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Nanocrystals of zeolites with shortened diffusional pathways compared to bulk counterparts are attractive catalysts, but their direct synthesis often remains challenging and expensive. Here, we describe the utility of p-phenylenedimethylene-bis(trimethylammonium) dichloride, an organic diquaternary ammonium compound that can be easily prepared, as an effective organic structure-directing agent (OSDA) for obtaining several zeolites composed of agglomerated nanocrystals. By modifying the gel composition (NaOH/Si and Si/Al ratios) and crystallization time, synthesis can be tuned to obtain mordenite, EU-1, and ZSM-12 zeolites. 13C NMR spectra of the occluded OSDA reveal subtle differences in host-guest interactions between the OSDA and the respective zeolites, which derives from the flexibility of the OSDA. The relatively strong interaction between the OSDA and inorganic aluminosilicate precursor species during the induction period explains how small zeolite nanocrystals are obtained. Nanosized EU-1 and ZSM-12 significantly outperform their corresponding bulk counterparts as acid catalysts in the methanol-to-hydrocarbons reaction and the alkylation of benzene with benzyl alcohol, respectively.

[Resumen]: Los efluentes de aguas residuales presentan contaminantes emergentes que deben ser tratados, como los herbicidas diquat y glifosato. El objetivo de este trabajo es la degradación de esos herbicidas mediante procesos de oxidación avanzada como lo son la fotólisis y la fotocatálisis. Como parte esencial del proceso de fotocatálisis, también se realizó el estudio de la adsorción de los herbicidas sobre el fotocatalizador. Las medidas de seguimiento se realizaron en un espectrofotómetro, se midió la cantidad de carbono orgánico total y se tomaron valores de pH al inicio y final de cada reacción., [Resumo]: Os efluentes de augas residuais presentan contaminantes emerxentes que deben ser tratados, como os herbicidas diquat e glifosato. O obxectivo deste traballo é a degradación desos herbicidas mediante procesos de oxidación avanzada como o son a fotólisis e a fotocatálisis. Como parte esencial do proceso de fotocatálise, tamén se realizou o estudo da adsorción dos herbicidas sobre o fotocatalizador. As medidas de seguimento leváronse a cabo nun espectrofotómetro, mediuse a cantidade de carbono orgánico total e tomáronse valores de pH ao inicio e final de cada reacción., [Abstract]:Wastewater effluents present emerging pollutants that deserve treatment, such as diquat and glyphosate, both classified as herbicides. The main objective of this work is the degradation of these herbicides through advanced oxidation processes such as photolysis and photocatalysis. As an essential part of the photocatalysis process, the adsorption of the herbicides onto the photocatalyst was also carried out. Follow-up measurements were carried out in a spectrophotometer, the amount of total organic carbon was measured, and pH values were taken at the beginning and end of each reaction.

[Resumen] En este estudio se evalúa el uso de aguas residuales y de los contaminantes diquat y glifosato como agua de riego pre y post tratamiento, de una especie de interés comestible, Brassica rapa, y de una especie de interés ornamental, Lolium perenne. Varias de las disoluciones preparadas han sido tratadas con fotólisis, fotocatálisis y adsorción sobre fotocatalizador. Se realizaron ensayos de germinación para establecer la viabilidad de las semillas y su capacidad germinativa en contacto con las disoluciones ya tratadas. También se llevaron a cabo ensayos en plantas adultas regadas durante una semana con las disoluciones preparadas, con el objetivo de medir la capacidad fotosintética y cantidad de fenoles totales en las hojas de ambas especies., [Abstract] This study evaluates the use of residual waters and the contaminants diquat and glyphosate as irrigation water before and after treatment, of one species of edible interest, Brassica rapa, and one species of ornamental interest, Lolium perenne. Some of the prepared solutions were treated with photolysis, photocatalysis and adsorption on photocatalyst. Germination assays were made to establish the viability of the seeds and their germinative capacity in contact with the pretreated solutions. Assays on adult plants irrigated with the prepared solutions for a week were also made, aiming to measure the photosynthetic capacity and total phenol quantity of the leaves of both species.

