Multicompartmental monitoring of legacy and currently used pesticides in a subtropical lake used as a drinking water source (Laguna del Cisne, Uruguay).

A pilot annual monitoring survey (April 2018-March 2019) was conducted to investigate the presence of pesticides in superficial water and fish in Laguna del Cisne, one of the most critical drinking water sources in Uruguay. A total of 25 pesticide residues were detected in superficial water (89.3 % of the samples). Pesticide's temporal distribution was associated with crops and livestock practices, with higher occurrences in spring and summer than in autumn and winter. The most frequent compounds in superficial water were the insecticide chlorantraniliprole, and the herbicides glyphosate (including its metabolite AMPA) and metolachlor. The levels of Organochlorine pesticide, p,p'-DDT, was in some cases two order of magnitude above the international water quality guidelines for Ambient Water Criteria. In fishes, eight different pesticides were detected, at concentrations from 1000 to 453,000 ng·kg-1. The most frequent pesticides found were propiconazole, chlorpyrifos, and p,p'-DDE. The widespread occurrence of pesticides in fish suggests potential exposure effects on fish populations and the aquatic ecosystem. The sampling approach of this work allowed monitoring the continuous concentrations of several pesticides in surface waters and fishes to establish the influence from past and current agriculture practices in Laguna del Cisne basin. For safety measures, continuous monitoring programs must be performed in this system to prevent toxicity impacts on aquatic organisms and human health.

Influence of Cultivar on Nutritional Composition and Nutraceutical Potential of Pecan Growing in Uruguay.

Composition and antioxidant properties of sixteen pecan [Carya illinoinensis (Wangenh) K. Koch] cultivars grown simultaneously in a single experimental orchard in Uruguay were evaluated to characterize their nutritional properties and nutraceutical potential. The percentage of oil, moisture, ash, minerals, and proteins were determined and also the fatty acid profile. Total phenolic compounds [18-41 mg gallic acid equivalents (GAEs)/g], condensed tannin [2-12 mg catechin equivalents (CEs)/g], and tocopherols (110-163 µg/g) contents were estimated in nut kernels. Total phenolic compounds (32-117 mg GAE/g), condensed tannins (130-357 mg CE/g), and total anthocyanins (1-3 mg 3-glucoside cyanidin/g) were also determined for pecan shells. The antioxidant activity in shells [57.15-578.88 µmol Trolox equivalents (TEs)/g] was 5 times higher compared with the kernels (23.15-156.60 µmol TEs/g) measured with hydrophilic ORAC. Bioactive compounds concentrations present statistically significant genetic variability between cultivars studied (p < 0.05). The presence of phenolic compounds was related with high-antioxidant capacity in kernels and shells, and a strong correlation between content of total phenolic compounds and condensed tannins in pecan shells was found. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) show association between cultivars and the observed variables. The nutritional profile in the different cultivars showed the trends described in other countries, but this work shows some significant differences that could be attributed to the specific edaphoclimatic conditions of cultivation in Uruguay.

Multiresidue analysis of basic, neutral, and acidic pesticides in biobeds' biomixture.

Contain between 1 and 3 bullet points highlighting the customization rather than the steps of the procedure. An analytical methodology was adjusted and validated for the analysis of 15 selected pesticides currently employed in extensive agriculture. The main application of this methodology is studying the pesticides degradation behavior using biobeds as a friendly environmental tool for the treatment of wastewaters generated in fields. The scope of the method was selected based on the most used pesticides in soybean crops in Uruguay. The novelty of this work is the inclusion of neutral and acidic herbicides such as 2,4-D, clethodim, dicamba, together with fungicides and insecticides which are usually included in Multi Residue Methods. An acetonitrile extraction methodology without a clean-up step yielded acceptable results for all the analytes. The instrumental analysis was performed using HPLC-MS/MS. The selected methodology was validated according to the SANTE guidelines. The recoveries were between 65 and 130% with RSD < 20%. The instrumental LOQs were fixed at 1 µg/L for all the compounds except for clethodim, and the method LOQs were 1 mg/kg in biomixture dry basis. These LOQs values are acceptable for biodegradation studies in biobeds. A multiresidue methodology was: • Validated for 15 pesticides in biomixture. • Acidic herbicides were included in the scope. • The method was employed for the environmental monitoring of pesticide degradation in biobeds.

