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1.
J Chromatogr A ; 1608: 460409, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31399210

RESUMO

In this study two different analytical approaches have been developed to determine the presence of several cyanotoxins in saline water samples from a continental salt marsh. A salting-out assisted liquid-liquid extraction (SALLE) has been used in combination with ultra-high performance liquid chromatography-tandem mass spectrometry and UV-diode array detection (UHPLC-MS/MS and UHPLC-DAD). The target analytes are eight microcystins named MC-RR, MC-YR, MC-LR, MC-WR, MC-LA, MC-LY, MC-LW, MC-LF and nodularin (NOD), covering a wide range of polarities. The separation was achieved using a Zorbax Eclipse Plus RRHD C18 column (50 × 2.1 mm, 1.8 µm) in less than 7.5 and 5.5 min for UV and MS/MS detection, respectively. The mobile phase used consisted of water (solvent A) and acetonitrile (MeCN) (solvent B), both containing 0.01% of formic acid for DAD and 0.4% of formic acid for MS/MS detection, at a flow rate of 0.4 mL min-1. The temperature of the column was set at 25 °C and 20 µL of sample were injected. The main parameters affecting the SALLE procedure were studied and the following optimum values were obtained: neutral pH, 2 mL of acetonitrile as extraction solvent and 1.2 g of ammonium sulfate as salting-out agent for 4 mL of water sample. The validation protocols for both methods were accomplished with real water samples obtaining LODs ranging from 1.0 to 3.4 µg L-1 and 0.02 to 0.11 µg L-1 for DAD and MS/MS respectively. Although the SALLE-UHPLC-DAD methodology is easier and cheaper than UHPLC-MS/MS significantly better detection limits were achieved with tandem mass spectrometry as well as allowing for unambiguous identification. Extraction recoveries were higher than 77.0% (except for MC-RR and NOD which were 53.2% and 54.3, respectively) with satisfactory inter-day and intra-day precisions (RSD below 13.3%).


Assuntos
Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental/métodos , Extração Líquido-Líquido , Toxinas Marinhas , Microalgas/química , Água do Mar/química , Espectrometria de Massas em Tandem , Limite de Detecção , Toxinas Marinhas/análise , Toxinas Marinhas/isolamento & purificação , Microcistinas/análise , Microcistinas/isolamento & purificação , Reprodutibilidade dos Testes , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/isolamento & purificação
2.
Ecotoxicol Environ Saf ; 183: 109477, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31369939

RESUMO

The increasing eutrophication of freshwater and brackish habitats globally has led to a corresponding increase in the occurrence of harmful cyanobacterial blooms. Cyanobacteria can produce highly toxic substances such as microcystins (MCs) that affect the health of livestock, wildlife, and humans. The present study broaden the understanding of cyanobacteria ecology and MC dynamics in the field, focusing on the estimation of the production and sedimentation rates of MCs in a natural habitat. The nutrient concentrations of the reservoir water and sediment pore water were monitored at 3-h intervals for 24 h during the summer cyanobacterial bloom. The DIN uptake rate of Microcystis in the Isahaya reservoir was estimated and the large-scale blooms in the reservoir were largely controlled by the interactions between rainfall and nutrient levels in the warm season. By using calculations based on the nitrogen budgets and tracking changes of the MC concentrations in the water column, the total MC production and sedimentation rates were estimated to be 52.2 kg MCs d-1 and 21.5 kg MCs d-1, respectively. Although MCs could be degraded in the environment, the MC sedimentation still comprised 41% of the in-water production.


Assuntos
Toxinas Bacterianas/análise , Baías/microbiologia , Toxinas Marinhas/análise , Microcistinas/análise , Toxinas Bacterianas/metabolismo , Baías/química , Ecossistema , Eutrofização , Sedimentos Geológicos/química , Japão , Toxinas Marinhas/metabolismo , Microcistinas/metabolismo , Microcystis/metabolismo , Nitrogênio/metabolismo , Nutrientes , Estações do Ano
3.
Environ Monit Assess ; 191(9): 569, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31418103

