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1.
Chemosphere ; 241: 125091, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31683442

RESUMO

Soil columns were collected from a blueberry field, and insecticide solutions were allowed to leach through these columns. Insecticides from four different chemical classes were applied at two different rates: the concentration at which the insecticides wash off blueberries under rainfall conditions and the labeled field rate at which they are sprayed. The soil columns were divided into thirds; top, middle and bottom. Soil bioassays using Eisenia foetida Savigny, as an indicator species, were set up to determine the toxicity of the insecticides at a top, middle and bottom layer of the soil column. The mass of E. foetida was also measured after the bioassay experiment was completed. The concentrations at which insecticides wash-off of blueberries from rainfall were not lethal to E. foetida. In order to support mortality data, insecticide residues were quantified in the soil layers for each insecticide. Under field rate leaching conditions, carbaryl showed the high levels of toxicity in the top and middle layers of soil suggesting that it has the highest risk to organisms from leaching. This study will help blueberry growers make informed decisions about insecticide use, which can help minimize contamination of the environment.


Assuntos
Mirtilos Azuis (Planta)/crescimento & desenvolvimento , Inseticidas/análise , Inseticidas/toxicidade , Oligoquetos/efeitos dos fármacos , Poluentes do Solo/toxicidade , Animais , Carbaril/análise , Carbaril/toxicidade , Produtos Agrícolas/crescimento & desenvolvimento , Ecotoxicologia , Michigan , Resíduos de Praguicidas/análise , Chuva , Solo/química , Poluentes do Solo/análise
2.
Food Chem ; 309: 125659, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31734005

RESUMO

This research aimed to compare the efficiency of five washing solutions (0.9% NaCl, 0.1% NaHCO3, DI water, 0.001% KMnO4, and 0.1% acetic acid) for removing carbaryl residues from cucumber and chili. The vegetables were soaked in 10 mg/L of carbaryl solution for 30 min and then washed for 30 min in one of the five washing solutions and the results compared. Each experiment was performed in triplicate and the amounts of carbaryl residues remaining were determined using high-performance liquid chromatography (HPLC). The results showed that 0.001% KMnO4 was the most effective at removing carbaryl from both vegetables. Washing with 0.001% KMnO4 reduced carbaryl residues to 64% and 28%, respectively, of the original concentrations. Washing with DI water was the least effective method of removing carbaryl residues. Hopefully, the results will encourage further research, into reducing carbaryl contamination by washing with chemical solutions, which will enable producers to reduce pesticide residues.


Assuntos
Carbaril/análise , Cromatografia Líquida de Alta Pressão , Cucumis sativus/química , Resíduos de Praguicidas/análise , Soluções/química , Ácido Acético/química , Carbaril/isolamento & purificação , Cucumis sativus/metabolismo , Contaminação de Alimentos/análise , Resíduos de Praguicidas/isolamento & purificação , Bicarbonato de Sódio/química , Cloreto de Sódio/química , Água/química
3.
Mater Sci Eng C Mater Biol Appl ; 102: 764-772, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31147049

RESUMO

A novel electrochemical sensor based on the reduced graphene oxide-Cu/CuO-Ag nanocomposite modified glassy carbon electrode (rGO/Cu/CuO-Ag/GCE) has been applied for the simultaneous analysis of carbaryl and fenamiphos as two important pesticides. The electrochemical behavior of carbaryl and fenamiphos at rGO/Cu/CuO-Ag/GCE was studied by cyclic voltammetry and differential pulse voltammetry. The modified electrode exhibited two separated oxidation signals for the simultaneous determination of both carbaryl and fenamiphos with excellent sensitivity. The characteristics of the modified electrode were studied with transmission electron microscopy, X-ray diffraction and Fourier transform-infrared spectroscopy techniques. Under optimized conditions, the rGO/Cu/CuO-Ag/GCE detected carbaryl and fenamiphos with the wide linear ranges of 0.05-20 and 0.01-30 µM, and the detection limits were 0.005 and 0.003 µM, respectively. This developed electrochemical platform applied as a simple and cost-effective sensor for the detection of low levels of carbaryl and fenamiphos in fruit and vegetable samples successfully.


