Environmentally friendly and novel solid-liquid phase microextraction of maneb fungicide in fruits and vegetables.

The dithiocarbamates class has been widely used in agriculture practices because of lower toxicity and instability than organophosphates and carbamates. Among them, the maneb has been used to produce several fruits and vegetables, but its high ingestion can adversely affect human health. This work developed the Solid-Liquid Phase Microextraction (SLPME) for extraction of the maneb in foods sample with posterior determination by Flow injection analysis-Flame Absorption Atomic Spectroscopy (FIA-FAAS). Curve analytical had a linear range from 0.9 to 20.0 µmol L-1 maneb (A = 5.94 × 10-4 C (µmol L-1) + 6.93 × 10-4), good repeatability (4.07%) and reproducibility (3.39%), limits of quantification (5.98 µmol L-1) and detection (0.197 µmol L-1), which was above of the established by regulatory agencies. The extraction of the maneb was performed using 685 µL of the solution of the 1.00 × 10-3 mol L-1 of EDTA, and it has excellent recovery values from 80.85 to 106.51%. Therefore, the developed SLPME demonstrated an alternative environmentally friendly for quickly extracting maneb from food samples (apple, papaya, and tomato).

A new strategy for the combination of supramolecular liquid phase microextraction and UV-Vis spectrophotometric determination for traces of maneb in food and water samples.

A novel and green method was developed for enrichment of maneb (manganese ethylene-bisdithiocarbamate) with a supramolecular solvent liquid phase microextraction method. The microextraction method has been used for the first time in the literature for separation-preconcentration of maneb. 1-decanol and tetrahydrofuran were used in the supramolecular solvent formation. The Mn2+ content of maneb was extracted in the supramolecular solvent phase as 1-(2-pyridylazo)-2-naphthol complex at pH 12.0. Manganese concentration was determined by UV-Vis spectrophotometer at 555 nm. Then, the maneb concentration equivalent to manganese concentration was calculated. The analytical parameters which effective in the method, including pH, volume of reagents, and sample volume were optimized. The limit of detection and the limit of quantification values for maneb were calculated as 2.22 µg L-1 and 7.32 µg L-1, respectively. The method was successfully applied in the analysis of the maneb content of water and food samples.

Stabilization of maneb group by ethylenediamine and direct-determination by liquid chromatography tandem mass spectrometry.

A rapid, low-cost, and selective method for simultaneous and direct determination of maneb group residues (containing ethylenebis and propylenebis dithiocarbamates) in fruit by liquid chromatography coupled to tandem mass spectrometry was developed and validated in the current study. The results showed the maneb group could be melt and stabilized by 5 v% ethylenediamine for 60 days keeping in conventional refrigerators, in which a stable and ionizable pentadentate ligand complex was considered to be formed by the bidentate diamine and sulfhydryl followed by Density Functional Theory calculation. The validated method showed a sensitive quantification limits (0.03 mg/kg), a steady recovery (82.1%-91.0%) and an excellent precision (2.7%-4.3% RSD). This method is applied to analyze fruit samples and achieved satisfactory results. Therefore, this method can be proposed as a robust analytical method of maneb group in fruit, and can be adapted to detect other compounds with sulfhydryl group.

The fungicide mancozeb affects soil invertebrates in two subtropical Brazilian soils.