RESUMO

Microcystins (MCs) are toxic secondary metabolites produced by several cyanobacteria genera that have been implicated in human cancer cases and deaths. Human exposure routes include direct contact with contaminated water and the consumption of contaminated food. The present study investigated the presence of MCs in three commonly consumed vegetables at the point of sale in market places as a means of assessing the direct human health risk of buying vegetables. Overall, 53% of the vegetables obtained from different markets had levels of MCs that were higher than 1.00 µg/g. Amaranthus hybridus L. (smooth amaranth) had the highest MC concentration (4.79 µg/g) in samples obtained from Sabon Gari Market, while Lactuca sativa L. (garden lettuce) had the lowest concentration (0.17 µg/g) in samples obtained from Dan-Magaji Market. The highest total daily intake (TDI) of MCs by an adult weighing 60 kg was 3.19 µg/kg for A. hybridus, 1.41 µg/kg for Brassica oleracea L. (cabbage), and 2.94 µg/kg for L. sativa. The highest TDI of MCs for a child weighing 25 kg was highest in A. hybridus (1.91 µg/kg), followed by L. sativa (1.77 µg/kg). These results revealed that the consumption of vegetables sold in markets in Zaria, Nigeria, during the dry season represents a major exposure route to MCs. There is, therefore, an urgent need to develop policies and monitoring strategies to tackle this problem in developing countries.


Assuntos
Amaranthus/química , Brassica/química , Contaminação de Alimentos/análise , Alface/química , Microcistinas/análise , Humanos , Nigéria
4.
Biosens Bioelectron ; 142: 111550, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31387024

RESUMO

Microcystins are the most worldwide extended and common toxins produced by cyanobacteria in freshwater. Microcystin-leucine arginine (MC-LR), associated with the most toxic incidents involving microcystins, are within the cyanobacteria (intracellular) until released into the surrounding waters (extracellular) during cell lysis. Therefore, the relationship between intracellular and extracellular cyanotoxins will allow a comprehensive risk of cyanobacteria-containing waters, preventing disease and improving human safety. In this work, we present the development of a novel portable microfluidic sensing platform for the simultaneous detection of free (extracellular) and total MC-LR (intracellular and extracellular). The integrated system contains the sample processing and detection modules capable of performing the chemical lysis, filtration, sample mixing with antibodies, and electrochemical detection of MC-LR based on an indirect strategy. The performance of the immunosensors was evaluated by electrochemical impedance spectroscopy, showing a linear dynamic range between 3.3 × 10-4 and 10-7 g L-1 and a limit of detection of 5.7 × 10-10 g L-1. The results demonstrate the potential of the developed portable biosensor platform and its suitable application for the analysis of MC-LR at regulated levels for drinking water. Finally, the integrated system was able to simultaneously detect the free and total MC-LR on a Microcystis aeruginosa culture. To the best of our knowledge this is the first described system that can differentiate between intracellular and extracellular concentration of MC-LR. This novel electrochemical sensing platform avoids the multiple processing steps typically needed for standard MC-LR analysis in the laboratory and provides an early warning system for MC-LR remote monitoring in water.


Assuntos
Técnicas Biossensoriais/instrumentação , Espectroscopia Dielétrica/instrumentação , Água Doce/análise , Microcistinas/análise , Desenho de Equipamento , Limite de Detecção , Microcystis/química , Poluentes Químicos da Água/análise
5.
Environ Pollut ; 253: 790-799, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31344540

RESUMO

Microcystin-LR (MCLR) is the most commonly encountered toxic microcystin variant. MCLR is usually present along with common surface water constituents such as inorganic ions and natural organic matter (NOM) which compete with MCLR for active sites during ion exchange (IX) process. Consequently, development of a multicomponent competitive model is essential for practical IX applications. This is critically important given that the NOM characteristics (charge density and molecular weight distribution) and inorganic ions concentrations are spatially variable and can change seasonally. In the present study, a systematic study was carried out into the multicomponent interactions of IX resin with inorganic ions and NOM during the MCLR removal process. This involved evaluation of MCLR removal in a single component system (i.e., MCLR only), a dual component system (MCLR and one other contaminant such as NOM), and a multiple component system (MCLR with NOM and different inorganic ions present in natural waters). A comprehensive understanding of the dynamic adsorption behavior showed that the experimental data for single component systems agree well with a Freundlich isotherm. For multicomponent interactions, the Equivalent Background Concentration (EBC) model which is derived from the Ideal Adsorption Solution Theory (IAST) provided the best correlation with the experimental data in natural waters. The concentrations of competing NOM and inorganic ions estimated by the EBC model were <10% of their initial concentrations. Sulphates are the most competitive inorganic ions followed by nitrates and bicarbonates and the multicomponent interactions could be well predicted by using the IAST-EBC model. However, the EBC model failed in the presence of higher molecular weight Suwannee River Humic Acid (SRHA) molecules due to neglecting of the pore blocking phenomenon. In the presence of higher molecular weight SRHA molecules, the Redlich-Peterson Isotherm (RP) model exhibited a better performance than the Sheindorf-Rebuhn-Sheintuch (SRS) and the EBC models.