Antioxidant, Antidiabetic, and Antiobesity Properties, TC7-Cell Cytotoxicity and Uptake of Achyrocline satureioides (Marcela) Conventional and High Pressure-Assisted Extracts.

The growing incidence of non-communicable diseases makes the search for natural sources of bioactive compounds a priority for such disease prevention/control. Achyrocline satureioides ('marcela'), a plant rich in polyphenols and native to Brazil, Uruguay, Paraguay, and Argentina, could be used for this purpose. Data on its antidiabetic/antiobesity properties and cellular uptake of bioactive compounds are lacking. The potentiality of non-thermal technologies such as high-hydrostatic pressure (HP) to enhance polyphenol extraction retains attention. Thus, in the present study aqueous and ethanolic marcela extracts with/without assisted-HP processing were chemically characterized and assessed for their in vitro antioxidant capacity, antidiabetic and antiobesity activities, as well as cellular cytotoxicity and uptake on intestinal cell monolayers (TC7-cells, a clone of Caco-2 cells). Aqueous and ethanolic conventional extracts presented different polyphenolic profiles characterized mainly by phenolic acids or flavonoids, respectively, as stated by reverse phase-high-performance liquid chromatography (RP-HPLC) analyses. In general, ethanolic extracts presented the strongest bioactive properties and HP had none or a negative effect on in vitro bioactivities comparing to conventional extracts. TC7-cell viability and cellular uptake demonstrated in conventional and HP-assisted extracts, highlighted the biological effects of marcela bioactive compounds on TC7-cell monolayers. TC7-cell studies showed no HP-induced cytotoxicity. In sum, marcela extracts have great potential as functional ingredients for the prevention/treatment of chronic diseases such as diabetes.

GC-MS and LC-MS/MS workflows for the identification and quantitation of pyrrolizidine alkaloids in plant extracts, a case study: Echium plantagineum

Abstract Workflows based on gas and liquid chromatography coupled to mass spectrometry for the identification of toxic pyrrolizidine alkaloids present in plants were developed and applied to Echium plantagineum L., Boraginaceae, extracts. GC-MS based determinations need reduction and derivatization steps prior to MS analysis, which is performed using a Full Scan and Single Ion Monitoring sequence for screening, identification and quantification purposes. The LC-(ESI)-MS/MS determination was performed directly from the extract without derivatization. Acetyl lycopsamine, echimidine, echimidine N-oxide, echiumine, echiumine N-oxide, lycopsamine, lycopsamine N-oxide, 7,9-ditigloylretronecine N-oxide and a not reported PA of m/z 466, were identified and quantified in E. plantagineum extracts, through three operating modes of LC-QTRAP: precursor ion scan, enhanced product ion scan and multiple reaction monitoring. Precursor ion scan detects all the ions that give rise to a daughter ion at m/z 120, the presence of the parent pyrrolizidine alkaloid is confirmed through its MS2 spectrum (enhanced product ion) and quantified by multiple reaction monitoring. These workflows are general approaches to study chemical families using GC/LC-MS. For extracts suspicious of containing pyrrolizidine alkaloids, they are suitable tools for the quality and safety control of food, feed as well as phytotherapeutics.

Determination of multiclass, semi-polar pesticide residues in fatty fish muscle tissue by gas and liquid chromatography mass spectrometry.

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.

Validation of an Analytical Method for the Determination of Pesticide Residues in Vine Leaves by GC-MS/MS.