Assuntos
Carbaril/análise , Cobre/química , Técnicas Eletroquímicas/métodos , Grafite/química , Nanocompostos/química , Compostos Organofosforados/análise , Praguicidas/análise , Prata/química , Espectroscopia Dielétrica , Eletrodos , Vidro/química , Concentração de Íons de Hidrogênio , Nanocompostos/ultraestrutura , Oxirredução , Reprodutibilidade dos Testes , Verduras/química
4.
J Sci Food Agric ; 99(9): 4383-4390, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30851058

RESUMO

BACKGROUND: The variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health. RESULTS: VHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL-1 and a limit of detection (LOD) of 0.3 ng mL-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g-1 in rice and maize and 72 ng g-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively. CONCLUSION: The VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution. © 2019 Society of Chemical Industry.


Assuntos
Carbaril/análise , Ensaio de Imunoadsorção Enzimática/métodos , Inseticidas/análise , Triticum/química , Zea mays/química , Animais , Camelídeos Americanos , Grão Comestível/química , Contaminação de Alimentos/análise , Cadeias Pesadas de Imunoglobulinas/análise , Cadeias Pesadas de Imunoglobulinas/imunologia , Limite de Detecção , Anticorpos de Cadeia Única/análise , Anticorpos de Cadeia Única/imunologia
5.
Anal Biochem ; 572: 9-15, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30831096

RESUMO

Immunoassays provide a high-throughput method for monitoring pesticides in foods and the environment. Due to easy generation and capable of being manipulated, chicken single-chain variable fragment (scFv) is attractive in the development of immunoassays for pesticides. Two scFvs (X1 and X2) against the insecticide carbaryl were generated from a chicken immunized with hapten C1 conjugated to keyhole limpet hemocyanin and fused with alkaline phosphatase (AP) to develop a rapid one-step enzyme-linked immunosorbent assay for this pesticide. X2-AP showed higher binding affinity to carbaryl than X1-AP. The X2-AP-based ELISA had a half-maximum signal inhibition concentration of 15 ng mL-1 and a limit of detection of 1.6 ng mL-1. This assay showed negligible cross-reactivity with other carbamate pesticides (<0.1%) and low cross-reactivity with 1-naphthol (5%). The average recoveries of carbaryl spiked in soil, apple and pear samples by the one-step assay ranged from 90% to 114% and agreed well with those of high-performance liquid chromatography. The chicken scFv-based assay showed promise as a high-throughput screening tool for carbaryl in environmental and food matrices.


Assuntos
Carbaril/análise , Imunoensaio/métodos , Inseticidas/análise , Anticorpos de Cadeia Única/imunologia , Fosfatase Alcalina/química , Fosfatase Alcalina/metabolismo , Animais , Carbaril/imunologia , Galinhas , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Inseticidas/imunologia , Limite de Detecção , Pyrus/química , Pyrus/metabolismo , Anticorpos de Cadeia Única/química , Solo/química
6.
Appl Microbiol Biotechnol ; 103(7): 3205-3213, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30770965

RESUMO

Transcriptional regulatory proteins (TRPs)-based whole-cell biosensors are promising owing to their specificity and sensitivity, but their applications are currently limited. Herein, TRPs were adapted for the extracellular detection of a disease biomarker, uric acid, and a typical pesticide residue, carbaryl. A mutant regulatory protein that specifically recognizes carbaryl as its non-natural effector and activates transcription upon carbaryl binding was developed by engineering the regulatory protein TtgR from Pseudomonas putida. The TtgR mutant responsive to carbaryl and a regulatory protein responsive to uric acid were used for in vitro detection, based on their allosteric binding of operator DNA and inducer molecules. Based on the quantitative polymerase chain reactions (qPCRs) output, the minimum detectable concentration was between 1 nM-1 µM and 1-10 nM for uric acid and carbaryl, respectively. Our results demonstrated that engineering the effector specificity of regulatory proteins is a potential technique for generating molecular recognition elements for not only in vivo but also in vitro applications.


