The determination of tetra-alkyllead and ionic alkyllead compounds in seafood

Extraction methodologies were developed for tetra-alkyllead and ionic alkyllead compounds in seafood. Tetra-alkylleads were extracted with n-hexane after the samples had been enzymatically hydrolyzed. The ionic alkylleads were complexed with diphenylthiocarbazone (dithizone) at pH 8 and 9 from enzymatically hydrolyzed samples to optimize recovery. The dithizone extracts were butylated prior to analysis by gas chromatography–atomic absorption spectrometry (GC AA). Instrumental detection limits ranged between 1.6 and 2.3 pg lead. Application to a limited number of seafood samples indicated the possible presence of trace amounts (ca 1 ng g^?1) of trimethyllead in some samples. No other alkylleads were detected.     

The determination of individual gaseous ionic alkyllead species in the atmosphere

Gaseous ionic alkyllead species (in the ng Pb m^?3 range) are collected from air by absorption in water. After extraction into n-hexane, they are propylated or butylated and quantified by gas chromatography/electrothermal atomic absorption spectrometry. Interference from inorganic lead compounds and aerosol-phase alkyllead compounds is entirely absent, whilst that from tetraalkyllead compounds is small and generally negligible. This method allows the unequivocal identification of gaseous ionic alkyllead species in the atmosphere.     

Activated carbon as adsorbent for alkyllead in air

A method is described for the determination of alkyllead in air with activated carbon as adsorbent. The main factor affecting the adsorption capacity of the activated carbon for alkyllead was the concentration of hydrocarbons in the sampled air, as these were also adsorbed. Particulate inorganic lead was collected on a membrane filter in front of the adsorbent. The alkyllead was extracted from the adsorbent into hot nitric acid, and the concentration determined by electrothermal atomic absorption spectrometry. The detection limit was 0.002 μg Pb m^?3 (sample volume 1 m³), and precision was 9.5% r.s.d. at 2.1 μg Pb m^?3 alkyllead. The method was used to monitor exposure of gasoline tank truck drivers to alkyllead. During the filling of tank trucks with leaded gasoline, alkyllead concentrations from 1 to 750 μg Pb m^?3 were found in the drivers' breathing zone, but most were well below the Norwegian TLV of 75 μg Pb m^?3.     

Hepatic butyltin concentrations in beluga whales (Delphinapterus leucas) from the St Lawrence Estuary and northern Quebec,Canada

Butyltin (tributyltin TBT; dibutyltin DBT and monobutyltin MBT) speciation was measured in the liver of beluga whales from the St Lawrence Estuary and Hudson Strait (northern Quebec). Using GC–MS, liver samples were analysed from 21 beluga whales found dead, stranded along the shores of the St Lawrence during the period 1995–1998. In all cases, including a neonate specimen, the liver was contaminated with butyltin compounds with concentrations in the range 0.04–2.1 mg Sn kg⁻¹ on a dry weight basis. Liver samples of five beluga whales from Hudson Strait obtained in the summer of 1998 were also analysed. For these animals, hepatic butyltin concentrations were consistently below the detection limit (<0.5 ng Sn g⁻¹ for MBT and <0.2 ng Sn g⁻¹ for DBT and TBT). Compared with published data on the contamination by TBT of the marine mammals of the St Lawrence in 1988, these contemporary results clearly indicate that the level of contamination of the beluga whales in this coastal marine ecosystem has not decreased ten years after regulating the use of TBT‐based antifoulants on small craft. Copyright © 2000 John Wiley & Sons, Ltd.     

Simultaneous determination of 32 antibiotics in aquaculture products using LC-MS/MS

An analytical multiclass, multi-residue method for the determination of antibiotics in aquaculture products was developed and validated. A fast, cheap, and straightforward extraction procedure followed by liquid chromatography-tandem mass spectrometry analysis was proposed. This method covers 32 antibiotics of different classes, which are frequently used in aquaculture. Three different extraction procedures were compared, and the extraction with acetonitrile (0.1 vol. % formic acid) showed the best results. The selected extraction procedure was validated at four different fortification levels (10 μg kg^?1, 25 μg kg^?1, 50 μg kg^?1, and 100 μg kg^?1). Recoveries of the tested antibiotics ranged from 70 % to 120 %, with the relative standard deviation (RSD) of triplicates lower than 20 %. The limits of quantification (LOQ) ranged from 0.062 μg kg^?1 to 4.6 μg kg^?1, allowing for the analysis of trace levels of these antibiotics in aquaculture products. The method was applied to the analysis of selected antibiotics in fish and shrimp meat available in the Czech market.     