[Resumen]: Los efluentes de aguas residuales presentan contaminantes emergentes que deben ser tratados, como los herbicidas diquat y glifosato. El objetivo de este trabajo es la degradación de esos herbicidas mediante procesos de oxidación avanzada como lo son la fotólisis y la fotocatálisis. Como parte esencial del proceso de fotocatálisis, también se realizó el estudio de la adsorción de los herbicidas sobre el fotocatalizador. Las medidas de seguimiento se realizaron en un espectrofotómetro, se midió la cantidad de carbono orgánico total y se tomaron valores de pH al inicio y final de cada reacción., [Resumo]: Os efluentes de augas residuais presentan contaminantes emerxentes que deben ser tratados, como os herbicidas diquat e glifosato. O obxectivo deste traballo é a degradación desos herbicidas mediante procesos de oxidación avanzada como o son a fotólisis e a fotocatálisis. Como parte esencial do proceso de fotocatálise, tamén se realizou o estudo da adsorción dos herbicidas sobre o fotocatalizador. As medidas de seguimento leváronse a cabo nun espectrofotómetro, mediuse a cantidade de carbono orgánico total e tomáronse valores de pH ao inicio e final de cada reacción., [Abstract]:Wastewater effluents present emerging pollutants that deserve treatment, such as diquat and glyphosate, both classified as herbicides. The main objective of this work is the degradation of these herbicides through advanced oxidation processes such as photolysis and photocatalysis. As an essential part of the photocatalysis process, the adsorption of the herbicides onto the photocatalyst was also carried out. Follow-up measurements were carried out in a spectrophotometer, the amount of total organic carbon was measured, and pH values were taken at the beginning and end of each reaction.

This study was conducted to demonstrate that dietary puerarin supplementation alleviates oxidative stress in the small intestine of diquat-challenged piglets. The results showed that puerarin administration markedly alleviated diquat-induced intestinal injury, which was indicated by the improvement of intestinal morphology, cell proliferation and barrier function. One of the potential mechanisms responsible for this was the decrease in oxidative stress, as evidenced by the increase in activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in the small intestine. Puerarin increased the protein expression levels of NF-E2-related factor 2 (Nrf2) and its downstream enzymes, including heme oxygenase 1 (HO-1), glutamate-cysteine ligase catalytic and its modifier subunit (GCLc and GCLm) in the jejunal mucosa of diquat-induced piglets. Puerarin administration improved intestinal morphology, cell proliferation, and barrier function, and increased Nrf2 and its downstream enzymes. These findings indicate that the dietary supplementation of puerarin attenuates the oxidative stress involving Nrf2 signaling pathways in diquat-challenged piglets.

This study was designed to evaluate the antioxidant and anti-inflammatory effects of Eucommia ulmoides flavones (EUF) using diquat-challenged piglet models. A total of 96 weaned piglets were randomly allotted to 1 of 3 treatments with 8 replication pens per treatment and 4 piglets per pen. The treatments were basal diet, basal diet + diquat, and 100 mg/kg EUF diet + diquat. On day 7 after the initiation of treatment, the piglets were injected intraperitoneally with diquat at 8 mg/kg BW or the same amount of sterilized saline. The experiment was conducted for 21 days. EUF supplementation improved the growth performance of diquat-treated piglets from day 14 to 21. Diquat also induced oxidative stress and inflammatory responses and then impaired intestinal morphology. But EUF addition alleviated these negative effects induced by diquat that showed decreasing serum concentrations of proinflammatory cytokines but increasing antioxidant indexes and anti-inflammatory cytokines on day 14. Supplementation of EUF also increased villi height and villous height, crypt depth, but decreased the histopathological score and MPO activity compared with those of diquat-challenged pigs fed with the basal diet on day 14. Results indicated that EUF attenuated the inflammation and oxidative stress of piglets caused by diquat injection.

This study was designed to evaluate the antioxidant and anti-inflammatory effects of Eucommia ulmoides flavones (EUF) using diquat-challenged piglet models. A total of 96 weaned piglets were randomly allotted to 1 of 3 treatments with 8 replication pens per treatment and 4 piglets per pen. The treatments were basal diet, basal diet + diquat, and 100 mg/kg EUF diet + diquat. On day 7 after the initiation of treatment, the piglets were injected intraperitoneally with diquat at 8 mg/kg BW or the same amount of sterilized saline. The experiment was conducted for 21 days. EUF supplementation improved the growth performance of diquat-treated piglets from day 14 to 21. Diquat also induced oxidative stress and inflammatory responses and then impaired intestinal morphology. But EUF addition alleviated these negative effects induced by diquat that showed decreasing serum concentrations of proinflammatory cytokines but increasing antioxidant indexes and anti-inflammatory cytokines on day 14. Supplementation of EUF also increased villi height and villous height, crypt depth, but decreased the histopathological score and MPO activity compared with those of diquat-challenged pigs fed with the basal diet on day 14. Results indicated that EUF attenuated the inflammation and oxidative stress of piglets caused by diquat injection.