Assuntos
Troca Iônica , Microcistinas/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Substâncias Húmicas/análise , Microcistinas/análise , Peso Molecular , Nitratos , Sulfatos , Poluentes Químicos da Água/análise
6.
Chem Biol Interact ; 311: 108761, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31348918

RESUMO

Water contamination by cyanobacterial blooms is a worldwide health hazard to humans as well as livestock. Exposure to Microcystins (MCs), toxins produced by various cyanobacterial or blue green algae found in poorly treated drinking water or contaminated seafood such as fish or prawns are associated with hepatotoxicity, nephropathy and neurotoxicity and in extreme cases, death in humans. MC congeners, currently >240 known, differ dramatically in their uptake kinetics, i.e. their uptake via OATP1B1 and OATP1B3, in OATP overexpressing human HEK293 cells and primary human hepatocytes. It is thus likely that MC congeners will also differ with respect to the cellular efflux of the parent and conjugated congeners, e.g. via MRPs, MDRs, BCRP or BSEP. Consequently, the role and kinetics of different human efflux transporters - MRP, MDR, BCRP and BSEP in MC efflux was studied using insect membrane vesicles overexpressing the human transporters of interest. Of the efflux transporters investigated, MRP2 displayed MC transport. Michaelis-Menten kinetics displayed mild co-operativity and thus allosteric behavior of MRP2. MC transport by MRP2 was MC congener-specific, whereby MC-LF was transported more rapidly than MC-LR and -RR. Other human transporters (BCRP, BSEP, MRP1,3,5, MDR1) tested in this study did not exhibit interaction with MC. Although MRP2 showed specific MC transport, the MC-LR-GSH conjugate, was not transported suggesting the involvement of other transporters than MRP2 for the conjugate efflux.


Assuntos
Glutationa/química , Microcistinas/metabolismo , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Benzobromarona/química , Benzobromarona/metabolismo , Cromatografia Líquida de Alta Pressão , Células HEK293 , Hepatócitos/citologia , Hepatócitos/metabolismo , Humanos , Microcistinas/análise , Proteínas Associadas à Resistência a Múltiplos Medicamentos/antagonistas & inibidores , Transportadores de Ânions Orgânicos/genética , Transportadores de Ânions Orgânicos/metabolismo , Espectrometria de Massas em Tandem
7.
Se Pu ; 37(7): 723-728, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31271011

RESUMO

A method was developed for the determination of cylindrospermopsin (CYN), nodularin (NOD), microcystin-RR (MC-RR), microcystin-YR (MC-YR) and microcystin-LR (MC-LR) in freshwater fish by dispersive solid phase extraction-liquid chromatography-tandem mass spectrometry (DSPE-LC-MS/MS). The analytes were extracted from fish tissues with acetonitrile-water-formic acid (89:10:1, v/v/v), and purified by DSPE using C18 as the adsorbent. The separation of analytes was performed on an Agilent ZORBAX Eclipse XDB C18 column with the gradient elution of acetonitrile and water as mobile phases. Qualitative analysis was performed using the multiple reaction monitoring (MRM) mode. The analytes were quantified by matrix-matched external standard curves. The chromatographic and MS parameters were optimized. Major factors affecting the extraction and cleanup efficiencies including the type of extraction solvent and cleanup sorbent were investigated. The linear correlation coefficients (R2) of the five target compounds were no less than 0.9954. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) of the five target compounds were 5-10 µg/kg and 15-40 µg/kg, respectively. The spiked recoveries of the five target compounds ranged from 62.3% to 101.2%. The developed method is simple, rapid, accurate, sensitive, and is suitable for the determination of cylindrospermopsin, nodularin and microcystins in freshwater fish.


Assuntos
Toxinas Bacterianas/análise , Peixes , Contaminação de Alimentos/análise , Microcistinas/análise , Peptídeos Cíclicos/análise , Uracila/análogos & derivados , Animais , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Água Doce , Extração em Fase Sólida , Espectrometria de Massas em Tandem , Uracila/análise
8.
Talanta ; 202: 279-284, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31171183

