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About a third of the world population is infected by helminth parasites implicated in foodborne trematodiasis. Fascioliasis is a worldwide disease caused by trematodes of the genus Fasciola spp. It generates huge economic losses to the agri-food industry and is currently considered an emerging zoonosis by the World Health Organization (WHO). The only available treatment relies on anthelmintic drugs, being triclabendazole (TCBZ) the drug of choice to control human infections. The emergence of TCBZ resistance in several countries and the lack of an effective vaccine to prevent infection highlights the need to develop new drugs to control this parasitosis. We have previously identified a group of benzochalcones as inhibitors of cathepsins, which have fasciolicidal activity in vitro and are potential new drugs for the control of fascioliasis. We selected the four most active compounds of this group to perform further preclinical studies. The compound's stability was determined against a liver microsomal enzyme fraction, obtaining half-lives of 34-169 min and low intrinsic clearance values (<13 µL/min/mg), as desirable for potential new drugs. None of the compounds were mutagenic or genotoxic and no in vitro cytotoxic effects were seen. Compounds C31 and C34 showed the highest selectivity index against liver fluke cathepsins when compared to human cathepsin L. They were selected for in vivo efficacy studies observing a protective effect, similar to TCBZ, in a mouse model of infection. Our findings strongly encourage us to continue the drug development pipeline for these molecules.

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The herbicide glyphosate (GLY) and its metabolite aminophosphonic acid (AMPA) are troublesome compounds for analysis in the environment. Here we report a reliable technique for GLY and AMPA determination in freshwater and soils by means of derivatization with 9-fluorenylmethoxycarbonyl chloride (FMOC-Cl) and further liquid chromatography with fluorescence detection (FLD) and tandem mass spectrometry (MS/MS) analysis. Selected experiments were carried out to evaluate selectivity, sensitivity, repeatability, linearity and quantification performance in both matrices.

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BACKGROUND: Fluazuron is a chitin synthesis inhibitor administered as a pour-on formulation in cattle for tick control. This study analyzes under endemic tick infestation, the incidence of the pour-on application pattern on the plasma levels of fluazuron in calves and cows in the lactation period of the beef cow. Two hundred and ninety-two beef cows around parturition were treated with a commercial pour-on formulation of fluazuron at a rate of 2.5 mg/kg of body weight. A total of 4 treatments were carried out on days 0, 32, 77, and 117. At each administration time, the cows were grouped according to the pour-on administration pattern: long (~ 60 cm pour-on application surface) and short (~ 30 cm pour-on application surface). Fluazuron levels in cows and calves plasma were determined before the third and fourth application for each subgroup (n = 10) by HPLC-MS/MS. During the entire study, cow-calf pairs were maintained under field conditions and qualitatively examined for tick infestation on the day of each treatment. Both treatments (long and short) schemes were designed to prevent the annual persistence of ticks. RESULTS: No animals with presence of ticks were identified during the first 117 days of the study, except for three cows and one calf at the time of the third application (day 77). There were no differences after 40 days (day 77) post-treatment of the second application (30 ± 5 ppb vs. 28.5 ± 12 ppb, p > 0.05) and 45 days (day 117) after the third application (147 ± 55 ppb vs 140 ± 46 ppb, p > 0.05) between groups of cows treated with the long or short pour-on application, respectively. Plasma concentration of fluazuron at second and third application was increased (3.3 and 2.9 times, respectively) in calves under free suckling compared to cows. Nevertheless, both groups of cows and calves showed a significant increase in plasma concentration of fluazuron between times (4.9 times, p < 0.0001 and 2.8 times, p < 0.0001, respectively). In both groups, tick prevalence was 0% throughout the trial, except for day 77, which reached 1%. CONCLUSIONS: The main conclusions of this study were the following: 1) Different administration patterns (long vs. short) did not differ in plasma levels of fluazuron.; 2) Given that only the cows were treated and lactating calves presented higher plasma levels of fluazuron than cows, passage through milk appears to be relevant and possibly due to a cumulative effect and continuous drug intake.