Mancozeb is a dithiocarbamate non-systemic fungicide widely used to control fungal diseases of plants, commonly applied in apple orchards in Brazil. Instead of its common use, there are no reports about the risk to non-target organisms in Brazilian soils. We studied the risk of Mancozeb (in the commercial formulation Dithane® NT) for standard invertebrate species (Folsomia candida, Eisenia andrei and Enchytraeus crypticus) in two subtropical Brazilian soils, Oxisol and Ultisol, which are representative of apple production areas in Brazil. Reproduction and survival tests were carried out following ISO guidelines. Results showed that Mancozeb in Oxisol reduced the survival and reproduction of collembolans (LC50 54.43 and EC50 2.72 mg a.i. kg-1) and enchytraeids (LC50 6.97 and EC50 3.56 mg a.i. kg-1), in lowest values than those observed in Ultisol (F. candida LC50 > 1000 and EC50 > 100 mg a.i. kg-1; E. crypticus LC50 280.21 and EC50 29.67). Effects to E. andrei were similar in both soils and indicated a lower sensitivity of this species to Mancozeb. The species F. candida and E. crypticus were more sensitive than E. andrei. These results reinforce the need to include other soil organisms besides earthworms, using chronical endpoints and considering different types of soils, to better predict the risk of pesticides for subtropical soils.

Surface-Enhanced Raman Spectroscopy (SERS) of Mancozeb and Thiamethoxam Assisted by Gold and Silver Nanostructures Produced by Laser Techniques on Paper.

Advanced gold (Au) and silver (Ag) nanostructures were produced by laser techniques on printer paper substrate. Surface-enhanced Raman spectroscopy (SERS) analyses of the fungicide mancozeb (Dithane DG) and insecticide thiamethoxam (Aktara 25 BG) in quantities smaller than usually applied in agricultural medicine were performed for the first time assisted by the structures fabricated. The investigations and results show an easy alternative and cheap way to detect small amounts or residue of harmful environmental pollutants, which has a direct bearing on food quality and thus on human health.

Environmental and biological monitoring for the identification of main exposure determinants in vineyard mancozeb applicators.

Grapevine is a vulnerable crop to several fungal diseases often requiring the use of ethylenebisdithiocarbamate (EBDC) fungicides, such as mancozeb. This fungicide has been reported to have goitrogenic, endocrine disrupting, and possibly immunotoxic effects. The aim of this study was to assess workers' exposure in two scenarios of mancozeb application and analyse the main determinants of exposure in order to better understand their mechanism of influence. Environmental monitoring was performed using a modified Organisation for Economic Co-operation and Development (OECD) "patch" methodology and by hand-wash collection, while mancozeb's metabolite, ethylenethiourea (ETU), was measured in 24-h preexposure and postexposure urine samples. Liquid chromatography-mass spectrometry was used for determination of mancozeb and ETU in different kinds of samples. Closed tractor use resulted in 40 times lower potential exposure compared with open tractor. Coveralls reduced skin exposure 4 and 10 times in case of open and closed tractors, respectively. Gloves used during application resulted in 10 times lower hand exposure in open but increased exposure in closed tractors. This study has demonstrated that exposure to mancozeb is low if safe occupational hygiene procedures are adopted. ETU is confirmed as suitable biological marker of occupational exposure to mancozeb, but the absence of biological exposure limits significantly reduces the possibility to interpret biological monitoring results in occupationally exposed workers.

Determination of mancozeb residue in fruit by derivatization and a modified QuEChERS method using ultraperformance liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry method with derivatization and a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation was developed for the determination of mancozeb in fruits. The target compound was determined in less than 4.0 min with use of an electrospray ionization source in positive mode. The limits of detection and the limits of quantification ranged from 1.0 to 3.2 µg kg-1 and from 10 to 15 µg kg-1 in fruit respectively. The linearity was excellent for mancozeb (R 2 ≥ 0.9920). Recoveries in five matrices were obtained at three spiking levels (0.02, 0.1, and 1 mg kg-1). For all concentrations, the mean recoveries ranged from 84.0% to 95.9%, with repeatability relative standard deviation (n = 5) of 0.6 - 7.0%. The interday reproducibility relative standard deviation (n = 3) ranged from 1.4% to 5.5%. This method could be used for the routine detection of mancozeb residues in fruit. Graphical abstract The derivation of mancozeb and the detection process of derivative product by UPLC-MS/MS.

Manganese concentrations in drinking water from villages near banana plantations with aerial mancozeb spraying in Costa Rica: Results from the Infants' Environmental Health Study (ISA).