RESUMO

Microcystin-LR (MC-LR) is a potent hepatotoxin that is often associated with blooms of cyanobacteria. The analysis of trace MC-LR plays important role in environmental and health fields. Herein, we developed a low-cost and enzyme-free detection method of MC-LR by using hairpin DNA-templated copper nanoclusters (hpDNA-CuNCs) as fluorescent probe. The hpDNA-template was designed and fabricated by a MC-LR aptamer loop and a double strand stem, which can specifically recognize target MC-LR with strong affinity. The AT-rich and complementary double strand stem serves as a template for the formation of CuNCs. The formed fluorescent sensing probe of hpDNA-CuNCs exhibits maximum emission wavelength at 575 nm. Upon the addition of target MC-LR into the hpDNA-CuNCs, we observed fluorescence was quenched considerably due to the high affinity between MC-LR and hpDNA aptamer strand loop, which indicated a conformational change of hairpin probe from the stem-loop DNA structure to single-stranded DNA. Then, the change of fluorescence intensity can be used to monitor the concentration of MC-LR from 0.005 to 1200 µg L-1 with a detection limit of 0.003 ng L-1. Compared with the previous reports, this method does not require complex DNA sequence design, fluorescence dye label and sophisticated experimental techniques. Moreover, the target MC-LR in real water samples has been detected.


Assuntos
Técnicas Biossensoriais , Cobre/química , DNA/química , Fluorescência , Corantes Fluorescentes/química , Nanopartículas Metálicas/química , Microcistinas/análise , Poluentes Químicos da Água/análise , Corantes Fluorescentes/síntese química , Espectrometria de Fluorescência
9.
Sci Total Environ ; 688: 380-388, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31233918

RESUMO

In freshwater aquaculture ponds, cyanobacterial blooms and microcystins (MCs) pollution have attracted considerable attention due to their toxic effects. To provide an insight into cyanobacterial problems in aquaculture ponds, MCs distribution, bioaccumulation, and Microcystis genotype succession in a fishpond were investigated from May 2017 to November 2017. The distribution of MCs in filtered water, seston, and sediment varied considerably among months. MCs concentrations in filtered water, seston, and sediment ranged from 1.16 to 3.66 µg/L, 0.64 to 13.98 µg/g DW, and 1.34 to 5.90 µg/g DW, respectively. In addition, chemical oxygen demand was positively correlated with sestonic MCs concentrations. MCs concentrations accumulated in different tissues of market-size fish were in the order of liver > kidney > intestine > muscle. MCs content in muscle was 4.3 times higher than the WHO recommended tolerable daily intake level. Twenty-four ITS genotypes of Microcystis were identified from a total of 653 sequences. During the survey period, considerable genotype variation and rapid genotype succession were observed and dominant genotype was absent. A redundancy analysis revealed that Microcystis genotypes could significantly influence the variations in the proportions of the potentially toxic Microcystis, which could in turn influence the MCs concentrations in seston.


Assuntos
Aquicultura , Monitoramento Ambiental , Microcistinas/análise , Microcystis/genética , Animais , Peixes , Microcystis/crescimento & desenvolvimento
10.
Biosensors (Basel) ; 9(2)2019 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-31216673

RESUMO

Cyanobacterial blooms cause local and global health issues by contaminating surface waters. Microcystins and nodularins are cyclic cyanobacterial peptide toxins comprising numerous natural variants. Most of them are potent hepatotoxins, tumor promoters, and at least microcystin-LR is possibly carcinogenic. In drinking water, the World Health Organization (WHO) recommended the provisional guideline value of 1 µg/L for microcystin-LR. For water used for recreational activity, the guidance values for microcystin concentration varies mostly between 4-25 µg/L in different countries. Current immunoassays or lateral flow strips for microcystin/nodularin are based on indirect competitive method, which are generally more prone to sample interference and sometimes hard to interpret compared to two-site immunoassays. Simple, sensitive, and easy to interpret user-friendly methods for first line screening of microcystin/nodularin near water sources are needed for assessment of water quality and safety. We describe the development of a two-site sandwich format lateral-flow assay for the rapid detection of microcystins and nodularin-R. A unique antibody fragment capable of broadly recognizing immunocomplexes consisting of a capture antibody bound to microcystins/nodularin-R was used to develop the simple lateral flow immunoassay. The assay can visually detect the major hepatotoxins (microcystin-LR, -dmLR, -RR, -dmRR, -YR, -LY, -LF -LW, and nodularin-R) at and below the concentration of 4 µg/L. The signal is directly proportional to the concentration of the respective toxin, and the use of alkaline phosphatase activity offers a cost efficient alternative by eliminating the need of toxin conjugates or other labeling system. The easy to interpret assay has the potential to serve as a microcystins/nodularin screening tool for those involved in water quality monitoring such as municipal authorities, researchers, as well as general public concerned of bathing water quality.