A modified and miniaturized SweEt/QuEChERS method for pesticide residue analysis applied to vine leaves is presented. The deep-frozen plant material was cryogenically processed. A 2 g analytical portion was hydrated for 30 min and extracted with acidified ethyl acetate after buffering with NaHCO3 and adding Na2SO4. A dispersive solid-phase (d-SPE) cleanup step with primary-secondary amine (PSA) was performed. The pesticide residues were determined using GC-MS/MS. The whole procedure was validated for 54-59 pesticides at 0.01, 0.02, 0.1, and 0.2 mg/kg in fresh vine leaves ( Vitis vinifera). The key method performance parameters investigated were specificity, linearity, trueness, within laboratory repeatability and reproducibility, limit of detection, limit of quantitation, and matrix effects. Recoveries for the 59 pesticides tested ranged from 60 to 110%, and the RSDs were lower than 20% for the majority of the pesticides studied.

Phenolic Profiling and Antioxidant Capacity of Eugenia uniflora L. (Pitanga) Samples Collected in Different Uruguayan Locations.

The use of nutrient-rich foods to enhance the wellness, health and lifestyle habits of consumers is globally encouraged. Native fruits are of great interest as they are grown and consumed locally and take part of the ethnobotanic knowledge of the population. Pitanga is an example of a native fruit from Uruguay, consumed as a jelly or an alcoholic beverage. Pitanga has a red-violet pigmentation, which is a common trait for foods that are a good source of antioxidants. Hence, fruits from different Uruguayan regions were analyzed via miniaturized sample preparation method, HPLC-DAD-ESI/MSn and RP-HPLC-DAD techniques to identify and quantify phenolic compounds, respectively. The antioxidant capacity was evaluated via DPPH and ORAC (Oxygen Radical Absorbance Capacity) assays. A multivariate linear regression was applied to correlate the observed antioxidant capacity with the phenolic content. Furthermore, Principal Components Analysis was performed to highlight characteristics between the various samples studied. The main results indicated differences between northern and southern Uruguayan samples. Delphinidin-3-hexoside was present in southern samples (mean of 293.16 µmol/100 g dry weight (DW)) and absent in the sample collected in the north (sample 3). All the samples contain high levels of cyanidin-3-hexoside, but a noticeable difference was found between the northern sample (150.45 µmol/100 g DW) and the southern sample (1121.98 µmol/100 g DW). The antioxidant capacity (mean ORAC of 56370 µmol Trolox®/100 g DW) were high in all the samples compared to the Food and Drug Administration (FDA) database of similar berry-fruits. The results of this study highlight the nutraceutical value of a native fruit that has not been exploited until now.

Miniaturized QuEChERS based methodology for multiresidue determination of pesticides in odonate nymphs as ecosystem biomonitors.

The impacts of the modern, agrochemicals based agriculture that threatens the overall systems sustainability, need to be monitored and evaluated. Seeking for agroecosystems monitors, the present article focus in the occurrence and abundance of aquatic macroinvertebrates, that have been frequently used as bioindicators of water quality due to their relationship with land use. Some of these organisms are on the top of the food chain, where bioaccumulation and biomagnification processes can be observed, and they can turn into secondary pollution sources of systems and terrestrial organisms as well. Odonate nymphs, which belong to the functional group of predators, were selected for this study. A methodology to determine 73 pesticide residues in odonate nymphs by LC-MS/MS and GC-MS/MS was developed. A QuEChERS sample preparation strategy was adapted. As it is complex to obtain samples especially in disturbed ecosystems, the method was minimized to a sample size of 200mg of fresh nymphs. The method was validated and good recoveries (71-120%) with RSDs below 20% for the majority of the studied pesticides at least at two of the assayed levels 1, 10 and 50µgkg-1 were obtained. For 32 analytes the limit of quantitation was 1µgkg-1 and 10µgkg-1 for the others. The lineal range was observed between 1-100µgkg-1 in matrix-matched and solvent calibration curves for most of the assessed pesticides. LC-MS/MS matrix effects were evaluated, 40% of the analytes presented low or no signal suppression. Only flufenoxuron presented high matrix effects. The obtained methodology is adequate for pesticide multiresidue analysis in aquatic macroinvertebrates (odonates) aiming to contribute to the ecological state evaluation of freshwater ecosystems.

