Uma das classes químicas de herbicidas que merece particular atenção é a dos bipiridílicos, representada pelo paraquat e diquat. Atualmente, muitos países têm banido ou restringido o uso destes herbicidas devido à grande quantidade de casos de intoxicação acidental, suicídio e envenenamento (tentativa de homicídio) ocorridos no passado. Em contrapartida, o paraquat ainda é bastante utilizado em cerca de 130 nações, com prevalência em países subdesenvolvidos ou em vias de desenvolvimento. O presente trabalho tem por objetivo o estudo e o desenvolvimento de métodos analíticos semi-quantitativo e quantitativo em amostras biológicas (plasma e urina) e aplicação no diagnóstico e investigação da intoxicação aguda por paraquat e diquat. Análises semi-quantitativas de triagem foram realizadas pela técnica enzimática-colorimétrica. Análises confirmatórias foram realizadas pela técnica de cromatografia em fase gasosa acoplada à espectrometria de massa (GC-MS). Após o desenvolvimento e validação dos métodos, as análises foram aplicadas em amostras de pacientes suspeitos de intoxicação aguda por paraquat/diquat atendidos no Hospital Regional do Vale do Ribeira (Pariquera-Açu) e no Hospital de Clínicas da Universidade Estadual de Campinas (SP). Foram avaliadas a efetividade do teste rápido semi-quantitativo e a correlação das concentrações plasmáticas e urinárias do paraquat/diquat obtidas com o método por GC-MS com o grau de intoxicação e o prognóstico de sobrevida dos pacientes após o diagnóstico e tratamento. / One of the chemical classes of herbicides that deserve particular attention is that of bipyridyl, represented by paraquat and diquat. Currently, many countries have banned or restricted these herbicides since large number of accidental intoxication, poisoning and suicide attempt cases occurred in the past. In spite of this, paraquat is still used in more than 130 countries, with prevalence in developing countries. The aim of this work was the study and the development of a screening test and a quantitative analytical method in biological samples (plasma and urine) and their application in diagnosis and prognosis of acute paraquat and diquat intoxication. Semi-quantitative analyses were performed by an enzymatic-colorimetric technique. Confirmatory analyses were performed by a gas chromatographic-mass spectrometric (GC-MS) method. After the development and the validation of both methods, analyses were applied to samples from patients suspected of acute paraquat/diquat poisoning attended in Hospital Regional do Vale do Ribeira (Pariquera-Açu) and Hospital de Clínicas da Universidade Estadual de Campinas (SP). In this present paper, we also evaluated the effectiveness of the rapid test and the correlation of paraquat/diquat plasma and urinary concentrations obtained with the GC-MS method with the degree of intoxication and prognosis of survival of patients after diagnosis and treatment.

Pesticides in the United States are frequently used to control pests in many settings from residential homes to agricultural crops. Most pesticides, when used in accordance with their manufacturer's label are relatively safe, and will naturally degrade once exposed to the environment, however, these natural degradative processes can be hindered when introduced indoors. Furthermore, it has been shown that pesticides can easily bond to surface dislodgeable residues (SDRs) commonly known as dust. There are various methods that can be used to characterize the presence and exposure of pesticides indoors. Wipe sampling is one of the important methods commonly used to measure pesticides on surfaces due to its simple and inexpensive nature, however, several methods exist for wipe sampling and each method has varying steps involving different wiping material, pre-treatment of wipes, wetting solvent, surface type, collection pattern, and storage. The purpose of this literature review is to summarize concisely the methods from eighteen recent studies that used surface wipes to sample for pesticides from indoor environments. This report details the methods applied to perform the literature review, provide general wipe sampling information from government agencies, discuss other related surface sampling methods, provide a brief summary of wipe sampling methods applied in each study, and compare the methods applied to provide considerations for those seeking to use surface wipes for sampling pesticides. Overall, it would seem that there are more variations than similarities between wipe sampling methods from the literature reviewed. Similarities included the use of isopropyl alcohol (IPA) as the wetting solvent and how wipe samples were stored after collection. The differences in wiping materials, pre-treatment of wipes, surface types, and collection patterns still demonstrate the need for a standardized method. Until a standardized method is established, poor comparisons of study results will continue and knowledge gaps will remain.