Assuntos
Toxinas Bacterianas/análise , Cianobactérias/química , Imunoensaio/instrumentação , Microcistinas/análise , Peptídeos Cíclicos/análise , Carcinógenos/análise , Desenho de Equipamento , Fitas Reagentes/análise , Água/análise
11.
Chemosphere ; 229: 538-548, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31100625

RESUMO

In the present work, the degradation of three cyanotoxins from the hepatotoxins group was investigated under laboratory-controlled experiments in water samples. Surface waters spiked with microcystin-LR (MC-LR), nodularin (NOD) and cylindrospermopsin (CYN) were subjected to hydrolysis, chlorination and photo-degradation, under both sunlight (SL) and ultraviolet (UV) radiation. A total of 12 transformation products (TPs) were detected and tentatively identified by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF MS). These comprised: 6 chlorination TPs (3 from CYN and 3 from MC-LR, 2 isomers); 4 UV TPs (all from CYN); and 2 sunlight TPs (one isomer from MC-LR and another from NOD). No TPs were observed under hydrolysis conditions. The chemical structures for all TPs were tentatively proposed based on the accurate-mass QTOF MS full-spectra. Analysis of real-world samples collected from the Peñol reservoir (Antioquia, Colombia) revealed the presence of MC-LR and CYN as well as a sunlight TP identified in the laboratory experiments. Data presented in this article will assist further research on TPs potentially formed in future tertiary degradation processes applied for the removal of organic micro-pollutants in water; as well as improving available knowledge on the toxic implications of cyanobacterial toxins TPs in surface waters.


Assuntos
Toxinas Bacterianas/química , Microcistinas/química , Peptídeos Cíclicos/química , Uracila/análogos & derivados , Poluentes Químicos da Água/química , Toxinas Bacterianas/análise , Cromatografia Líquida/métodos , Colômbia , Halogenação , Hidrólise , Espectrometria de Massas , Microcistinas/análise , Peptídeos Cíclicos/análise , Luz Solar , Raios Ultravioleta , Uracila/análise , Uracila/química , Poluentes Químicos da Água/análise
12.
Electrophoresis ; 40(14): 1805-1811, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31106441

RESUMO

Microcystins are a group of cyanotoxins which interact with the C-terminal region of PP1 and PP2A proteins, so denaturation and inactivation are necessary for breaking covalent binding to release microcystins. In this study, a novel extraction method was developed by laser irradiation desorption of microcystins from fish protein. The sample was mixed with aqueous methanol and irradiated by a 450 nm laser, with an optimized value of laser power density at 8 W and exposure time at 5 min. ThenLC-MS/MS was applied for the determination of microcystins in fish extracts. The ionization behaviors of microcystins were investigated firstly, and doubly charged microcystins were selected as precursor ions in multiple reaction monitoring scan for quantification. This proposed quantitative method was well validated in terms of selectivity, linearity, sensitivity, accuracy, recovery, and stability. The successful application of this LC-MS/MS method showed its ability for the analysis of microcystins in low concentration, and it would be of significant interest for environmental and food safety applications to ensure the safety of fish and related products.


Assuntos
Proteínas de Peixes/química , Peixes , Microcistinas/análise , Animais , Técnicas Biossensoriais/métodos , Cromatografia Líquida de Alta Pressão/métodos , Inocuidade dos Alimentos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Espectrometria de Massas em Tandem
13.
Anal Bioanal Chem ; 411(20): 5267-5275, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31129692

RESUMO

Microcystins are cyclic peptide toxins with hepatotoxic and tumor-promoting properties, which are produced in significant quantities (up to tens of µg/L) in freshwater cyanobacterial water blooms. Several studies reported microcystin accumulation in fish with possible food transfer to humans. These compounds are further metabolized to cysteine and glutathione conjugates which can be present in tissues in significant concentrations. In this study, we focused on the development and evaluation of robust and highly sensitive SPE-LC-MS/MS method for the analysis of microcystin conjugates in fish tissue samples. For the first time, we demonstrate the use of isotopically labeled internal standards which are essential for accurate and precise determination of analytes in complex biotic matrices. LLOQs of respective microcystin conjugates (signal-to-noise ratio; S/N > 10, peak-to-peak method) ranged from 3.3 to 5.0 ng/g of tissue fresh weight (FW). The calibration was linear within a range of concentrations from 1 to 70 ng/mL for all analyzed conjugates. The precision and repeatability of the method were very good with recoveries in the range of 88.5-107.6% and relative standard deviations between 8.8 and 13.2% for all analytes. In the follow-up study, fully validated method was used for the determination of microcystin conjugate levels in common carp exposed to microcystin-containing cyanobacterial biomass under controlled conditions. Significant amounts of microcystin conjugates (up to 55 ng/g) were found in the tissues of fish after 7 weeks of exposure. Our method was shown to be robust, sensitive, selective, and suitable for the determination of trace levels of microcystin conjugates in fish tissues.