Assuntos
Proteínas de Bactérias/genética , Biomarcadores/análise , Resíduos de Praguicidas/análise , Proteínas Repressoras/genética , Proteínas de Bactérias/isolamento & purificação , Sítios de Ligação , Carbaril/análise , Mutação , Reação em Cadeia da Polimerase , Pseudomonas putida/genética , Fatores de Transcrição/genética , Ácido Úrico/análise
7.
Anal Chim Acta ; 1038: 79-86, 2018 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-30278910

RESUMO

This paper reports on a novel ultrasonic injection port designed and constructed to analyze thermally unstable chemical compounds using corona discharge ion mobility spectrometry (CD-IMS). In order to achieve the highest possible efficiency with the device, some parameters such as the solvent type, carrier gas flow rate and sample volume were exhaustively investigated. Through a comparative study conducted, it was revealed that unlike the thermal desorption system, the proposed ultrasonic injection port could easily be used for the analysis of some thermally unstable compounds such as carbaryl, propoxur and vitamin B1, by means of CD-IMS. To evaluate the potential of the device, carbaryl, extracted from different samples by dispersive liquid-liquid microextraction technique, was quantitatively analyzed. The CD-IMS-based results brought forth the detection limit of 0.03 mg L-1, and dynamic range of 0.1-10.0 mg L-1 with the determination coefficient of 0.9981. The relative standard deviations for one day and three consecutive days were 4 and 6%, respectively. Further, the spiked samples of agricultural wastewater, underground water, and tomato analyzed culminated in the recovery values of 83%, 98% and 82%, respectively. The satisfactory results proved an acceptable capability of the sample introduction system, to be conveniently used for routine analysis of thermally unstable compound, without any tedious derivatization.


Assuntos
Carbaril/análise , Eletroporação , Espectrometria de Mobilidade Iônica , Propoxur/análise , Temperatura , Tiamina/análise , Ultrassom , Eletrodos , Eletroporação/instrumentação , Desenho de Equipamento
8.
Talanta ; 186: 389-396, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-29784378

RESUMO

An electrochemical screening assay for the detection of phenyl carbamates (i.e. carbaryl, carbofuran, isoprocarb and fenobucarb) was developed and applied to grains samples (i.e. durum wheat, soft wheat and maize). Nano carbon black (CB) was strategically employed to realize an effective, reproducible, fouling resistant, low cost, delocalisable screen printed sensor (CB-SPE). CB-SPEs morphology (SEM and FEM) and electrochemical property (CV and EIS) were studied. The final pesticides analysis protocol consist of: (i) extraction of the analyte (just by mixing), (ii) alkaline hydrolysis (10 min R.T.), (iii) DPV detection directly of 100 µL of extract on the CB-SPE surface. Linear range between 1.0 × 10-7 and 1.0 × 10-4 mol L-1, good determination coefficients (R2 ≥ 0.9971) and satisfactory sensitivity (≥ 3.90 × 10-1 A M-1 cm-2) and LODs (≤ 8.0 × 10-8 mol L-1) were obtained for all the analytes. Excellent recoveries (78-102%) and accuracy (relative error vs. HPLC-MS/MS between 9.0% and -7.8%) resulted from the analysis of grains samples. The proposed CB-SPE based approach has demonstrated to be able to detect carbaryl at Maximum residue limits levels (MRLs), allowing class selective detection of commonly employed phenyl carbamates in food samples.


Assuntos
Carbamatos/análise , Carbaril/análise , Carbofurano/análise , Impressão , Nanopartículas/química , Fuligem/química , Triticum/química , Zea mays/química
9.
J Environ Sci Health B ; 53(7): 469-475, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29624471

RESUMO

Chlorpyrifos (O, O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) and carbaryl (1-naphthyl methylcarbamate) are often applied concurrently as insecticides in food production. The aim of this study was to research their migration behavior in a real environment. We researched the leaching of both pesticides by setting up field lysimeters on a farm with the typical soil used in fruit production today. In order to analyze the variables involved in this process, we performed complementary adsorption studies, we performed complementary adsorption studies using batches and undisturbed soil laboratory columns for both compounds. The results for pesticide transport through the lysimeters showed that less than 1% of chlorpyrifos was recovered in the leachates, while almost 17% was recovered for carbaryl. Having completed the experiment in undisturbed laboratory columns, soil analysis showed that chlorpyrifos mainly remained in the first 5 cm, while carbaryl moved down to the lower sections. These results can be explained in view of the sorption coefficient values (KD) obtained in horizons A and B for chlorpyrifos (393 and 184 L kg-1) and carbaryl (3.1 and 4.2 L kg-1), respectively. By integrating the results obtained in the different approaches, we were able to characterize the percolation modes of these pesticides in the soil matrix, thus contributing to the sustainable use of resources.


