization process as a catalyst in polyvinyl chloride (PVC) products and is the primary degradation product of tributyltin (TBT), an antifoulant in marine paint. DBT and other organotin compounds make their way into the environment through antifoulants, PVC processing plants, and PVC products maintained in water and water‐handling systems. A flow‐through saltwater life‐cycle toxicity test was conducted to determine the chronic effect of DBT to the sheepshead minnow (Cyprinodon variegatus Lacepede), an estuarine species. Embryos were monitored through hatch, maturation, growth, and reproduction in DBT concentrations of 158, 286, 453, 887, and 1510 µg l^?1. Progeny were monitored for survival as embryos and fry/juveniles, and growth for 30 days post‐isolation. Mean length of parental generation fish was significantly reduced on day 30 at DBT concentrations ≥887 µg l^?1, setting the lowest observable effect concentration (LOEC) at 887 µg l^?1 and the no observable effect concentration (NOEC) at 453 µg l^?1. Fecundity, as egg viability, was significantly reduced at the LOEC. Survival of parental and progeny generation embryos and mean length, wet weight and dry weight of progeny generation juveniles were not significantly affected at concentrations ≤LOEC. TBT, a toxic impurity in DBT reversibly produced in DBT by the process of comproportionation, was also monitored throughout this study. Comparing measured levels of TBT in this study with levels exerting toxic effects in an earlier TBT life‐cycle study with C. variegatus suggests biological responses in this study were likely due to the TBT impurity and not to DBT alone. Results indicate that TBT impurity as low as 0.1% may have a significant influence on the perceived toxicity of DBT and that spontaneous production of TBT in DBT may be the major source of biological toxicity of DBT. Copyright © 2003 John Wiley & Sons, Ltd.     

Accumulation of butyltin compounds in dolphins stranded along the Mediterranean coasts

Concentrations of tributyltin (TBT) and its degradation products, monobutyltin (MBT) and dibutyltin (DBT), were determined in the liver and kidney of striped dolphins ( Stenella coeruleoalba), bottlenose dolphins ( Tursiops truncatus) and in a fetus of the common dolphin (Delphinus delphi) found stranded along the western Italian and Greek coasts in the period 1992–1994. Butyltin (BT) compounds were detected in almost all the samples analyzed and were higher in the kidney than in the liver. Total BT concentrations were 0.78–8.05 μg g⁻¹ wet wt in kidney and 0.015–1.02 μg g⁻¹ wet wt in liver of S. coeruloealba. Bottlenose dolphins had lower BT concentrations than striped dolphins. Although only one fetal sample was analyzed, it showed the highest BT concentrations of all. Unlike BT concentrations in the other adult dolphins, in the pregnant dolphin they were higher in the liver (4.35 μg g⁻¹ wet wt), suggesting that BTs are transferred from mother to fetus. No significant differences in BT concentrations were found between sexes. Of the breakdown products, DBT was predominant in most liver samples and MBT was more abundant in kidney. Although BT concentrations are known to be found in cetaceans inhabiting waters of developed countries, our observations strongly suggest that concentrations found in S. coeruleoalba were either similar to or higher than those reported for other Stenella species collected from coastal areas close to harbors or marinas. Copyright © 2000 John Wiley & Sons, Ltd.     

Dissipation dynamics of fenamidone and propamocarb hydrochloride in pepper,soil and residue analysis in vegetables by ultra-performance liquid chromatography coupled with tandem mass spectrometry