Assuntos
Cromatografia Líquida/métodos , Cianobactérias/química , Cisteína/análise , Glutationa/análise , Microcistinas/análise , Espectrometria de Massas em Tandem/métodos , Biomassa , Limite de Detecção , Microcistinas/química , Técnica de Diluição de Radioisótopos , Reprodutibilidade dos Testes
14.
Chemosphere ; 229: 332-340, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31078890

RESUMO

In freshwater aquaculture ecosystems with high-frequency occurrences of cyanobacteria blooms, a chronic neurotoxic cyanobacteria toxin, ß-N-methylamino-l-alanine (BMAA), is a new pollutant that affects the normal growth, development, and reproduction of aquaculture organisms. BMAA poses a great threat to the food quality and food safety of aquatic products. In this paper, high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) was used to detect the contents of BMAA in the edible portions of six representative freshwater aquaculture products (Corbicula fluminea, Anodonta arcaeformis, Macrobrachium nipponense, Eriocheir sinensis, Ctenopharyngodon idella, and Mylopharyngodon piceus) from Taihu Lake Basin in China. Noncarcinogenic health risks were assessed with reference to the model recommended by the International Environmental Modelling and Software Society and based on the biomagnification characteristics of BMAA in the various aquaculture products investigated by the stable nitrogen isotope technique. The average BMAA concentrations in the edible portions of the six freshwater culture products were from 2.05 ±â€¯1.40 to 4.21 ±â€¯1.26 µg g-1 dry weight (DW), and the difference was significant (p < 0.05), such a difference increased with the increase in the trophic level in the aquaculture products. Although a biomagnification indication was observed, the trophic magnification factor (TMF) was only 1.20 which exhibited a relatively low biomagnification efficiency. The annual health risk values of BMAA in all the measured aquatic products were within the maximum tolerable range (<1 × 10-6 a-1), and the health risk increased with the increase in the trophic level. The risk values of BMAA in the six freshwater aquaculture products for children was slightly higher than the negligible level (<1 × 10-7 a-1), thus there might have potential health risks for children's long-term consumption. Considering China's national conditions, the guidance values of BMAA based on the quality and safety of freshwater aquaculture products were proposed to be 7.2 µg g-1 DW for adults and 1.8 µg g-1 DW for children.


Assuntos
Diamino Aminoácidos/análise , Aquicultura/métodos , Toxinas Bacterianas/análise , Lagos/química , Toxinas Marinhas/análise , Microcistinas/análise , Medição de Risco , Adulto , Diamino Aminoácidos/normas , Aquicultura/normas , Criança , China , Cromatografia Líquida de Alta Pressão , Inocuidade dos Alimentos , Humanos , Neurotoxinas/análise , Espectrometria de Massas em Tandem
15.
Sci Total Environ ; 670: 971-981, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31018439

RESUMO

In the past, the versatility of a biosand filter has been successfully checked to counter suspended solids, metals, dissolved organic carbon (DOC), coliforms and other water quality parameters (WQPs) from the drinking water sources. In this study, cyanotoxin in the form of microcystin-LR (MC-LR) along with above-mentioned WQPs including nitrate, nitrite, and ammonia are analyzed for their removal using agro-residue based biosand filters (ARSFs) for 49 days (7 cycles). Three different agro-residue materials (ARMs) viz. deinking sludge (DSF), hemp fiber (HFF) and paper-pulp dry sludge (PPF) were used as the support material (top 5 cm) along with sand (49 cm) as the primary filter media to enhance the overall bioactivity. This enhancement in bioactivity is hypothesized to remove more MC-LR, DOC, coliform along with efficient nitrification/denitrification. Native bacterial community isolated from the filtration unit of a drinking water treatment plant (Chryseobacterium sp. and Pseudomonas fragi = X) along with the MC-LR-degrader: Arthrobacter ramosus (which was screened as the best biofilm-former among two other MC-LR-degraders tested) were used to inoculate the filters (all three ARSFs). Overall, DSF performed the best among all the ARSFs when compared to the sand filter (SFI) inoculated with the same bacterial strains (A + X). An increase in the bioactivity for ARSFs, particularly DSF was evident from the DOC removal (44 ±â€¯11%, 15% more than SFI), coliform removal (92.7 ±â€¯12.8%, 24% more than SFI), MC-LR removal (87 ±â€¯14%, 13% more than SFI) and an effective nitrification/denitrification, reducing ammonia, nitrate and nitrite level to below guideline values. Toxic assessment using bioindicator (Rhizobium meliloti) revealed safe filter water only in case of DSF.