Assuntos
Carbaril/análise , Clorpirifos/análise , Poluentes do Solo/análise , Solo/química , Adsorção , Carbaril/química , Clorpirifos/química , Inseticidas/análise , Inseticidas/química , Poluentes do Solo/química
10.
Food Chem ; 240: 893-897, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-28946356

RESUMO

A biomimetic enzyme-linked immunosorbent assay (BELISA) which was based on molecularly imprinted polymers on paper (MIPs-paper) with specific recognition was developed. As a detector, the surface of paper was modified with γ-MAPS by hydrolytic action and anchored the MIP layer on γ-MAPS modified-paper by copolymerization to construct the artificial antibody Through a series of experimentation and verification, we successful got the MIPs-paper and established BELISA for the detection of carbaryl. The development of MIPs-paper based on BELISA was applied to detect carbaryl in real samples and validated by an enzyme-linked immunosorbent assay (ELISA) based on anti-carbaryl biological antibody. The results of these two methods (BELISA and ELISA) were well correlated (R2=0.944). The established method of MIPs-paper BELISA exhibits the advantages of low cost, higher stability and being re-generable, which can be applied as a convenient tool for the fast and efficient detection of carbaryl.


Assuntos
Carbaril/análise , Biomimética , Ensaio de Imunoadsorção Enzimática , Impressão Molecular , Polímeros
11.
J Environ Sci Health B ; 53(3): 161-170, 2018 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-29206083

RESUMO

Water quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21-1.51 ppm), nitrates (2.28-4.89 ppm) and phosphates (0.01-0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8-10 ppm), ammonia (0.02-0.22 ppm) and phenols (0.19-0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08-7.70) with a temperature of 17.8-21.2°C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18°C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.


Assuntos
Carbamatos/análise , Praguicidas/análise , Poluentes Químicos da Água/análise , Qualidade da Água , Carbamatos/química , Carbaril/análise , Carbaril/química , Carbofurano/análise , Carbofurano/química , Meia-Vida , Hidrólise , Quênia , Propoxur/análise , Propoxur/química , Chuva , Rios/química , Estações do Ano , Relação Estrutura-Atividade , Clima Tropical
12.
Bull Environ Contam Toxicol ; 98(5): 656-661, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28289805

RESUMO

Organochlorines and carbamates are common pesticides predominantly employed in agriculture. Large amounts of pesticides make their way into rivers and marine habitats. They accumulate in aquatic organisms through different exposure routes and gradually move up the food chain. Since contaminant bioaccumulation in animals is affected by several factors, this work harnessed several different approaches to explore the persistence of lindane, a long banned organochlorine pesticide, and carbaryl, a newer generation pesticide, in common sole (Solea solea), a major commercial species in Adriatic fisheries. Lindane was not only more accumulated than carbaryl in sole liver, but it was also detected in greater amount in muscle tissue, the edible part (lindane, 7 ± 4 ng/g; carbaryl, <0.004 ng/g w/w). Additional assays documented a greater accumulation of lindane in adults compared with juveniles and in specimens caught offshore than in those collected close to the coast. The present findings demonstrate the different accumulation dynamics of the two pesticides to confirm the benefits derived from the replacement of organochlorine pesticides with carbamate compounds.


Assuntos
Carbaril/farmacocinética , Linguados/metabolismo , Hexaclorocicloexano/farmacocinética , Praguicidas/farmacocinética , Poluentes Químicos da Água/farmacocinética , Animais , Carbaril/análise , Pesqueiros , Cadeia Alimentar , Hexaclorocicloexano/análise , Hidrocarbonetos Clorados/análise , Hidrocarbonetos Clorados/farmacocinética , Fígado/efeitos dos fármacos , Fígado/metabolismo , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Praguicidas/análise , Rios/química , Alimentos Marinhos/análise , Poluentes Químicos da Água/análise
13.
J Agric Food Chem ; 65(3): 666-674, 2017 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-28080039