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Semiconductor nanoparticle-mediated photocatalysis is an attractive option for water decontamination, being the semiconductors as SnS2 with a bandgap in the visible region, the most promising materials. In the present work, we evaluated the influence of important parameters in the photocatalytic application of SnS2 nanoparticles. Our results show that the presence of citric acid (used as a capping agent) restricts the formation of hexagonal nanoparticles. We also demonstrated that using thioacetamide as a sulfur source results in smaller nanoparticles than thiourea, 24.0 nm and 616 nm respectively. Moreover, small hexagonal nanoparticles play a key role in the photocatalytic activity of SnS2 nanoparticles. Compared with TiO2 performance, SnS2 nanoparticles exhibited faster kinetics for methyl orange (MO) degradation, Kapp = 0.0102 min-1, and 0.029 min-1, respectively. We proved that SnS2 is capable of breaking the azo bond of methyl orange by direct reduction. Furthermore, our analyses indicate that SnS2 nanoparticles do not degrade atrazine and imazapic, but the photocatalytic route of metribuzin competed with photolysis, resulting in a particular transformation product that was not obtained with light irradiation only. We demonstrated that SnS2 nanoparticles have high bond selectivity for azo breaking. Furthermore, they represent an advance for the development of designed materials (such as heterostructures), where the properties of SnS2 can be tuned.

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With the aim of monitoring multiclass semi-polar pesticide residues in freshwater fatty fish, two QuEChERS approaches (so-called acetate buffered and unbuffered versions) were evaluated for the determination of 77 pesticide residues. Compounds were selected according to the dominant rainfed agriculture activities in South America. Unbuffered QuEChERS was finally chosen for validation purposes owing that it provided the best results in terms of recovery yields. Method performance was evaluated in two instrumental systems, liquid chromatography - tandem mass spectrometry (LC-MS/MS) in Scheduled MRM™ algorithm available on hybrid quadrupole - linear ion trap (QLIT) instrument, and gas chromatography - mass spectrometry (GC-MS) under selected ion monitoring (SIM) mode. Spiking experiments were carried out to determine the trueness, precision, linearity, limit of quantification of the method as well as matrix effect. The Unbuffered QuECHERS method described here: •Was validated for the analysis of 67 pesticide residues in fish muscle tissue.•Presented quantification limits in the range 1-15 µg kg-1 for the vast majority of the studied compounds.•Enable environmental monitoring of pesticide residues in fish due to their low LOQs.

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Environmental sustainability of South American rainfed agroecosystems is of current concern. In this work, we evaluate the occurrence of multiple pesticide residues in muscle tissue of wild fish species from two large rivers in South America (Uruguay and Negro Rivers). Two sampling campaigns (representing summer and winter crops) were performed during 2015 targeting a wide biodiversity of fish species used for human consumption (ranging from migratory to non-migratory and from detritivorous to top-predators). Three different localities associated to rainfed agriculture were assessed, two of them enclosed to a RAMSAR site (National Park "Esteros de Farrapos e Islas del Rio Uruguay"). Pesticide residues occurred in muscle tissue of 143 from 149 sampled fishes (96%). Thirty different pesticides were detected at concentrations from <1 to 194µgkg-1. Incidence of pesticides in fish were tightly related to: i) features of the contaminant: (Kow, environmental persistence and mobility) and ii) intensity of use of particular pesticides and land dedicated to rainfed agriculture. Trifloxystrobin, metolachlor and pyraclostrobin showed the highest rates of occurrence. Of great concern is that strobirulins have highest toxicity to fish from those detected compounds. From the pattern of pesticides occurring for non-migratory fish species it was possible to trend important spatial differences related to the intensity of rainfed agriculture. Results suggest a regular exposition of aquatic wild biota to sublethal concentrations of multiple semi-polar pesticides.