Elevated manganese (Mn) in drinking water has been reported worldwide. While, naturally occurring Mn in groundwater is generally the major source, anthropogenic contamination by Mn-containing fungicides such as mancozeb may also occur. The main objective of this study was to examine factors associated with Mn and ethylenethiourea (ETU), a degradation product of mancozeb, in drinking water samples from villages situated near banana plantations with aerial spraying of mancozeb. Drinking water samples (n = 126) were obtained from 124 homes of women participating in the Infants' Environmental Health Study (ISA, for its acronym in Spanish), living nearby large-scale banana plantations. Concentrations of Mn, iron (Fe), arsenic (As), lead (Pb), cadmium (Cd) and ethylenethiourea (ETU), a degradation product of mancozeb, were measured in water samples. Only six percent of samples had detectable ETU concentrations (limit of detection (LOD) = 0.15 µg/L), whereas 94% of the samples had detectable Mn (LOD = 0.05 µg/L). Mn concentrations were higher than 100 and 500 µg/L in 22% and 7% of the samples, respectively. Mn was highest in samples from private and banana farm wells. Distance from a banana plantation was inversely associated with Mn concentrations, with a 61.5% decrease (95% CI: -97.0, -26.0) in Mn concentrations for each km increase in distance. Mn concentrations in water transported with trucks from one village to another were almost 1000 times higher than Mn in water obtained from taps in houses supplied by the same well but not transported, indicating environmental Mn contamination. Elevated Mn in drinking water may be partly explained by aerial spraying of mancozeb; however, naturally occurring Mn in groundwater, and intensive agriculture may also contribute. Drinking water risk assessment for mancozeb should consider Mn as a health hazard. The findings of this study evidence the need for health-based World Health Organization (WHO) guidelines on Mn in drinking water.

Whirling agitated single drop microextraction technique for the simultaneous analysis of Paraquat and Maneb in tissue samples of treated mice.

A new microextraction technique, whirling agitated single drop microextraction, has been proposed for the simultaneous analysis of Paraquat and Maneb in tissue samples before liquid chromatography with tandem mass spectrometry. This technique is based on the idea that the escalatory motion of the sample solution along with the extraction solvent increases the movement of molecules into the extraction solvent. In this technique, a simple handheld rotator was utilized to rapidly agitate the biphasic extraction system for the instantaneous extraction of targeted analytes. After extraction, the extracted phase was directly solidified by cooling in crushed ice and easily collected using a micro-spatula. The method showed good performance by achieving sensitive detection limits at 4.81 ng g(-1) (Paraquat) and 9.12 ng g(-1) (Maneb). Mean recoveries and enrichment factors were obtained >91.21% and up to 114 that ensured the preconcentration capacity of the method. The method precision was verified by evaluating intraday variation (n = 10) ≤4.57 (Paraquat) and ≤4.68 (Maneb) in terms of percent relative standard deviation. Additionally, method efficacy was assured by obtaining very little matrix interferences (≤3.11%). Moreover, the method suitability was also checked with its application on tissue samples of intraperitoneally treated mice with Paraquat and Maneb.

Effects of washing, peeling, storage, and fermentation on residue contents of carbaryl and mancozeb in cucumbers grown in greenhouses.

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.

Degradation pattern and risk assessment of carbendazim and mancozeb in mango fruits.