Analysis of tributyltin in estuarine sediments and oyster tissue,Crassostrea virginica

An analytical method to determine tributyltin (TBT) in oyster tissue, Crassostrea virginica, and estuarine sediments is described. Recoveries of TBT from oysters range from 86 to 102% when samples are fortified at concentrations ranging from 22 to 890 μg kg^?1 (wet weight); recoveries from sediment range from 92 to 105% for samples fortified from 20 to 500 μg kg^?1 (dry weight). Feral oysters and natural sediments were analysed and shown to be contaminated with TBT. Oysters collected near a marina contained concentrations as high as 1.5 mg kg^?1 (wet weight).     

Butyltin compounds in severn sound,lake huron,canada

Severn Sound is a heavily used recreational and beating area in the southeast corner of Georgian Bay, Lake Huron, Canada. Because of the concern over the possible release of tributyltin species (TBT) from antifouling paints on boat hulls and marinas, surveys were carried out in 1989 and 1992 to determine the presence of this species and its degradation products dibutyltin (DBT) and monobutyltin (MBT) in this area. Many fish (pike and young–of–the–year spottail shiners) and sediment samples collected in 1989 contained detectable levels of TBT. A maximum concentration of TBT was recorded in northern pike in the spring to be 240 ng Sn g^?1. Maximum levels occurred in marinas during the beginning of the boating season and significantly reduced during the summer and early autumn, although the maximum value of TBT in sediment (392 ng Sn g^?1) was observed in the summer of 1989. The seasonal variation of TBT levels was further substantiated in the subsequent 1992 study, in which sediments from three areas in a marina were sampled at monthly intervals from May to October. TBT levels were much higher in May and then generally decreased with time. Mussels (Elliptio complanta) caged in the marina for three months also contained TBT. DBT was frequently detected in the sediments but less frequently in fish and mussels. MBT was generally below detection limits. Plants (macrophytes and cladophora) contained very small amounts of butyltin compounds.     

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.     

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.     

Simultaneous determination of thiamethoxam and its metabolite clothianidin by LC-MS/MS in goji berry and soil

In this study, an effective analytical method for simultaneous determination of thiamethoxam and its metabolite clothianidin in goji berry and soil was developed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The recoveries of the compounds in goji berry and soil at the levels of 0.005, 0.02, and 0.1 μg kg^?1 were 84.7–98.9% and the relative standard deviations (RSDs) were 0.9–3.2%. The limits of detection (LOD) for both compounds in goji berry and soil matrices were 0.001 mg kg^?1; the limits of quantification (LOQ) were 0.005 mg kg^?1 for both compounds in two matrices. The dissipation and final residual experiments in 2016 with the commercial formulation of dinotefuran ? thiamethoxam 30% suspension concentrate (SC) was conducted in goji berries in northwest China (Qinghai, Gansu, Inner Mongolia, and Ningxia). Thiamethoxam was dissipated fast in goji plant ecosystem with half-lives were 1.08–1.01 and 2.04–4.25 days in goji berry and soil. The final residues of thiamethoxam were <0.005–0.382 and <0.005–1.120 mg kg^?1 in goji berry and soil, respectively.     