In this study, a rapid and sensitive method was developed for determining fenamidone and propamocarb hydrochloride residues in vegetables and soil by ultra-performance liquid chromatography-tandem mass spectrometry. The dissipation dynamics of fenamidone and propamocarb hydrochloride in pepper and soil was investigated in Beijing, Henan and Shandong provinces. The target compounds were extracted with methanol and cleaned with dispersive solid phase extraction using primary secondary amine. Two pairs of precursor product ion transitions for fenamidone and propamocarb hydrochloride were measured and evaluated. Average recoveries of fenamidone in potato, tomato, cabbage, pepper and soil at three levels (10, 100 and 1000 μg kg^?1) ranged from 76.91% to 107.31% with relative standard deviations (RSDs) from 2.74% to 10.87% (n = 15). The average recoveries of propamocarb hydrochloride ranged from 74.84% to 97.96% with RSDs from 2.43% to 16.16% (n = 15). The limits of detection (LODs) for fenamidone in each matrix were 0.131–0.291 μg kg^?1, and the limits of quantification (LOQs) were 0.436–0.970 μg kg^?1. The LODs for propamocarb hydrochloride were 0.125–0.633 μg kg^?1, and the LOQs were 0.417–2.11 μg kg^?1. The results also showed that the dissipation of fenamidone and propamocarb hydrochloride in pepper and soil followed first-order kinetics model more than that of bi-exponential models. The half-lives of propamocarb hydrochloride were 6.90–15.78 days in pepper and 13.56–23.02 days in soil. The half-lives of fenamidone were 7.48–11.29 days in pepper and 35.18–42.78 days in soil.     

Comparison of the acute toxicity of tributyltin and copper to veliger larvae of Nassarius reticulatus (L.)

The ban on the use of tributyltin (TBT) is promoting an increasing use of copper as an active biocide in antifouling paints, with consequent rising levels of this metal in the environment. This study assesses the acute toxicity of copper and tributyltin to the larvae of the mollusc gastropod Nassarius reticulatus. Recently hatched veligers were exposed to nominal TBT‐Sn concentrations of 0.9, 1.4, 1.9, 2.8, 3.8, 4.7 and 5.6 µg l^?1 and nominal copper concentrations of 9.4, 23.4, 46.9, 70.3, 93.8, 117.2, 140.6 and 164.1 µg l^?1 for up to 96 h, under static conditions (17 ± 1 °C and 33 ± 1 psu). The percentage of larval mortality was determined for each organometal/metal concentration and exposure time (1, 24, 48, 72 and 96 h). Both TBT and copper had a highly significant effect on larvae survival (p < 0.001) for all times of exposure, except for the first hour in the particular case of TBT. The lowest observed effect concentration for TBT‐Sn decreased over time from 3.8 µg l^?1 at 24 h to 1.9 µg l^?1 at 96 h, whereas for copper it remained constant over time (46.9 µg l^?1). The median lethal concentration (LC₅₀) for TBT‐Sn decreased from 4.87 µg l^?1 at 24 h to 1.78 µg l^?1 at 96 h, and the LC₅₀ for copper decreased from 83.08 µg l^?1 at 24 h to 58.84 µg l^?1 at 96 h. TBT is far more toxic to N. reticulatus larvae than copper. However, owing to the higher copper environmental concentrations, the risk factors of the two biocides may approach each other. This stresses the need to find adequate substitutes for organotin biocides in future antifouling paints. Copyright © 2005 John Wiley & Sons, Ltd.     

Determination of Oxolinic Acid Residues in Gilthead Seabream (Sparus aurata) Muscle Tissue and Plasma by High-Performance Liquid Chromatography

A high-performance liquid chromatographic method for the determination of oxolinic acid (OA) residues in muscle tissue and plasma of the cultured fish gilthead seabream (Sparus aurata L.), is described. OA was extracted with ethyl acetate and after centrifugation the combined extracts were evaporated. To the remaining residue 1 mL of the mobile phase was added and the extract was partitioned with n-pentane which then was rejected by aspiration. OA was chromatographed on a Zorbax^®SB-C₁₈ column at 50^oC and detected by fluorescence detection at λ_ex 327 nm and λ_em 369 nm. The mobile phase was a mixture of 0.1% trifluoroacetic acid (v/v) pH 2.0 and acetonitrile-methanol 3:2 (v/v) in a combination of 50:50 (v/v) and a flow rate of 1.0 mL min^?1, delivered isocratically. Method mean recovery (R%) achieved was 73.7 ± 4.4% (mean ± SD) for blank fortified samples (n=4) range at 50, 100 and 200 μg kg^?1 with a RSD=3.3%. The limit of detection (LOD) was 2.0 μg kg^?1 oxolinic acid in muscle tissue and plasma and the limit of quantification (LOQ) was 5.0 μg kg^?1. The method is fast and suitable to be used with safety and accuracy for the control of OA residues in cultured seabreams and a trained analyst could carry out ready for chromatography more than 50 samples per working day.     