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The beehive as a quantitative monitor of pesticide residues applied over a soybean crop was studied through a semi field experiment of controlled exposure of honey bees to pesticides in macro tunnels. The distribution within exposed beehives of pesticides commonly used in soybean plantation, was assessed. Residue levels of insecticides in soybean leaves, honey bees, wax, honey and pollen were analyzed. The transference from pesticides present in the environment into the beehive was evidenced. The obtained results allow relating pesticide concentrations present in the environment with traces found in foraging bees. Therefore, pesticide transference ratios could be calculated for each detected compound (acetamiprid, imidacloprid and thiamethoxam) which showed a linear inverse trend with their 1-octanol/water partition coefficient (Kow). The least transferred pesticide to the hive (acetamiprid) has the highest vapor pressure (Vp). This study gives new insights on the usefulness of monitoring the environment through beehives aiming to evaluate if agroecosystems remain sustainable. It also contributes to generate valuable information for model building aiming to predict environmental quality through beehive's analysis.

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Abstract Microwave Assisted Extraction and a modified CEN-QuEChERS methodology were evaluated as extraction and clean up procedures for the simultaneous analysis of 42 organophosphate pesticides in yerba mate (Ilex paraguaiensis). The obtained extracts were analyzed by gas chromatography using a flame photometric detector. Linearity, recovery percentages, relative standard deviations, detection and quantification limits and matrix effects were determined according to DG-SANCO guidelines for both methods. At 0.2 and 0.5 mg/kg the evaluated methods showed percentages recoveries between 70 and 120% for most of the analytes. Using Microwave Assisted Extraction methodology, 33 pesticide residues could be properly analyzed whereas only 27 could be determined with the proposed modified QuEChERS. All relative standard deviation were below 18% except for omethoate and disulfoton sulfone when evaluated by the modified QuEChERS. The limits of detection in both methodologies were 0.2 mg/kg for most of the analyzed compounds. The average detection limit for QuEChERS was 0.04 mg/kg. For 19 of the analytes determined through Microwave Assisted Extraction the lowest validated level were 0.004 mg/kg. Signal suppression/enhancement was observed for most of the pesticides, thus matrix-matched calibration curves were used for quantification. The Microwave Assisted Extraction and QuEChERS procedures studied could detect the organophosphate pesticides above the MRL fixed for "mate" by the European Union. They have been successfully applied for the determination of organophosphate pesticide residues in commercial samples and the positives were confirmed through GC–(ITD)-MS.

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The results of an experiment to study the occurrence and distribution of pesticide residues during rice cropping and processing are reported. Four herbicides, nine fungicides, and two insecticides (azoxystrobin, byspiribac-sodium, carbendazim, clomazone, difenoconazole, epoxiconazole, isoprothiolane, kresoxim-methyl, propanil, quinclorac, tebuconazole, thiamethoxam, tricyclazole, trifloxystrobin, λ-cyhalotrin) were applied to an isolated rice-crop plot under controlled conditions, during the 2009-2010 cropping season in Uruguay. Paddy rice was harvested and industrially processed to brown rice, white rice, and rice bran, which were analyzed for pesticide residues using the original QuEChERS methodology and its citrate variation by LC-MS/MS and GC-MS. The distribution of pesticide residues was uneven among the different matrices. Ten different pesticide residues were found in paddy rice, seven in brown rice, and eight in rice bran. The highest concentrations were detected in paddy rice. These results provide information regarding the fate of pesticides in the rice food chain and its safety for consumers.

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The influence of insecticides commonly used for agricultural purposes on beehive depopulation in Uruguay was investigated. Honeycombs, bees, honey and propolis from depopulated hives were analyzed for pesticide residues, whereas from active beehives only honey and propolis were evaluated. A total of 37 samples were analyzed, representing 14,800 beehives. In depopulated beehives only imidacloprid and fipronil were detected and in active beehives endosulfan, coumaphos, cypermethrin, ethion and chlorpyrifos were found. Coumaphos was present in the highest concentrations, around 1,000 µg/kg, in all the propolis samples from active beehives. Regarding depopulated beehives, the mean levels of imidacloprid found in honeycomb (377 µg/kg, Standard Deviation: 118) and propolis (60 µg/kg, Standard Deviation: 57) are higher than those described to produce bee disorientation and fipronil levels detected in bees (150 and 170 µg/kg) are toxic per se. The other insecticides found can affect the global fitness of the bees causing weakness and a decrease in their overall productivity. These preliminary results suggest that bees exposed to pesticides or its residues can lead them in different ways to the beehive.

