Natalia Besil

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.

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.

Matrix Effects and Interferences of Different Citrus Fruit Coextractives in Pesticide Residue Analysis Using Ultrahigh-Performance Liquid Chromatography–High-Resolution Mass Spectrometry

The matrix effects of ethyl acetate extracts from seven different citrus fruits on the determination of 80 pesticide residues using liquid chromatography coupled to high-resolution time-of-flight mass spectrometry (UHPLC-(ESI)-HR-TOF) at 4 GHz resolution mode were studied. Only 20% of the evaluated pesticides showed noticeable matrix effects (ME) due to coelution with natural products between tR = 3 and 11 min. Principal component analysis (PCA) of the detected coextractives grouped the mandarins and the orange varieties, but separated lemon, oranges, and mandarins from each other. Matrix effects were different among species but similar between varieties, forcing the determination of pesticide residues through matrix-matched calibration curves with the same fruit. Twenty-three natural products (synephrine, naringin, poncirin, glycosides of hesperitin, limonin, nomilin, and a few fatty acids, among others) were identified in the analyzed extracts. Twelve of the identified compounds coeluted with 28 of the pesticides under study, causing different matrix effects.

Degradation of imazalil, orthophenylphenol and pyrimethanil in Clementine mandarins under conventional postharvest industrial conditions at 4°C.

The degradation of the postharvest fungicides imazalil, orthophenylphenol, and pyrimethanil was studied on Clementine mandarins during packinghouse storage for a 28day period at 4°C. Fruits to which orthophenylphenol was applied, were treated with imazalil and pyrimethanil at doses of 1000 and 2000mgL(-1), using cascade application for the later and cascade and wax for the former. The decay of the three fungicides was evaluated using an in-house validated analytical procedure that includes the extraction and dispersive clean up of the samples followed by the GC-MS determination of the pesticide residues. The impact of fruit storage time on pesticide residues concentration was assessed. The residues found for the different application technologies were always below the established Maximum Residue Limits by the Codex Alimentarius and the European Union (5mgkg(-1) for imazalil, 7 and 8mgkg(-1) for pyrimethanil, and 10mgkg(-1) and 5mgkg(-1) for orthophenylphenol). The fungicides dissipated differentially. Pyrimethanil showed little degradation, if any, at both tested concentrations, but the half-life of imazalil on the fruit was 15-18days, independent of the application technology. Orthophenylphenol dissipated with a half-life of 15days. The initial imazalil residue found after cascade treatment was not significantly different between the doses studied (p<0.5), whereas when the fungicide was included in wax as an emulsifiable concentrate the initial and final imazalil residues were significantly different. Final residue levels after 28days of storage were 0.12-0.24mgkg(-1) for imazalil, 0.68mgkg(-1) for 2-phenylphenol and 0.56mgkg(-1) for pyrimethanil for all the evaluated treatments.

Pesticide Residues in Natural Products with Pharmaceutical Use: Occurrence, Analytical Advances and Perspectives

A pharmaceutical raw material is every active or inactive substance used in the manufacturing process of a pharmaceutical dosage form. According to their function in the medicament, they could be classified into two groups: (i) active ingredients with pharmacological activity; and (ii) excipients which allow the active ingredients dosification and makes suitable the route of administration (de la Rosa et al., 1995). In spite of the high number of synthetically produced pharmaceuticals and the progress in biotechnology and gene engineering, there are a number of raw materials of natural origin, which are still used for manufacturing active pharmaceutical products (Balandrin et al., 1985). Quality is a mandatory requirement in the materials to accomplish the Pharmaceutical ‘Good Manufacturing Practices’. Nowadays, the presence of pesticides in animal and vegetal commodities is a topic of public concern for the potential health hazards derived from them (WHO, 1998). The presence of pesticide residues in animal or vegetal raw materials can be originated in agricultural practices, environmental contamination or cross contamination. For example, oils rendered from whole fish and from fish offal represent an important dietary component in many areas of the world. In addition, fish oils are extensively used as ingredients in food and in dietary supplements for their therapeutic benefits in the treatment of cardiovascular, arthritic and dermatological diseases. Fish oils, however, are susceptible to contamination with lipophilic organic chemicals, in particular many organochlorine chemicals are now ubiquitous contaminants of marine ecosystems, but there is no specification on the pesticide residue allowed (Jacobs et al., 1997). The number of trace pollutants to be monitored is continually growing and the levels at which these compounds need to be determined are becoming lower. Multi-residue methods (MRMs) are the preferred strategy over single analyte or class residue methods (SRMs). Analytical features of the MRMs allow to cover a large range of pesticides in a single analysis. Many MRMs employing different extraction and clean-up techniques and a variety