Antimutagenic and antioxidant properties of the aqueous extracts of organic and conventional grapevine Vitis labrusca cv. Isabella leaves in V79 cells.

Grapes are one of the most commonly consumed fruit, in both fresh and processed forms; however, a significant amount is disposed of in the environment. Searching for a use of this waste, the antigenotoxic, antimutagenic, and antioxidant activities of aqueous extracts from organic and conventional Vitis labrusca leaves were determined using V79 cells as model. The antigenotoxic activity was analyzed by the alkaline comet assay using endonuclease III and formamidopyrimidine DNA glycosylase enzymes. The antimutagenic property was assessed through the micronucleus (MN) formation, and antioxidant activities were assessed using 2',7'-dichlorodihydrofluorescin diacetate (DCFH-DA) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH(●)) radical scavenging, as well as with superoxide dismutase (SOD) and catalase (CAT) activity assays. In addition, phenolic content and ascorbic acid levels of both extracts were determined. Data showed that both organic and conventional grapevine leaves extracts possessed antigenotoxic and antimutagenic properties. The extract of organic leaves significantly reduced intracellular reactive oxygen species (ROS) levels in V79 cells, and displayed greater ability for DPPH(●) scavenging and higher SOD and CAT activities than extract from conventional leaves. Further, the extract from organic leaves contained higher phenolic and ascorbic acid concentrations. In summary, extracts from organic and conventional grape leaves induced important in vitro biological effects.

Comparison and evaluation of two methods for the pesticide residue analysis of organophosphates in yerba mate

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.

Negative chemical ionization gas chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry and automated accurate mass data processing for determination of pesticides in fruit and vegetables.

Gas chromatography coupled to high resolution hybrid quadrupole time-of-flight mass spectrometry (GC-QTOF MS), operating in negative chemical ionization (NCI) mode and combining full scan with MSMS experiments using accurate mass analysis, has been explored for the automated determination of pesticide residues in fruit and vegetables. Seventy compounds were included in this approach where 50 % of them are not approved by the EU legislation. A global 76 % of the analytes could be identified at 1 µg kg(-1). Recovery studies were developed at three concentration levels (1, 5, and 10 µg kg(-1)). Seventy-seven percent of the detected pesticides at the lowest level yielded recoveries within the 70 %-120 % range, whereas 94 % could be quantified at 5 µg kg(-1), and the 100 % were determined at 10 µg kg(-1). Good repeatability, expressed as relative standard deviation (RSD <20 %), was obtained for all compounds. The main drawback of the method was the limited dynamic range that was observed for some analytes that can be overcome either diluting the sample or lowering the injection volume. A home-made database was developed and applied to an automatic accurate mass data processing. Measured mass accuracies of the generated ions were mainly less than 5 ppm for at least one diagnostic ion. When only one ion was obtained in the single-stage NCI-MS, a representative product ion from MSMS experiments was used as identification criterion. A total of 30 real samples were analyzed and 67 % of the samples were positive for 12 different pesticides in the range 1.0-1321.3 µg kg(-1).

QuEChERS-based method for the multiresidue analysis of pesticides in beeswax by LC-MS/MS and GC×GC-TOF.

The validation of an analytical procedure for the determination of pesticide residues in beeswax, an interesting matrix for environmental pollution monitoring, is presented. Using the QuEChERS template, the impacts of wax particle size, sample amount, and cleanup procedure (water addition, dispersive solid phase extraction, freeze-out, and combinations thereof) on extraction yield and coextractive load were studied. Sample preparation through liquid-liquid partitioning between acetonitrile and melted wax (∼80 °C), followed by freeze-out and primary-secondary amine dispersive cleanup, was performed on incurred and pesticide-free samples for 51 residues. Determinations were made through LC-MS/MS and GC×GC-TOF, and the whole procedure was validated. Matrix effects were evaluated, with recoveries between 70 and 120% and RSDs below 20% in almost all cases. LC-MS/MS LOQs ranged from 0.01 to 0.1 mg/kg for most pesticides, but for GC-amenable pesticides, GC×GC-TOF sensitivity was lower (0.1-0.2 mg/kg). This methodology can be applied for routine analysis of pesticide residues in beeswax.