Assuntos
Água Potável/análise , Filtração/métodos , Resíduos Industriais , Microcistinas/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Qualidade da Água , Agricultura , Arginina/análise , Filtração/instrumentação , Leucina/análise , Compostos Orgânicos/análise
16.
J Agric Food Chem ; 67(21): 6041-6047, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31017431

RESUMO

A multiplex immunochromatographic assay (ICA) based on dual-color fluorescent microspheres (FMs) as a sensitive label was developed for the first time. Two typical algae toxins, microcystin-LR (MC-LR) and okadaic acid (OA), were chosen as proof-of concept targets to evaluate the feasibility of this ICA format. Commercial red- and green-colored FMs were selected to couple with monoclonal antibodies as fluorescent probes. The use of dual-wavelength FMs as labels guaranteed a lower consumption of material strips, lower sample volume, and shorter reaction time without increasing the length of ICA strips. Under optimal conditions, the multiplex FM-ICA could be completed in 20 min and reached limits of detection for the simultaneous determination of MC-LR and OA in fish samples, which were 0.074 and 2.42 µg/kg, respectively. The developed technique was validated using artificially spiked and naturally contaminated fish samples. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used as confirmatory technique. In summary, this portable ICAs detection mode based on dual-wavelength FMs provided a reliable and sensitive on-site detection of multiple contaminants in food samples, which opens a new field for application of FMs in food safety.


Assuntos
Contaminação de Alimentos/análise , Imunoensaio/métodos , Microcistinas/análise , Ácido Okadáico/análise , Alimentos Marinhos/análise , Animais , Peixes , Fluorescência , Imunoensaio/instrumentação , Limite de Detecção , Microesferas
17.
J Chromatogr A ; 1599: 66-74, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-30961962

RESUMO

Cyanobacteria can form dense blooms under specific environmental conditions, and some species produce secondary metabolites known as cyanotoxins, which present significant risks to public health and the environment. Identifying toxins produced by cyanobacteria present in surface water and fish is critical to ensuring high quality food and water for consumption, and protectionn of recreational uses. Current analytical screening methods typically focus on one class of cyanotoxins in a single matrix and rarely include saxitoxin. Thus, a cross-class screening method for microcystins, nodularin, anatoxin-a, cylindrospermopsin, and saxitoxin was developed to examine target analytes in environmental water and fish tissue. This was done, due to the broad range of cyanotoxin physicochemical properties, by pairing two extraction and separation techniques to improve isolation and detection. For the first time a zwitterionic hydrophilic interaction liquid chromatography column was evaluated to separate anatoxin-a, cylindrospermopsin, and saxitoxin, demonstrating greater sensitivity for all three compounds over previous techniques. Further, the method for microcystins, nodularin, anatoxin-a, and cylindrospermopsin were validated using isotopically labeled internal standards, again for the first time, resulting in improved compensation for recovery bias and matrix suppression. Optimized extractions for water and fish tissue can be extended to other congeners in the future. These improved separation and isotope dilution techniques are a launching point for more complex, non-targeted analyses, with preliminary targeted screening.


Assuntos
Cromatografia Líquida , Monitoramento Ambiental/métodos , Peixes , Toxinas Marinhas/análise , Espectrometria de Massas em Tandem , Água/química , Animais , Toxinas Bacterianas/análise , Cianobactérias/química , Isótopos/análise , Microcistinas/análise , Peptídeos Cíclicos/análise , Saxitoxina/análise , Tropanos/análise , Uracila/análogos & derivados , Uracila/análise
18.
Sci Total Environ ; 666: 1292-1300, 2019 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-30970494

RESUMO

Microcystins (MCs) appear during harmful algal blooms (HABs) in water sources worldwide, and represent a threat for humans and animals ingesting or inhaling MCs from the environment. Herein, treated rice husk (RH) was tested as a recyclable sorbent for removal of six MCs (MC-RR, MC-LR, MC-YR, MC-LA, MC-LF, and MC-LW) from water. RH was refluxed with hydrochloric acid and heated to 250 °C to produce the sorbent material. Twenty milligrams of treated RH removed >95% of the MCs from a 30 mL solution containing 25 µg/L of each MC. The adsorption of MCs onto RH follows the Freundlich isotherm model (R2 ≥ 0.9612) and pseudo-second-order kinetics (R2 ≥ 0.9996). More than 90% of MCs were removed within 5 min, and >95% were removed at equilibrium (in <40 min). Performance of the RH sorbent was evaluated by removing MCs from Lake Erie water collected during an algal bloom in 2017. The total concentration (extracellular plus intracellular) of six tested MCs in lake water ranged from 3.7 to 13,605.9 µg/L, and removal of MCs by treated RH ranged from 100.0% to 71.8%, respectively. The removal capacity of RH for the six MCs from the lake water sample containing 13,605.9 µg/L of MCs was 586 µg per g of treated RH. After being used to extract MCs, the RH was heated to 560 °C to produce silica nanoparticles. Therefore, treated RH enables rapid and efficient removal of MCs from water and it can be recycled for use as a raw material. Overall, treated RH can contribute to mitigation of environmental and health effects caused by MCs and reduce concerns for toxic waste disposal.