RESUMO

In recent years, there have been increasing concerns about pesticide residues in various foods. On the other hand, there is growing attention in utilizing novel nanomaterials as highly sensitive, low-cost, and reproducible substrates for surface-enhanced Raman spectroscopy (SERS) applications. The objective of this study was to develop a SERS method for the rapid detection of pesticides that were extracted from different types of food samples (fruit juice and milk). A new SERS substrate was prepared by assembling gold nanorods into standing arrays on a gold-coated silicon slide. The standing nanorod arrays were neatly arranged and were able to generate a strong electromagnetic field in SERS measurement. The as-prepared SERS substrate was utilized to detect carbaryl in acetonitrile/water solution, fruit juices (orange and grapefruit), and milk. The results show that the concentrations of carbaryl spiked in fruit juice and milk were linearly correlated with the concentrations predicted by the partial least-squares (PLS) models with r values of 0.91, 0.88, and 0.95 for orange juice, grapefruit juice, and milk, respectively. The SERS method was able to detect carbaryl that was extracted from fruit juice and milk samples at a 50 ppb level. The detection limits of carbaryl were 509, 617, and 391 ppb in orange juice, grapefruit juice, and milk, respectively. All detection limits are below the maximum residue limits that were set by the U.S. EPA. Moreover, satisfactory recoveries (82-97.5%) were accomplished for food samples using this method. These results demonstrate that SERS coupled with the standing gold nanorod array substrates is a rapid, reliable, sensitive, and reproducible method for the detection of pesticide residues in foods.


Assuntos
Carbaril/análise , Contaminação de Alimentos/análise , Sucos de Frutas e Vegetais/análise , Ouro/química , Leite/química , Resíduos de Praguicidas/análise , Análise Espectral Raman/métodos , Animais , Bovinos , Nanotubos/química , Análise Espectral Raman/instrumentação
14.
Guang Pu Xue Yu Guang Pu Fen Xi ; 36(2): 541-4, 2016 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-27209765

RESUMO

Determination of carbaryl in rice by using Fourier transform far-infrared (FT- Far-IR) and terahertz time-domain spectroscopy (THz-TDS) combined with chemometrics was studied and the spectral characteristics of carbaryl in terahertz region was investigated. Samples were prepared by mixing carbaryl at different amounts with rice powder, and then a 13 mm diameter, and about 1 mm thick pellet with polyethylene (PE) as matrix was compressed under the pressure of 5-7 tons. Terahertz time domain spectra of the pellets were measured at 0.5~1.5 THz, and the absorption spectra at 1.6. 3 THz were acquired with Fourier transform far-IR spectroscopy. The method of sample preparation is so simple that it does not need separation and enrichment. The absorption peaks in the frequency range of 1.8-6.3 THz have been found at 3.2 and 5.2 THz by Far-IR. There are several weak absorption peaks in the range of 0.5-1.5 THz by THz-TDS. These two kinds of characteristic absorption spectra were randomly divided into calibration set and prediction set by leave-N-out cross-validation, respectively. Finally, the partial least squares regression (PLSR) method was used to establish two quantitative analysis models. The root mean square error (RMSECV), the root mean square errors of prediction (RMSEP) and the correlation coefficient of the prediction are used as a basis for the model of performance evaluation. For the R,, a higher value is better; for the RMSEC and RMSEP, lower is better. The obtained results demonstrated that the predictive accuracy of. the two models with PLSR method were satisfactory. For the FT-Far-IR model, the correlation between actual and predicted values of prediction samples (Rv) was 0.99. The root mean square error of prediction set (RMSEP) was 0.008 6, and for calibration set (RMSECV) was 0.007 7. For the THz-TDS model, R. was 0. 98, RMSEP was 0.004 4, and RMSECV was 0.002 5. Results proved that the technology of FT-Far-IR and THz- TDS can be a feasible tool for quantitative determination of carbaryl in rice. This paper provides a new method for the quantitative determination pesticide in other grain samples.