Anticonvulsant, neuroprotective and behavioral effects of organic and conventional yerba mate (Ilex paraguariensis St. Hil.) on pentylenetetrazol-induced seizures in Wistar rats.

Epilepsy, which is one of the most common neurological disorders, involves the occurrence of spontaneous and recurrent seizures that alter the performance of the brain and affect several sensory and behavioral functions. Oxidative damage has been associated with post-seizure neuronal injury, thereby increasing an individual's susceptibility to the occurrence of neurodegenerative disorders. The present study investigated the possible anticonvulsive and neuroprotective effects of organic and conventional yerba mate (Ilex paraguariensis), a plant rich in polyphenols, on pentylenetetrazol (PTZ)-induced seizures in Wistar rats. The behavioral and polyphenolic profiles of the yerba mate samples were also evaluated. Infusions of yerba mate (50mg/kg) or distilled water were given to rats for fifteen days by oral gavage. On the 15th day the animals were subjected to open field test, and exploratory behavior was assessed. Subsequently, 60mg/kg PTZ (i.p.) was administered, and animals were observed for the appearance of convulsions for 30min. Latency for the first seizure, tonic-clonic and generalized seizures time, frequency of seizures and mortality induced by PTZ were recorded. The animals were then sacrificed, and the cerebellum, cerebral cortex and hippocampus were quickly removed and frozen to study the neuroprotective effects of yerba mate. The oxidative damage in lipids and proteins, nitric oxide levels, the activities of the antioxidant enzymes superoxide dismutase (Sod) and catalase (Cat) and non-enzymatic cellular defense (sulfhydryl protein) were quantified in all the tissues. The results showed that organic and conventional yerba mate infusions were able to reduce the frequency of seizures when compared to the PTZ group. Besides, organic yerba mate infusion decreases the tonic-clonic seizures time in relation to the PTZ group. It was also shown that organic and conventional yerba mate infusions reduced the oxidative damage in lipids and proteins and nitric oxide levels and prevented the decrease in Sod and Cat activities and sulfhydryl protein content when compared to the PTZ group in all the CNS tissues assayed. Organic and conventional yerba mate commercial samples did not change the behavior (locomotion, exploration or anxiety) of the treated animals. In both organic and conventional infusions, the presence of the polyphenols rutin, chlorogenic acid and their acyl derivatives were detected, which could be associated with the biological effects observed. These data indicate that yerba mate may provide new perspectives for the development of therapeutic approaches with natural compounds in the pharmaceutical area, both to reduce the convulsions' frequency and to minimize the neuronal damage associated with recurrent seizures.

Organic and Conventional Yerba Mate (Ilex paraguariensis A. St. Hil) Improves Metabolic Redox Status of Liver and Serum in Wistar Rats.

Organic and conventional yerba mate (Ilex paraguariensis) is widely used in South America to prepare nonalcoholic drinks rich in polyphenols. These compounds are able to prevent the generation of reactive species, thus minimizing the incidence of several diseases. In this perspective, we hypothesized that yerba mate may have protective effects against pentylenetetrazol (PTZ)-induced oxidative damage in liver and serum of rats. Animals (n = 42) received distilled water (control) or yerba mate (organic or conventional) for fifteen days. Then, half of the rats of each group received 60 mg/kg PTZ intraperitoneally or saline solution. After 30 min the animals were euthanized and the liver and blood were collected. The results showed that organic and conventional yerba mate avoided PTZ-induced oxidative damage and nitric oxide production in the liver and serum of the rats. Moreover, both kinds of yerba mate prevented the decrease in enzymatic (superoxide dismutase and catalase) and non-enzymatic (sulfhydryl protein content) defenses in the liver and serum. In addition, histopathologic analysis of the liver showed that yerba mate reduced PTZ-induced cell damage. These findings indicate that yerba mate provides hepatoprotection and improves antioxidant status in the serum, which may contribute to the development of new therapeutic strategies using nutraceuticals drinks.