Assuntos
Água Potável/análise , Lagos/análise , Microcistinas/análise , Oryza/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Água Potável/microbiologia , Proliferação Nociva de Algas , Lagos/microbiologia , Purificação da Água/instrumentação
19.
Aquat Toxicol ; 211: 81-91, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30954847

RESUMO

The excessive proliferation of toxin producing cyanobacteria constitutes a significant health risk to the environment and humans. This is due to the contamination of potable water and accumulation of cyanotoxins in plant and animal tissues. As a means of controlling bloom forming cyanobacteria, secondary metabolites with pro-oxidative activities from plants are used to treat water bodies contaminated with cyanobacterial blooms and their associated toxins. The objective of the present study was to evaluate the mechanism of action of extract, fractions and isolated flavonoids of Tridax procumbens L. on Microcystis aeruginosa (Kützing) Kützing. by monitoring changes in growth, oxidative stress, antioxidant response, and cyanatoxin microcystins (MCs) production. The extract, fraction 3 and the isolated flavonoids significantly reduced the cell density of the cyanobacterium. Furthermore, the extract and fraction 3 increased the production of reactive oxygen species, induced lipid peroxidation, and altered antioxidant enzyme activities of M. aeruginosa. The total MCs content of the cyanobacterium was negatively affected by the presence of the extract, fractions and isolated flavonoids. The present study show that T. procumbens has secondary metabolites that are capable of interfering with the physiology and microcystins production of M. aeruginosa. These characteristics are promising for the control of this noxious cyanobacterium in aquatic ecosystems.


Assuntos
Asteraceae/química , Flavonoides/farmacologia , Microcistinas/análise , Microcystis/efeitos dos fármacos , Extratos Vegetais/química , Poluentes Químicos da Água/análise , Animais , Antioxidantes/metabolismo , Relação Dose-Resposta a Droga , Flavonoides/isolamento & purificação , Peroxidação de Lipídeos/efeitos dos fármacos , Microcystis/crescimento & desenvolvimento , Microcystis/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
20.
Ecotoxicol Environ Saf ; 176: 20-26, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-30947029

RESUMO

Microcystins is a class of monocyclic of heptapeptides with many different isomerides. It has become potential hazardous material in water environment for its toxic, distribution and stability. This project worked on a method for determination of trace microcystin (MC-LR and MC-RR) in environmental waters. The ionic liquid magnetic graphene (IL@MG) was prepared and applied to the concentration and determination of microcystins, based on magnetic solid phase extraction (MSPE), and coupled with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The ionic liquid magnetic graphene was prepared by coprecipitatial synthesis and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), specific surface area (BET), pore size distribution (BJH) and magnetic hysteresis loop. The experimental parameters of magnetic solid phase extraction, including amount of IL@MG, pH, extraction time and elution solvent were investigated by a univariate method and orthogonal screening. The method showed good linearity in the range of 0.01-10.0 g/L and 0.005-10.0 µg/L for MC-LR and MC-RR, when the pH of water samples was 4.00 and 10.0 mg adsorbents were used to extract targets for 18 min. The lowest detection limit was 0.414 ng/L and 0.216 ng/L for MC-LR and MC-RR respectively. The recoveries of the microcystins were in the range of 83.6-100.9%, and the relative standard deviation was less than 7.59%. The trace amount of MC-LR (0.020 µg/L) and MC-RR (0.003 µg/L and 0.021 µg/L) was detected in actural water samples. Attributed to its simple operator, low detection limit and high sensitivity, this method could be used for the detection of trace microcystins in water samples.


Assuntos
Monitoramento Ambiental/métodos , Grafite/química , Microcistinas/análise , Cromatografia Líquida de Alta Pressão , Líquidos Iônicos/química , Limite de Detecção , Magnetismo , Microcistinas/química , Microscopia Eletrônica de Varredura , Extração em Fase Sólida , Solventes , Espectroscopia de Infravermelho com Transformada de Fourier , Espectrometria de Massas em Tandem
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