Assuntos
Carbaril/análise , Oryza/química , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia Terahertz , Calibragem , Análise dos Mínimos Quadrados
15.
Bull Environ Contam Toxicol ; 96(4): 423-31, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26754544

RESUMO

Surface water sampling in 2007-2010 measured the occurrence of carbamates and metalaxyl during base flow conditions and wet weather events in southern Ontario surface waters. Carbaryl, metalaxyl and pirimicarb were the most frequently detected compounds. In 2008 these three compounds were detected in over 50 % of the samples. Overall mean concentrations of carbaryl and metalaxyl over the course of the study (2007-2010) were 15 and 18 ng/L, respectively. Elevated concentrations of carbaryl (~100 to ~950 ng/L) appeared associated with wet weather (high flow) events, while highest concentrations of metalaxyl (~20-1330 ng/L) were correlated with base flow conditions. We attributed these observations as the result of runoff of carbaryl from the watershed during rain events, while metalaxyl contamination may have resulted primarily from spray drift.


Assuntos
Alanina/análogos & derivados , Carbamatos/análise , Carbaril/análise , Água Doce/química , Praguicidas/análise , Pirimidinas/análise , Poluentes Químicos da Água/análise , Alanina/análise , Monitoramento Ambiental , Água Doce/análise , Ontário , Chuva
16.
Toxicol Ind Health ; 32(6): 1135-42, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25342670

RESUMO

Cucumbers grown in two different greenhouses were exposed to mancozeb and carbaryl at different times. The effects of 10-day preharvest period, water and detergent washing, peeling, predetermined storage period at 4°C (refrigeration), and fermentation on the reduction of residue levels in the plant tissues were investigated. Mancozeb and carbaryl residues in cucumbers were determined by gas chromatography-electron capture detection. Results showed that residue levels in samples, which were collected after 10 days following the pesticide application, were significantly lower than the samples collected after 2 h subsequent to the pesticide application. The culinary applications were effective in reducing the residue levels of the pesticides in cucumbers. As a result, non-fermentative pickling in sodium chloride and acetic acid was the most effective way to reduce the mancozeb and carbaryl residues of the cucumbers.


Assuntos
Carbaril/análise , Cucumis sativus/química , Maneb/análise , Resíduos de Praguicidas/análise , Zineb/análise , Fermentação , Análise de Alimentos , Contaminação de Alimentos/análise , Armazenamento de Alimentos , Frutas/química
17.
J Agric Food Chem ; 63(20): 4966-72, 2015 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-25946094

RESUMO

A fluorescence sensing material based on quantum dots with excellent optical properties and molecularly imprinted polymer (QDs@MIP) with specific recognition has been developed. First the surface of CdSe/ZnS QDs was modified with ionic liquids (ILs) by electrostatic interaction. The fluorescence sensing material was constructed from anchoring the MIP layer on IL modified CdSe/ZnS QDs by copolymerization, which had been developed for the detection of carbaryl in rice and Chinese cabbage. The MIP fluorescence was more strongly quenched by carbaryl than the non-imprinted polymer (NIP) fluorescence, which indicated that the QDs@MIP could selectively recognize the corresponding carbaryl. Furthermore, the developed QDs@MIP method was validated by HPLC and ELISA respectively, and the results of these methods were well correlated (R(2) = 0.98). The fluorescence sensing material had obvious advantages, such as being easily prepared and having specific recognition and photostability. The developed method was simple and effective for the detection of carbaryl. And, it could also provide the technical support for the rapid detection in food safety fields.


Assuntos
Brassica/química , Carbaril/análise , Contaminação de Alimentos/análise , Inseticidas/análise , Medições Luminescentes/métodos , Oryza/química , Polímeros/química , Pontos Quânticos/química , Carbaril/isolamento & purificação , Fluorescência , Inseticidas/isolamento & purificação , Líquidos Iônicos/química , Impressão Molecular , Polímeros/síntese química
18.
Talanta ; 138: 86-99, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25863376