A supervised field trial was conducted at four different agroclimatic locations in India to evaluate the dissipation pattern and risk assessment of carbendazim and mancozeb in mango fruits following foliar application of mixed formulation of carbendazim 12% and mancozeb 63% fungicide (SAAF-75WP) at recommended dose (90 + 472.5) and double the recommended dose (180 + 945 g a.i. ha(-1)). Average initial deposition of carbendazim was in the range of 1.12 to 2.7 and 1.95 to 4.09 mg kg(-1) and for mancozeb in the range of 2.25 to 2.71 and 4.17 to 5.96 mg kg(-1), given at respective doses. Residues of carbendazim and mancozeb were dissipated to the below detectable limit 7 days after spray at recommended dosage in all the locations. The fungicide degradation followed a first order kinetics with half-lives of 1-5 and 1-3 days, for carbendazim and mancozeb, respectively. The TMRC values, calculated from residue data generated from all four locations, were found to be below the MPI in mango fruit, and hence, the fungicide will not cause any adverse effect after consumption of mango fruits. This data could provide guidance for the proper and safe use of this fungicide mixture for managing disease incidence in mango in India.

Validation of a GC-MS method for the estimation of dithiocarbamate fungicide residues and safety evaluation of mancozeb in fruits and vegetables.

A sensitive and rugged residue analysis method was validated for the estimation of dithiocarbamate fungicides in a variety of fruit and vegetable matrices. The sample preparation method involved reaction of dithiocarbamates with Tin(II) chloride in aqueous HCl. The CS2 produced was absorbed into an isooctane layer and estimated by GC-MS selected ion monitoring. Limit of quantification (LOQ) was ⩽40µgkg(-1) for grape, green chilli, tomato, potato, brinjal, pineapple and chayote and the recoveries were within 75-104% (RSD<15% at LOQ). The method could be satisfactorily applied for analysis of real world samples. Dissipation of mancozeb, the most-used dithiocarbamate fungicide, in field followed first+first order kinetics with pre-harvest intervals of 2 and 4days in brinjal, 7 and 10days in grapes and 0day in chilli at single and double dose of agricultural applications. Cooking practices were effective for removal of mancozeb residues from vegetables.

Dynamics and residues of mixed formulation of fenamidone and mancozeb in gherkin field ecosystem.

The dynamics and residues of mixed formulation of fenamidone and mancozeb in a gherkin field ecosystem were investigated. The quantification was performed using gas chromatography-electron capture detection (GC-ECD) and UV-vis spectrophotometry for fenamidone and mancozeb residues, respectively. The method was validated using blank samples spiked at three levels and the results showed that recoveries ranged from 92 to 98 and 90 to 96 percent with relative standard deviations (RSD) ranging of 0.78-5.9 and 2.04-4.41 percent for fenamidone and mancozeb, respectively. The compound degradation followed a first order kinetics with half-lives of 2.8-2.82 and 2.02-2.26 days, for fenamidone and mancozeb, respectively. Pesticide residues in fruit were below the EU maximum residue level (MRL) after 10 days for fenamidone (0.02 µg/g) and just after treatment for mancozeb (2 µg/g). These results can be utilized in formulating the spray schedule and safety evaluation for these pesticides in gherkin.

Ability of NIRS technology to determine pesticides in liquid samples at maximum residue levels.

BACKGROUND: Pesticide residues remaining on food represent a potential risk to consumer's health. Determination of these pesticide residues involves tedious procedures of analysis with regard to time and laboratory work. Near-infrared spectroscopy (NIRS) is a possible alternative to these methods. The aim of this research was to evaluate the ability of NIRS to classify two pesticides used for controlling apple fruit pests according to their concentration. Different solutions were prepared, based on the dose recommended by the pesticide producers for apple pest treatments. Spectra were acquired on a spectrophotometer from liquid samples belonging to these solutions. RESULTS: Calibration models were developed from liquid samples, following the soft independent modelling of class analogy (SIMCA) analysis method. These models classified between 99 and 100% of the validation samples belonging to different pesticide concentration solutions even at the maximum residue limit level of these products in apple fruit. CONCLUSIONS: NIRS technology shows a high potential for identifying pesticides in liquid samples, according to their concentration, at the levels required by the legislation.

Persistence behaviour of fungicide mixture (benalaxyl-M 4% + mancozeb 65%) WP in grapes.