Emission to air of volatile organotins from tributyltin‐contaminated harbour sediments

An analytical method for determining the presence in air of volatile forms (e.g. chlorides) of tributyltin (TBT) and that of methylbutyltins Me _nBu_(4?n)Sn (n = 1–3) was developed and used to establish whether dredged harbour sediments contaminated with TBT served as sources of air pollution with respect to organotin compounds. The method was based on active sampling of the air being analysed and sorption of analytes onto Poropak‐N. Sorbed methylbutyltins were extracted with dichloromethane and analysed by gas chromatography using flame photometric detection. Other butyltins were converted into butyltin hydrides prior to analysis by gas chromatography. It was shown that TBT‐contaminated sediments from Marsamxett Harbour, Malta, placed in 0.5 l chambers through which air was displaced by continuous pumping for 11 days released mainly methylbutyltins, with concentrations (as tin) reaching maximum 48 h mean values of 8.7 (Me₃BuSn), 22.1 (Me₂Bu₂Sn) and 93.0 ng m^?3(MeBu₃Sn) being measured. Other volatile forms of TBT, dibutyltin and monobutyltin were detected in the headspace air, but very infrequently and at much lower tin concentrations (<2 ng m^?3). It was also shown that methylbutyltins dissolved in sea‐water ([Sn] = 0.2 to 400 ng l^?1) were very difficult to exsolve from this medium, even on prolonged evaporation of the solutions using mechanical agitation and active ventilation. The results suggest that emission of methylbutyltins from contaminated sediments probably occurs only from the surface of the material. The environmental implications of these findings in the management of TBT‐polluted harbour sediments are discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

Determination of chemotherapeutic agents in fish and shellfish by matrix solid‐phase dispersion and liquid chromatography‐tandem mass spectrometry

Chemicals are widely used in aquaculture and one of the main recipients of these analytes is the aquatic environment. The aim of this work was to develop and validate a simple and sensitive method for the determination of multiclass chemotherapeutic agents in farmed fish and shellfish using matrix solid‐phase dispersion and liquid chromatography‐tandem mass spectrometry. Residues of azamethiphos, three avermectins, two carbamates, and two benzoylureas were extracted from samples using silica gel as clean‐up adsorbent and 0.5% acetic acid in acetonitrile as elution solvent. The extraction conditions were investigated and optimized using an experimental design. Mass spectrometry detection was carried out in positive electrospray ionization mode with multiple‐reaction monitoring scan (except for benzoylurea family). Matrix‐matched standards were used for the drugs quantification. Good linearity (R² ≥ 0.996) was observed in the range of 5–500 μg kg^?1. Limits of detection were in the range of 1.5–3.7 μg kg^?1. Recoveries from salmon samples spiked with veterinary drugs were in the range 84.9–118%. Precision was satisfactory since relative standard deviations were lower than 10.6%. The method can be successfully applied for the analysis of fish and shellfish from aquaculture.     

Determination of arsenic compounds in marine mammals with high-performance liquid chromatography and an inductively coupled plasma mass spectrometer as element-specific detector

Total arsenic concentrations and the concentrations of individual arsenic compounds were determined in liver samples of pinnipeds [nine ringed seals (Phoca hispida), one bearded seal (Erginathus barbatus)] and cetaceans [two pilot whales (Globicephalus melas), one beluga whale (Deliphinapterus leucus)]. Total arsenic concentrations ranged from 0.167 to 2.40 mg As kg⁻¹ wet mass. The arsenic compounds extracted from the liver samples with a methanol/water mixture (9:1, v/v) were identified and quantified by anion- and cation-exchange chromatography. An ICP–MS equipped with a hydraulic high-pressure nebulizer served as the arsenic-specific detector. Arsenobetaine (0.052–1.67 mg As kg⁻¹ wet mass) was the predominant arsenic compound in all the liver samples. Arsenocholine was present in all livers (0.005–0.044 mg As kg⁻¹ wet mass). The tetramethylarsonium cation was detected in all pinnipeds ( < 0.009 to 0.043 mg As kg⁻¹) but not in any of the cetaceans. The concentration of dimethylarsinic acid ranged from < 0.001 to 0.109 mg As kg⁻¹ wet mass. Most of the concentrations for methylarsonic acid ( < 0.001 to 0.025 mg As kg⁻¹ wet mass) were below the detection limit. Arsenous acid and arsenic acid concentrations were below the detection limit of the method (0.001 mg As kg⁻¹). An unknown arsenic compound was present in all liver samples at concentrations from 0.002–0.027 mg As kg⁻¹. © 1998 John Wiley & Sons, Ltd.     