Substances of natural and synthetic origin were studied using analytical, bioassay guided isolation, metabolomics and medicinal chemistry techniques. In a section focused on the plant family Marcgraviaceae, a validated method for the quantification of six pentacyclic triterpenes (α and β Amyrin lupeol, ursolic acid, betulin and betulinic acid) in the Souroubea spp was developed. Quantification of the triterpenes in the crude extracts was achieved using HPLC-APCI mass selective detection. The calibration curves for the five triterpenes evaluated were highly linear (r2 >0.993) and percentage recovery from spiked samples were greater than 94% for all compounds. The LOD for betulinic acid was 0.01 µg for betulinic acid on column and LOQ was 0.03 µg. The method was successfully applied to 41 crude extracts from leaf and stem of Souroubea spp, from two locations in Costa Rica. The method is suitable for quality control of raw materials used in the manufacture of natural health products. The use of modern metabolomic techniques, UHPLC-QTOF allowed the identification of five putative makers that can potentially be used in distinguishing between the two Souroubea species. The validated method was used in the quantification of the above triterpenes in a total of thirteen Marcgraviaceae species collected in Costa Rica. It was established that betulinic acid and β- Amyrin could be used as makers for this family of tropical vines. These same thirteen plants extracts were evaluated in antifungal and quorum sensing inhibition bioassays. Marcgravia nervosa was the only species that showed significant activity in both bioassays. Bioassay guided fractionation of the crude ethanolic extract of M. nervosa led to the identification of 2-methoxynaphthoquinone as the bioactive compound responsible for the bioactivity. The crude leaf ethanolic extract from M. nervosa showed a significant inhibition of QS comparable or somewhat better than D. pulchra extracts with the M. nervosa extract showing stronger inhibiting QS with a halo of 21.8mm, more than D. pulcra extracts which generated a halo of 15.9mm. The active quinone has a MIC of 85 µM against Saccharomyces cerevisiaBY4741 (haploid) and 100 µM against Saccharomyces cerevisiae BY4743 (diploid) compared to berberine (positive control) with a MIC 600 µM for both strains. This quinone is not present in any of the other twelve species of Marcgraviaceae available to us. In work focusing on organic synthesis, a total of 57 semi-synthetic derivatives of dillapiol, safrol and piperonal were prepared and evaluated for their inhibitory activity in a CYP 3A4 bioassay to assess their potential use as pesticide synergists. The synergistic activity of dillapiol has been improved 45 fold; analog 31 has an IC50 = 0.2 µM compared with dillapiol IC50= 9.18 µM. A number of other compounds structurally related to 31 showed similar levels of activity. A screening of a compound library identified the amino sulfoxide 3 as a potential lead for the design of a selective connexin blocker with potential application in the treatment of spinal cord injuries. The use of X-ray crystallography permitted the correction of the original structure assigned to 3. Once the structure was corrected a total of 6 analogs were prepared. Compound 3 has the highest inhibition of GJIC whereas compound 8 and compound 2, reduced anionic hemi-channel activity. Compound 2 also reduced the cationic activity of the hemi-channels.