Benalaxyl-M [methyl N-phenylacetyl-N-2, 6-xylyl-DL-alaninate] is a newly introduced phenyl-amide fungicide whereas Mancozeb is one of the member of ethylenebisdiothiocarbamate (EBDC) fungicide. Benalaxyl-M in combination with Mancozeb effectively controls downy mildew of grapes. A two season field trial was conducted under West Bengal climatic condition during 2009-2010 to evaluate the dissipation pattern of fungicide mixture (Benalaxyl-M 4 % + Mancozeb 65 %) WP in grapes at two application rates (2,750 g and 5,500 g ha(-1)). The quantitative analysis was performed using liquid chromatography-mass spectrometry (LC-MS/MS) and UV-Vis spectrophotometer for Benalaxyl-M and Mancozeb residues respectively. Following the first order kinetics the fungicide Benalaxyl-M dissipates in grapes with half-life (T(1/2)) value ranges between 2.59 and 2.79 days irrespective of seasons and doses. The dissipation pattern of Mancozeb also follows first order kinetics with half-life (T(1/2)) value ranges between 3.86 and 4.93 days irrespective of seasons and doses.

Persistence of metalaxyl and mancozeb on potato leaves and their residues in tubers.

The persistence of fungicides on two commercial cultivars of potato was determined under field conditions at Punjab Agricultural University, Ludhiana, Punjab. Initial deposits of mancozeb on potato leaves were found to be 26.9 and 38.7 mg kg(-1), following application of ready mixture of fungicide metalaxyl 8% + mancozeb 64% (Ridomil MZ) at the rate of 1260 and 2520 g a.i. ha(-1), whereas metalaxyl residues were found to be 35.1 and 49.5 mg kg(-1), respectively. The residue level of mancozeb in potato leaves 15 days after application at single and double doze were 19.0 and 27.0 mg kg(-1) showing a loss of 29.6 and 30.3%, whereas the values for metalaxyl at single and double doze were 0.40 and 0.80 mg kg(-1) showing a loss of 98.9 and 98.4%, respectively. Residues of mancozeb and metalaxyl were not detected at 0.04 and 0.02 mg kg(-1) level in potato tubers at harvest (PHI = 53 days) at both the dosages, respectively. The persistence and dissipation of mancozeb with the application of Ridomil MZ followed similar trend as in Indofil M-45. The rate of fungicide dissipation increased with time after application in both the potato cultivars 'Kufri Chandramukhi' and 'Chipsona'. No significant difference was observed on initial deposit, persistence and dissipation of the two molecules between the two potato cultivars.

Residue dynamics of fenamidone and mancozeb on gherkin under two agro climatic zones in the state of Karnataka, India.

Residue dynamics of fenamidone and mancozeb on gherkin was evaluated at two different agro climatic zones i.e. at Bangalore (Zone-1) and Dharwad (Zone-2) in the state of Karnataka, India. Two treatments of the combination formulation (fenamidone 10% + mancozeb 50%) were given at the standard dose 150 + 750 g a.i. ha(-1) and double dose 300 + 1,500 g a.i. ha(-1). Initial residue deposits of fenamidone were 0.467 and 0.474 mg kg(-1) at Zone-1 and 2, respectively from standard dose treatment. From double dose treatment they were 0.964 and 0.856 mg kg(-1), respectively. Fenamidone residues persisted for 15 and 10 days and dissipated with the half-life of 4 and 3 days at Zone-1 and 2, respectively. Mancozeb residue deposits on gherkin were 0.383 and 0.428 mg kg(-1) from standard dose and 0.727 and 0.626 mg kg(-1) from double dose treatment at Zone-1 and 2, respectively. Mancozeb residues dissipated with the half-life of 2 and 1 day, respectively. Residues of both fenamidone and mancozeb dissipated faster at Zone-2 compared to Zone-1. The limit of quantification of fenamidone and mancozeb were 0.02 and 0.1 mg kg(-1), respectively in both gherkin and soil. Residues of fenamidone and mancozeb in soil collected on the 20th day from the 2 locations were found to be below quantifiable limit of both fungicides.