RESUMO

The simultaneous determination of two carbamate pesticides (carbaryl and carbendazim) and of the degradation product of carbaryl (1-naphthol) in iceberg lettuce was achieved by means of PARAFAC decomposition and excitation-emission fluorescence matrices. A standard addition method for a calibration based on four-way data was applied using different dilutions of the extract from iceberg lettuce as a fourth way that provided the enough variation of the matrix to carry out the four-way analysis. A high fluorescent overlapping existed between the three analytes and the fluorophores of the matrix. The identification of two fluorescent matrix constituents through the four-way model enabled to know the matrix contribution in each dilution of the extract. This contribution was subtracted from the previous signals and a subsequent three-way analysis was carried out with the tensors corresponding to each dilution. The PARAFAC decomposition of these resulting tensors showed a CORCONDIA index equal to 99%. For the identification of the analytes, the correlation between the PARAFAC spectral loadings and the reference spectra has been used. The trueness of the method, in the concentration range studied, was guaranteed because there was neither constant nor proportional bias according to the appropriate hypothesis tests. The best recovery percentages were obtained with the data from the most diluted extract, being the results: 127.6% for carbaryl, 125.55% for carbendazim and 87.6% for 1-naphthol. When the solvent calibration was performed, the decision limit (CCα) and the capability of detection (CCß) values, in x0=0, were 2.21 and 4.38 µg L(-1) for carbaryl, 4.87 and 9.64 µg L(-1) for carbendazim; and 3.22 and 6.38 µg L(-1) for 1-naphthol, respectively, for probabilities of false positive and false negative fixed at 0.05. However, these values were 5.30 and 10.49 µg L(-1) for carbaryl, 18.05 and 35.73 µg L(-1) for carbendazim; and 1.92 and 3.79 µg L(-1) for 1-naphthol, respectively, when the matrix-matched calibration using the most diluted extract was carried out in the recovery study.


Assuntos
Benzimidazóis/análise , Carbamatos/análise , Carbaril/análise , Análise Fatorial , Alface/química , Naftóis/análise , Praguicidas/análise , Espectrometria de Fluorescência/métodos , Calibragem , Corantes Fluorescentes
19.
J Food Sci ; 80(2): N450-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25604440

RESUMO

There is an increasing interest in recent years in using novel nanomaterials as cost-effective, sensitive, and reproducible substrate for surface-enhanced Raman spectroscopy (SERS) applications. In this study, a novel SERS substrate was developed by assembling gold nanorods into standing arrays on a gold-coated silicon slide. The standing nanorod arrays were closely packed on the gold film, generating strong electromagnetic field and uniformly distributed SERS "hot-spots" on the array surface. The as-prepared SERS substrates were used to detect a widely used pesticide (that is, carbaryl) in acetonitrile-water solution, apple juice, and cabbage. Results demonstrate that the actual concentrations of carbaryl in apple juice and cabbage were linearly correlated with the concentrations predicted by the multiple linear regression models (R > 0.97). The detection limits of carbaryl in apple juice and cabbage were both 2.5 ppm, meeting the maximum residue limits set by US Environmental Protection Agency (EPA). SERS can detect as low as 0.1 ppm of carbaryl in acetonitrile-water solution. In addition, satisfactory recoveries were obtained for carbaryl in both apple juice and cabbage. These results indicate that SERS coupled with the standing gold nanorod array substrates is a sensitive and reproducible method and can accurately detect pesticides in foods.


Assuntos
Bebidas/análise , Ouro/química , Nanopartículas Metálicas/química , Nanotubos/química , Praguicidas/análise , Verduras/química , Carbaril/análise , Malus/química , Nanoestruturas/química , Análise Espectral Raman/métodos
20.
Artigo em Inglês | MEDLINE | ID: mdl-25576945

RESUMO

A novel, sensitive, selective and simple kinetic spectrophotometric method has been developed for determination of trace levels of carbaryl based on its inhibitory effect on the oxidation of rhodamine-B by chlorine and bromine released from reaction of potassium bromate with hydrochloric acid in micellar medium. A linear relationship was observed between the inhibitory effect and the concentration of the compound. The absorbance was monitored at the maximum wavelength of 555 nm. The effect of different parameters such as pH, temperature and concentration of rhodamine-B, potassium bromate and surfactant on the reaction were investigated and optimum conditions were established. Under the selected experimental conditions, carbaryl was determined in the range of 0.04-0.4 µg mL(-1). Sandell's sensitivity and molar absorptivity were found to be 0.00055 µg cm(-2) and 3.658×10(5) L mol(-1) cm(-1) respectively. The proposed method was applied satisfactorily for the determination of carbaryl in water and different grain samples. The results were compared with those obtained by reference method and were found to be in agreement.


Assuntos
Carbaril/análise , Grão Comestível/química , Rodaminas/química , Espectrofotometria/métodos , Água/química , Bromatos/química , Calibragem , Corantes/química , Ácido Clorídrico/química , Cinética , Micelas , Oxirredução , Reprodutibilidade dos Testes , Temperatura
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