Pesticide poisoning is a global health concern with approximately three million cases being reported on an annual basis. The latter includes both intentional and unintentional poisonings. Organophosphorus and carbamate insecticides are frequently found to be ‘responsible’ for pesticide poisoning in developing countries. In South Africa, aldicarb is the most potent carbamate pesticide and is sold in the informal markets as Temik. It is colloquially known as “Two step” or “Galephirimi” resulting in numerous cases of acute poisoning, especially in urban areas. Underreporting of suspected or confirmed pesticide poisoning cases has been a problem encountered in the national notification systems. Although a number of carbamate poisonings have been identified at the Pretoria Medico-Legal Laboratory, the presence of carbamates in post-mortem samples is rarely confirmed analytically. This may be ascribed to insufficient sample preparation, analytical methods not being sensitive enough or storage conditions not being optimal or too long before analysis takes place. It is well documented that most analytical errors occur during the pre-analytical phase, leading to a high prevalence of inconclusive results being attained. This may possibly be due to pre-analytical degradation, binding to biological matrix or the analytical method not been sensitive enough for detection in collected samples. Post-mortem redistribution factors such as physicochemical properties of the xenobiotic compounds (pH, volume of distribution, protein binding affinity, bacterial biotransformation and lipophilicity), characteristics of the matrix, specimen collection procedure and the use of preservatives may also influence the carbamate stability. The primary aim of the study was to optimise the sample preparation and analysis of biological matrices for select carbamates using LC-MS/MS method. Additionally, to analyse pesticide samples sold by street vendors as well as post-mortem samples collected from suspected cases of carbamate intoxication to determine whether the developed method can detect carbamates in real samples. Assessment of the aldicarb decay kinetics was done by spiking biological samples (whole blood, plasma, urine) collected from consenting healthy volunteers. Post-mortem samples (blood, urine, stomach content) of suspected carbamate poisoning cases, were screened for possible carbamate compounds and their metabolites or breakdown products. Optimisation and validation of the method was performed using a high-performance liquid chromatography (HPLC) system coupled to a triple quadrupole mass spectrometer following different extraction methods. The system was operated in positive electrospray ionisation (ESI+) mode. Different columns, mobile phase buffers and cartridges were used to compare the chromatographic separation of the carbamate compounds. Validation according to ICH guidelines was done for aldicarb. A set of matrix-matched standard calibration curves, was constructed using Analyst (version 1.5.2) software. Initial sample preparation of carbamate pesticides using three different SPE cartridges proved to be unreproducible with poor recoveries of specific compounds due to the wide range of carbamate pesticide polarities, so this was abandoned for the stability testing and forensic samples tested. About 85% reduction of the concentration of aldicarb was seen in whole blood only at ambient temperature but was stable at lower temperatures. Stability proved to be better in plasma compared to whole blood, for aldicarb and its oxidation products. Aldicarb was stable in urine stored with boric acid preservative. The ideal storage temperature for biological samples containing these carbamate compounds was found to be -80°C. During analysis of forensic samples, unknown peaks were consistently detected which are believed to correspond to adulterants and diluents which are added to “backstreet” pesticides. A possible match of an organophosphate, terbufos, found in some “backstreet” pesticide products was detected in some of the post-mortem samples. Considering their different physicochemical properties and that several factors can influence the biodegradation of carbamate compounds, no extrapolation of results from one carbamate compound to another can be formulated. The development and validation of an analytical method to quantify aldicarb and its oxidation products (aldicarb sulfoxide and sulfone) in whole blood, plasma and urine, using the protein precipitation method and LC-MS/MS was successful. Method validation to quantify ten standard carbamate pesticides using SPE and UPLC-q-TOF/MS was unsuccessful. The LC-MS/MS technique was found to be a suitable tool for the quantitation of aldicarb and its oxidation products in typical post-mortem sample matrices. / Dissertation (MSc (Medical Criminalistics))--University of Pretoria, 2021. / Faculty of Health Sciences Research Committee / Department of Pharmacology / University of Pretoria Masters research and research award grant / Forensic Medicine / MSc (Medical Criminalistics) / Unrestricted

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / The incidence of the disease in horticultural crops is one of the important problems that affect the production of fruits, vegetables and flowers. Regular monitoring of crops for early diagnosis and treatment with pesticides or removal of the affected crop is part of the solution to minimize crop loss. The monitoring of crops by human labor is expensive, time consuming, prone to errors due to insufficient knowledge of the disease and highly repetitive at different stages of crop growth. These needs have motivated to design the mobile robot with vision sensors for navigation through the field. The robot has been designed in the Autodesk Inventor software. Programming for navigation is done in the Arduino Mega 2560 tool. Image capture has been performed using the RGB camera. Image processing for the identification of the disease and its representation in a graphical user interface has been performed using an algorithm in MATLAB R2018B that interacts with the Arduino tool through a communication bus. The system developed consists of the design of a prototype that uses simple and cost effective equipment such as Raspberry Pi, RGB camera, two motors and sensors that allow the autonomous fumigation of corn crops. / Revisión por pares

No description available.