Determination of fumonisins B1 and B2 in Portuguese maize and maize-based samples by HPLC with fluorescence detection

Fumonisins B₁ (FB₁) and fumonisin B₂ (FB₂) are the main members of a family of mycotoxins produced by Fusarium verticillioides, Fusarium proliferatum, and other fungi species of the section Liseola. The present work shows the results of comparative studies using two different procedures for the analysis of fumonisins in maize and maize-based samples. The studied analytical methods involve extraction with methanol/water, dilution with PBS, and clean-up through immunoaffinity columns. Two reagents (o-phthaldialdehyde and naphthalene-2,3-dicarboxaldehyde) were studied for formation of fluorescent derivatives. The separation and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method for analysis of fumonisins in maize involved extraction with methanol/water (80:20), clean-up with an immunoaffinity column, and derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). The limit of detection was 20 μg kg⁻¹ for FB₁ and 15 μg kg⁻¹ for FB₂. Recoveries of FB₁ and FB₂ ranged from 79% to 99.6% for maize fortified at 150 μg kg⁻¹ and 200 μg kg⁻¹, respectively, with within-day RSDs of 3.0 and 2.7%. The proposed method was applied to 31 samples, and the presence of fumonisins was found in 14 samples at concentrations ranging from 113 to 2,026 μg kg⁻¹. The estimated daily intake of fumonisins was 0.14 μg kg⁻¹ body weight per day.     

Occurrence of butyltin compounds in marine sediments and bivalves from three harbour areas (Saigon,Da Nang and Hai Phong) in Vietnam

A survey of organotin compounds comprising tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) in sediment and clam (Meretrix meretrix) was undertaken in Vietnam in 2003. Samples were collected from dry docks and cargo harbours in Ho Chi Minh (south), Da Nang (centre) and Hai Phong (north) cities. Measurable amounts of TBT, DBT and MBT were found in all samples. The total concentration of the butyltin compounds (ΣBTs) in sediment from shipyards and vessel repair yards (Nam Trieu, Song Cam, Lach Tray and Ba Son) were always higher than those measured in cargo ports (Hai Phong, Da Nang, and Sai Gon). The highest ΣBTs concentration (as tin: 122 ng g^?1 dry wt) was found in the sediment from Song Cam station, where seven shipyards are located. The lowest concentrations of ΣBTs occurred in sediments from the Da Nang and Hai Phong cargo ports (as tin: 21–22 ng g^?1 dry wt). This implies that the major source of BTs in the marine environment in Vietnam is from the shipbuilding activities. The ratio of TBT to Σ(MBT + DBT) in sediment was 0.67 ± 0.03 for all the sampling sites, indicating the recent use of TBT in Vietnam. For the clam (M. meretrix), the concentration of ΣBTs (as tin) varied in the range 11.2–60.1 ng g^?1 wet wt. There was a good correlation (R² = 0.85) between total organic matter‐normalized ΣBTs in sediment and hexane‐extractable organic matter‐normalized ΣBTs in clam soft tissue. The mean biota–sediment accumulation factors (organic carbon/lipid) for MBT, DBT and TBT in clam's soft tissue were found to be 1.83 ± 0.66, 1.44 ± 0.23 and 1.16 ± 0.47 respectively, indicating that sediment‐bound BTs might be an important source of contamination for the clam. Copyright © 2005 John Wiley & Sons, Ltd.