Kinetic and thermodynamic investigation of mancozeb degradation in tomato homogenate during thermal processing.

BACKGROUND: The kinetic and thermodynamic parameters of mancozeb degradation in tomato homogenates under the conditions prevailing in the manufacture of tomato products (at 60-100 °C for 0-60 min) were investigated. A gas chromatography-mass spectrometry method was used to analyse residual mancozeb in tomato homogenate. Ethylenethiourea (ETU), the main toxic degradation product of mancozeb, was measured by high-performance liquid chromatography (HPLC)-with photodiode array detector (PDA). RESULTS: The degradation of mancozeb and the formation of ETU in tomato homogenates were adequately described as first-order kinetics. Dependence of the rate constant followed the Arrhenius relationship. Apparent activation energies, temperature coefficients, half time and time to reduce to 90% of the initial value of mancozeb were calculated as kinetic parameters. The thermodynamic parameters of mancozeb were also described as Δg(d) = - 2.440 and 7.074 kJ mol⁻¹; Δh(d) = - 32.555 and - 42.767 kJ mol⁻¹; Δs(d) = - 0.090 and - 0.150 kJ mol⁻¹ K⁻¹; K(e) = 0.414 and 9.797 L g⁻¹ for 333 and 373 K respectively. CONCLUSION: Current findings may shed light on the reduction of mancozeb residue and its toxic degradation product during thermal processing of tomatoes and may also be valuable in awareness and prevention of potential risks from dietary exposure.

The effects of pesticide mixtures on degradation of pendimethalin in soils.

Most agronomic situations involve a sequence of herbicide, fungicide, and insecticide application. On the other hand, use of pesticidal combinations has become a standard practice in the production of many agricultural crops. One of the most important processes influencing the behavior of a pesticide in the environment is its degradation in soil. It is known that due to several pesticide applications in one vegetation season, the pesticide may be present in mixtures with other pesticides or xenobiotics in soil. This study examines the role which a mixture of chemicals plays in pesticide degradation. The influence of other pesticides on the rate of pendimethalin (PDM) degradation in soil was measured in controlled conditions. Mixtures of PDM with mancozeb or mancozeb and thiamethoxam significantly influenced the degradation of pendimethalin under controlled conditions. The second type of mixtures, with metribuzin or thiamethoxam, did not affect the behavior of pendimethalin in soil. Also, we determined the influence of water content on the rate of pendimethalin degradation alone in two soils and compared it to the rate in three pesticide mixtures. We compared two equations to evaluate the predictors of the rate of herbicide dissipation in soil: the first-order kinetic and the non-linear empirical models. We used the non-linear empirical model assuming that the degradation rate of a herbicide in soil is proportional to the difference of the observed concentration of herbicide in soil at time and concentration of herbicide in the last day of measurement.

Avoidance behaviour of Eisenia fetida to carbofuran, chlorpyrifos, mancozeb and metamidophos in natural soils from the highlands of Colombia.

Earthworm avoidance behaviour test is an important screening tool in soil eco-toxicology. This test has been developed and validated under North American and European conditions. However, little research has been performed on the avoidance test in the tropics. This work demonstrates the potential suitability of the avoidance behaviour test as screening method in the highlands of Colombia using Eisenia fetida as the bio-indicator species on contaminated soils with carbofuran and chlorpyrifos. Though for the two active ingredients 100% avoidance was not reached, a curve with six meaningful concentrations is provided. No significant avoidance behaviour trend was found for mancozeb and methamidophos. Tests were conducted in the field yielded similar results to the tests carried out in the laboratory for chlorpyrifos and mancozeb. However, for the case of carbofuran and methamidophos, differences of more than double in avoidance were obtained. Divergence might be explained by soil and temperature conditions.