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A multiresidue method was developed for the quantification and confirmation of 70 pesticides in paddy field water. After its filtration, water was injected directly in a liquid chromatograph coupled to a hybrid triple quadrupole-linear ion trap-mass spectrometer (QqLIT). The list of target analytes included organophosphates, phenylureas, sulfonylureas, carbamates, conazoles, imidazolinones and others compounds widely used in different countries where rice is cropped. Detection and quantification limits achieved were in the range from 0.4 to 80 ng L(-1) and from 2 to 150 ng L(-1), respectively. Correlation coefficients for the calibration curves in the range 0.1-50 µg L(-1) were higher than 0.99 except for diazinon (0.1-25 µg L(-1)). Only 9 pesticides presented more than 20% of signal suppression/enhancement, no matrix effect was observed in the studied conditions for the rest of the target pesticides. The method developed was used to investigate the occurrence of pesticides in 59 water samples collected in paddy fields located in Spain and Uruguay. The study shows the presence of bensulfuron methyl, tricyclazole, carbendazim, imidacloprid, tebuconazole and quinclorac in a concentration range from 0.08 to 7.20 µg L(-1).

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A validated analytical method for the multiresidue analysis of 40 organophosphate pesticides (OPs) and conversion products in raw wool has been developed. The method is based on the selective microwave-assisted extraction (MAE) of raw wool with acetonitrile and analysis of extracts by gas chromatography-flame photometric detector. The optimum MAE conditions were 20 min duration at 80 °C with 30 mL of acetonitrile per gram of wool. A validation study was performed according to the European SANCO guidelines 10684/2009. Limits of detection and quantification for all pesticides tested were from 0.01 to 0.2 mg/kg and from 0.2 to 1.0 mg/kg, respectively. The average recoveries of pesticides spiked at different levels were in the range of 70-120% with relative standard deviations of ≤ 20%. The extraction performance was compared to the one obtained with a reference Soxhlet extraction. The method was also applied in the analysis of real wool (after field application) samples.

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In order to evaluate the extraction of pesticide residues that are transferred to the brew during mate drinking process of P.U.1 yerba mate leaves (Ilex paraguariensis), a special device to simulate the way in which mate is drunk in Uruguay was developed. The transfer to the brew of 12 organophosphates, 5 synthethic pyrethroids and one organochlorine pesticide from spiked samples was studied. The relationship between the transfer data thus obtained and physicochemical properties like water solubility (Ws), octanol-water coefficient (Kow) and Henry's constant (H) was evaluated. The extractability of the pesticide residues from yerba mate can be correlated with log Ws and log Kow. These transfer values allowed the calculation of ARLs (acceptable residue level) for the pesticides following Food and Agriculture Organization (FAO), World Health Organizaion (WHO) guidelines. These results can help the future establishment of maximum residue levels (MRLs).

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A sensitive, rapid, and simple multiresidue method for the simultaneous determination of six postemergence herbicides currently used in rice cultivation--metsulfuron methyl, bensulfuron methyl, pyrazosulfuron ethyl, bentazone, bispyribac sodium, and cyhalofop butyl--in drinking and paddy-field water is presented. Water samples were extracted with solid-phase extraction cartridges. Final determination was made by LC with diode-array detection. The extraction efficiencies of C18 and HLB cartridges were compared. The average recovery obtained for these compounds for the lowest spiked level (0.1 microg/L) varied from 70 to 122% for C18 and 75-119% for HLB, with RSDs of 11 and 8.3%, respectively. The method had good linearity, and the lower detection limit for the pesticides studied varied from 0.03 to 0.04 microg/L. The proposed method was also tested in paddy-field water, with recovery studies giving good results with low RSDs at 1.0 microg/L.

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