Transfer of pesticides to the brew during mate drinking process and their relationship with physicochemical properties.

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 Henrys 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)

Erratum to: Evaluation of Three Multiresidue Methods for the Determination of Pesticides in Marijuana (Cannabis sativa L.) with Liquid Chromatography-Tandem Mass Spectrometry

Marijuana (non-medical cannabis) is a well-recognized psychoactive herbal drug used for recreational purposes. The aim of this work is to describe and compare the performance and suitability of selected methods to analyze pesticide residues in marijuana. The fitness of three typical pesticide multiresidue methods [acetate buffered QuEChERS (method A), a modified citrate buffered QuEChERS (method B) and citrate buffered QuEChERS (method C)] were tested in marijuana through the LC–MS/MS determination of 61 LC amenable pesticides. Considering recoveries at the highest level for the selected pesticides in marijuana, from the 61 target analytes, 37 (method A), 40 (method B) and 46 (method C) compounds gave accurate results (70–120 % range). Method C showed the best performance for the target analytes in terms of recoveries, precision, limits of quantitation and matrix effect. Marijuana showed to be a highly complex matrix. Most analytes suffered high signal suppression (ME <−50 %) for method B while medium (−50 to 20 %) to low (−20 to 0 %) signal suppression was found for methods A and C. Moreover, high coelution of coextractives with the target analytes was observed. A pilot survey with real samples revealed that seized and legally produced marijuana samples contained pesticides. Residues of diazinon (0.03 mg kg−1), tebuconazole (0.19 mg kg−1) and teflubenzuron (0.11 mg kg−1) were simultaneously detected in one marijuana sample. The establishment of MRLs in a legal consumption scenario such as in Uruguay seems to be necessary in the near future.

“Analysis of pesticide residues in fruits and vegetables using gas chromatography-high resolution time-of-flight mass spectrometry”

This work reports a study on the operational parameters and development of a rapid automatic method for determining pesticide residues in fruit and vegetables using gas chromatography full spectra mass acquisition time-of-flight accurate mass spectrometry (GC-TOF-MS) in electron ionization mode (EI) based on the use of an “in-house” accurate-mass database. The database contains 110 GC amenable compounds, with their main fragment ions obtained under electron ionization at 70 eV. In addition, it includes the retention times of each pesticide working at constant flow. This customized database was linked to commercial software, which extracted all the potential compounds of interest from the GC-TOF MS raw data for each sample and matched them against the database to search for the targeted compounds in the sample. Ethyl acetate extracts spiked at 10, 20, 50 and 100 μg kg−1 levels in tomato, orange and spring onion were tested using the automatic detection of the target pesticides; at 10 μg kg−1, 100% of pesticides in tomato, 97.8% of pesticides in spring onion and 95.6% in orange were detected. These results were obtained under an acquisition rate of 4 GHz (12000 FWHM) and a mass error tolerance of 5 ppm. The retention time window for detection and identification was ±0.2 min. Adequate linear responses in the 10–100 μg kg−1 range were obtained for all the compounds in all the matrices, although saturation effects were observed in some cases. The developed method was applied to real samples with the qualitative and quantitative results comparable to those obtained using GC-QqQ-MS/MS.

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.