Analytical methodology for the study of endosulfan bioremediation under controlled conditions with white rot fungi.

A general procedure to study the biodegradation of endosulfan under laboratory conditions by white rot fungi isolated from native sources growing in YNB (yeast nitrogen base) media with 1% of glucose is presented. The evaluation of endosulfan biodegradation as well as endosulfan sulfate, endosulfan ether and endosulfan alcohol production throughout the whole bioremedation process was performed using an original and straightforward validated analytical procedure with recoveries between 78 and 112% at all concentration levels studied except for endosulfan sulfate at 50 mg L(-1) that yielded 128% and RSDs<20%. Under the developed conditions, the basidiomycete Bjerkandera adusta was able to degrade 83% of (alpha+beta) endosulfan after 27 days, 6 mg kg(-1) of endosulfan diol were determined; endosulfan ether and endosulfan sulfate were produced below 1 mg kg(-1) (LOQ, limit of quantitation).

Cytotoxic, virucidal, and antiviral activity of South American plant and algae extracts.

Herpes simplex virus type 1 (HSV-1) infection has a prevalence of 70% in the human population. Treatment is based on acyclovir, valacyclovir, and foscarnet, three drugs that share the same mechanism of action and of which resistant strains have been isolated from patients. In this aspect, innovative drug therapies are required. Natural products offer unlimited opportunities for the discovery of antiviral compounds. In this study, 28 extracts corresponding to 24 plant species and 4 alga species were assayed in vitro to detect antiviral activity against HSV-1. Six of the methanolic extracts inactivated viral particles by direct interaction and 14 presented antiviral activity when incubated with cells already infected. Most interesting antiviral activity values obtained are those of Limonium brasiliense, Psidium guajava, and Phyllanthus niruri, which inhibit HSV-1 replication in vitro with 50% effective concentration (EC(50)) values of 185, 118, and 60 µg/mL, respectively. For these extracts toxicity values were calculated and therefore selectivity indexes (SI) obtained. Further characterization of the bioactive components of antiviral plants will pave the way for the discovery of new compounds against HSV-1.

Occurrence and distribution study of residues from pesticides applied under controlled conditions in the field during rice processing.

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.

Detection of pesticides in active and depopulated beehives in Uruguay.

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.

Determination of coumaphos, chlorpyrifos and ethion residues in propolis tinctures by matrix solid-phase dispersion and gas chromatography coupled to flame photometric and mass spectrometric detection.

A new analytical method has been developed and successfully evaluated in routine application for the quantitative analysis of a selected group of organophosphate pesticides (coumaphos, chlorpyrifos and ethion) which can be found at trace levels in propolis tinctures (ethanolic propolis extracts); a valuable commodity used as raw material in the food and pharmaceutical industries for which there have been few attempts for pesticide residue analysis reported in the literature. The proposed methodology is based on matrix solid phase dispersion (MSPD) using aluminum sulfate anh. a novel dispersant material and subsequent column chromatography clean-up in silica gel prior to gas chromatography (GC) with both flame photometric detector (FPD) and mass spectrometry (MS) detection used for the routine quantification and identification of the residues, respectively. The limits of detection, for coumaphos, chlorpyrifos and ethion were below 26.0 µg/kg in FPD and 1.43 µg/kg for MS detection. Mean recoveries were in the range of 85-123% with RSD values below 13%, which suggests that the proposed method is fit for the purpose of analyzing pesticides in propolis tinctures containing high concentration of polyphenolics. The method has been successfully applied in our laboratory for the last 2 year in the analysis of real propolis tinctures samples.