Stable isotope dilution assay for the accurate determination of tricaine in fish samples by HPLC–MS–MS

Tricaine methanesulfonate is one of most commonly used anesthetics in fish during blood sampling, artificial propagation and long‐distance transportation. In this study, an accurate method for the quantitative determination of tricaine in fish samples by a stable isotope dilution assay coupled with high‐performance liquid chromatography–triple quadrupole mass spectrometry was developed. Tricaine‐D₅ was synthesized and used as an isotopically labeled internal standard for the determination of tricaine. The analytical performance of the method was validated for tricaine determination in marine fish and freshwater fish. The determination of tricaine was linear in the range of 2.0–200.0 μg L^?1. The limit of detection and limit of quantitation for fish muscle tissues were 1.0 and 4.0 μg kg^?1, respectively. Good recoveries were obtained in the range of 92.08–97.50%. The inter‐ and intra‐assay relative standard deviations (RSD values) were investigated, and the values were 0.39–3.01 and 0.85–2.77%, respectively. The values of CCα and CCβ were 10.21–10.43 and 10.42–10.87 μg kg^?1, respectively. The clearance of MS‐222 from grass carp was further studied using our method. The results demonstrate that MS‐222 could be well absorbed and rapidly eliminated after bath administration.     

Bioaccumulation of alkyllead compounds from water and from contaminated sediments by mussels

The bioconcentration of alkyllead compounds from water and from contaminated sediments by freshwater mussels (Elliptio complanata) has been investigated. Higher levels of trimethyllead than triethyllead species are accumulated for the same exposure period. In-vivo transformation of the trialkyllead species by a series of dealkylation reactions giving dialkyllead and inorganic lead(II) species appears to take place. Rates of accumulation are higher for the more contaminated sediments.     

Determination of Phenoxy Acid Pesticides in Frog and Fish Tissues by Gas Chromatography-Mass Spectrometry

A gas chromatography-mass spectrometric GC-MS method has been developed for the determination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in frog and fish tissues. After homogenization and sonication of 5 g samples, purification was achieved by a liquid phase extraction procedure using methyl-tert-butyl ether. The extract was reacted for 30 min at 80 °C with 10 % H₂SO₄ in methanol to form the corresponding methyl esters, which were simultaneously extracted with petroleum ether, and analysed by GC-MS in selected ion monitoring mode. Detection limits were 1.0 and 0.5 μg. kg^?1 for 2,4-D and 2,4,5-T respectively in tissue samples and the calibration curves showed good linearity (r ≥ 0.999). Twenty-five frog samples and forty-six fish samples from various regions in Korea were analyzed. 2,4,5-T was detected up to a maximum concentration of 16.2 μg kg^?1 in frogs and fish. The developed method may be valuable for the national monitoring project of endocrine disruptors (EDs) in biota.     

Non-dispersive atomic-fluorescence spectrometry for the determination of mercury and its application to fish samples.

A simple non-dispersive atomic-fluorescence spectrometer is described for the assay of mercury in solution at the μg l^?1 level; it has also been applied to fish samples at the mg kg^?1 level. After destruction of the fish sample, the mercury is reduced by tin(II) chloride and released from solution by a stream of argon which crosses the beam of a mercury lamp. The fluorescence signal is detected directly by a solar-blind phototube without the need for monochromators or filters. One analysis requires less than 40 min. The results correlate well with those from atomic-absorption spectrometry and neutron-activation analysis.     

Zeolite‐SiC in PVC Matrix as a New SPME Fiber for Gas Chromatographic Determination of BTEX in Water and Soil Samples

A new SPME fiber based on mixture of zeolite and silicon carbide in PVC matrix was made and its application for sampling of BTEX compounds from headspace of water and soil samples was studied. After optimization of conditions, the proposed fiber was used for determination of BTEX in real samples obtained from rivers and soils of gasoline reservoirs surroundings. The method has good linearity (0.991‐0.999) over wide concentration range. Detection limits of the method are in the range of 0.66–1.66 μg L^? and 0.01–0.12 μg kg^? for water and soil samples, respectively.     

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.     

Direct determination of bismuth and antimony in sea water by anodic stripping voltammetry

A method based on anodic stripping voltammetry at the mercury-coated graphite electrode has been developed for the direct determination of bismuth and antimony at their natural levels in sea water. Bismuth plated at -0.4 V from sea water made 1 M in hydrochloric acid gives a stripping peak proportional to concentration at -0.2 V without interference from antimony or other metals normally present. Antimony may be plated from sea water made 4 M in hydrochloric acid and gives a stripping peak at -0.2 V proportional to the sum of bismuth and antimony. By use of the standard addition technique, satisfactory results were obtained for sea water samples with concentration ranges of 0.02–0.09 μg kg^?1 for bismuth and 0.2–0.5 μg kg^?1 for antimony.     