Previous monitoring studies by federal agencies such as the United States Geological Survey have shown that environmental contaminants rarely occur as single compounds but, rather, as mixtures. In aquatic ecosystems, mixtures of these compounds are often complex, sometimes containing dozens of compounds across a number of different chemical classes. Non-target aquatic organisms are frequently exposed to varying levels of contaminants based upon the physical properties of the chemicals, such as water solubility, and life-cycle habits of the individual organisms. In addition to this, past research has indicated that the presence of one class of contaminant may have an influence on the toxicities of other chemical classes. Water-only toxicity testing has historically provided a means by which researchers can rapidly determine the toxic effects of water-soluble compounds such as triazine herbicides and organophosphate insecticides. However, many legacy pesticides, such as organochlorine, and some current-use pesticides, such as pyrethroids, are strongly hydrophobic, and suspended or bedded sediments, rather than water, would generally be more appropriate matrices for monitoring. Yet sampling of sediments and quantification of residues of these pesticides is often lacking. Similarly, there have been few studies examining the toxicity of mixtures of these compounds in sediment. The first goal of this research was to examine the effects of select triazine herbicides on organophosphate insecticide toxicity utilizing water-only toxicity test with the aquatic amphipod Hyalella azteca. The second goal was to analyze an existing database of chemical concentrations using a toxicity-based screening approach in order to estimate the environmental hazard posed by mixtures of pyrethroid, organochlorine, and organophosphate insecticides in sediment to H. azteca. The third goal of this research was to examine the toxic effects of mixtures of different pyrethroid insecticides to H. azteca using compounds identified as most relevant from the screening phase of the study. The fourth goal of this research was to examine how pyrethroid and organochlorine insecticides partition between different size fractions within sediment and detritus, as well as between sediments with differing organic carbon content, and the resulting effects to compound toxicity and bioavailability. The final goal of this research was to examine potential modifications to bifenthrin sediment partitioning, toxicity, and bioaccessibility resulting from various dissolved salt concentrations in overlying water using H. azteca and Chironomus dilutus as reference organisms. Together, the individual objectives of this study provide a thorough and multi-tiered approach to determining the occurrence, environmental fate, biological effects, and bioavailability of frequently detected and co-occurring environmental contaminants in both agricultural and urban landscapes.

No description available.

No description available.

The idiophasic production of nonspecific extracellular enzymes by the Basidiomycete fungus Phanerochaete chrysosporium, referred to as the ligninolytic system, has been reported by many researchers to be capable of degrading a broad spectrum of environmentally persistent compounds including some alkyl halide chemicals. Cultivation of the fungus and the ability of the ligninolytic system to degrade the alkyl halide pesticide toxaphene were explored in pure liquid cultures. The effects of culture growth temperature and toxaphene concentration were evaluated. The extent of toxaphene conversion with time was determined using three different indicators; toxaphene gas chromatographic elution patterns, the determination of free chloride concentrations by ion chromatography analyses, and the distribution of chloride in aqueous and biomass fractions via total organic halide analyses. Oxidation of the azo dye, Orange II, via spectrophotometric measurements was employed to determine the activity and reactivation of the fungal ligninolytic system. Degradation of toxaphene in the P. chrysosporium cultures was limited, with a maximum of 7% of the original mass of chloride originating from the toxaphene being released over a three week period. The main removal mechanism of the toxaphene from solution was observed to be adsorption to the mycelium biomass. Ligninolytic activity was equally active at temperatures less than optimum for maximum growth of the fungus which implies that the ligninolytic system can be effective with reduced temperature requirements. Elevated pH conditions did not effect ligninolytic activity indicating that high more neutral pHs, which are characteristic of soil properties, do not inhibit ligninolytic activity. Reactivation of the ligninolytic system was accomplished in a nonimmersed liquid culture system. The immobilized configuration appeared to be an effective system for cultivating the ligninolytic system on a continuous basis. / Master of Science