Methylmercury in marine fish from Malaysian waters and its relationship to total mercury content

The study evaluated methylmercury concentrations, the methylmercury to total mercury ratio (%MeHg) and their correlations in ten fish species from different trophic levels. Methylmercury levels in fish studied were in the range of 0.007 to 0.914 µg g^?1 wet wt. Muscle tissue of predatory fish contained significantly (p < 0.05) higher content of methylmercury than non-predatory fish. The methylmercury to total mercury ratio ranged from 49.1% to 87.5%, with the highest ratio in predatory fish. This ratio was always higher in muscle tissue compared to the liver tissues, indicating tissue-specific binding and accumulation of methylmercury in the muscle. All the fish species showed strong positive correlation between methylmercury and total mercury levels (R ²> 0.86). Except for long tail tuna and short-bodied mackerel, all fish species showed lower methylmercury levels and estimated weekly intake as compared to the maximum values established by US FDA (of 0.5 µg g^?1) and by FAO/WHO (1.5 µg kg^?1 bodyweight), respectively. This study showed that the percentage of methylmercury is rather high in fish and fish represents the major source of this toxic mercury form to the local population.     

Wide‐scope analysis of pesticide and veterinary drug residues in meat matrices by high resolution MS: detection and identification using Exactive‐Orbitrap

A multiresidue and multiclass method for the simultaneous determination of more than 350 compounds including pesticides, biopesticides and veterinary drugs in different meat matrices (beef, pork and chicken) by ultra‐high performance liquid chromatography coupled to Orbitrap MS has been developed. In the present study, the determination of fragments was accomplished as an essential tool for a reliable identification of compounds using high resolution MS. To obtain these fragments, different strategies have been carried out in order to ensure an appropriate fragment assignment and identification. The analytical method is suitable for qualitative analysis, and it was also evaluated for quantitative analysis. Generic extraction conditions were optimized, obtaining adequate recovery and precision values for most of the studied analytes (>290). The limits of detection ranged from 2 to 16 µg kg^?1. Limits of quantification were 10 µg kg^?1 with the exception of few compounds with a higher value (50 or 100 µg kg^?1). Limits of identification were also established, and they ranged from 2 to 150 µg kg^?1. This method was applied to the analysis of 18 meat samples and some veterinary drugs as enrofloxacin and sulfadiazine were detected and further identified/quantified (with triple quadrupole) in two different samples at 33 µg kg^?1 and trace levels, respectively. No pesticides were detected in the analyzed samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous determination of sulfoxaflor in 14 daily foods using LC-MS/MS

Sulfoxa?or residues in 14 daily foods, including rice, sorghum, chilli, cucumber, white pear, apple, egg, beef brisket, chicken breast, fish, pork liver, milk, pine nut and honey, were simultaneously determined using a modified QuEChERS and LC–MS/MS method. These foods were classified into three categories to be purified. A combination of 25 mg of octadecylsilane (C18) + 25 mg of primary and secondary amine (PSA) + 50 mg of graphitised carbon black (GCB) + 150 mg of MgSO₄ was used to purify the rice, sorghum, honey, apple and white pear. A combination of 25 mg of C18 + 50 mg of PSA + 50 mg of GCB + 150 mg of MgSO₄ was used to purify the chilli and cucumber. A combination of 50 mg of C18 + 25 mg of PSA + 50 mg of GCB + 150 mg of MgSO₄ was used to purify the pine nuts, egg, beef brisket, chicken breast, fish, pork liver and milk. The linearity coefficient values were greater than 0.9975. The limit of detection and limit of quantification were in the ranges of 0.7?1.8 and 2.0?5.0 μg kg^?1, respectively. Average recoveries of the sulfoxa?or at the 14 food matrices at spiking levels of 5.0, 10 and 50 μg kg^?1 ranged from 74.0% to 100.8%, and the relative standard deviation ranged from 2.2% to 11.2%. This is a simple and rapid method for the determination of sulfoxa?or residues in various kinds of daily foods.