Se describe el proceso de recolección del cultivo de la chufa en Valencia, desde sus labores preparatorias (aplicación de herbicida desecan y quema) hasta el tamizado del suelo.

Se describe el proceso de recolección del cultivo de la chufa en Valencia, desde sus labores preparatorias (aplicación de herbicida desecan y quema) hasta el tamizado del suelo.

Se describe el proceso de recolección del cultivo de la chufa en Valencia, desde sus labores preparatorias (aplicación de herbicida desecan y quema) hasta el tamizado del suelo.

Se describe el proceso de recolección del cultivo de la chufa en Valencia, desde sus labores preparatorias (aplicación de herbicida desecan y quema) hasta el tamizado del suelo.

Noxon Rapids Reservoir, Montana, is one of several large impoundments on the Lower Clark Fork River, stretching for over 48 km (30 miles) with a surface area of 3,120 ha (7,700 acres). Management strategies were evaluated for their effectiveness in controlling invasive plant problems in the reservoir, specifically with Eurasian watermilfoil and curlyleaf pond-weed. A 3-year field program was developed to evaluate the effectiveness of aquatic herbicides to selectively control the invasive plants. The herbicide endothall (Aquathol K) was applied to four plots totaling 5.5 ha (13.6 acres) at 3000 g ai/L (3 ppm); diquat (Reward ) was applied to four plots totaling 3.3 ha (8.1 acres) at 370 g ai/L (0.37 ppm); and a combination of both products was applied to four plots totaling 4.7 ha (11.5 acres), with endothall at 1500 g ai/L (1.5 ppm) and diquat at 190 g ai/L (0.19 ppm). Herbicides were applied by boat using a variable-depth injection system. Aqueous herbicide dissipation was monitored in selected plots. Bulk water exchange processes were also measured. Quantitative surveys were conducted in each plot to assess the plant community at pretreatment, and at 6 weeks and 52 weeks post treatment., The original document contains color images.

Diquat (DQ) neurotoxicity mechanisms are unknown, although, it's systemic toxicity is mediated by free radical reactions. The role of glutathione cycle was assessed by glutathione reductase (GR) applied in the pre-treatment of DQ poisoning. Wistar rats were used and tested compounds were administered intrastriatally (i.s.) in one single dose. Total glutathione (tGSH), glutathione disulfide (GSSG) and glutathione peroxidase (GPx) were measured in the vulnerable brain regions (VBRs) (striatum, hippocampus and cortex), at 30 minutes, 24 hours and 7 days post treatment. Results from the intact and the sham operated groups were not statistically different. Rapid spatial spreading of oxidative stress was confirmed in the examined VBRs.. Mortality (30-40%, within 24hrs) and signs of lethargy were observed in the DQ group. Activity of GPx activity was elevated and GSSG/GSH was higher in the examined VBRs during the experiment, compared to the controls. The i.s. pre-treatment with GR achieved neuroprotective role against DQ induced neurotoxicity, based on animal survival, absence of lethargy and decreased GPx activity and GSSG/GSH in the examined VBRs during the experiment, compared to the DQ group. Our results confirmed that oxidation of GSH was the reason for the reduced antioxidative defense against DQ neurotoxicity., Mehanizmi neurotoksičnosti dikvata (DK) su nepoznati, mada se zna da je sistemska toksičnost posredovana reakcijama slobodnih radikala. Uloga glutationskog ciklusa je isptivana primenom glutation reduktaze (GR) u predtretmanu trovanja DK. Wistar pacovi su korišćeni i testirana jedinjenja intrastrjiatalno (i.s.) primenjena u jednokratnoj dozi. Ukupni glutation (tGSH), glutation-disulfid (GSSG) i aktivnost glutation peroksidaze (GPx) su mereni u selektivno osetljivim regionima mozga (strijatum, hipokampus i korteks), 30. minuta, 24. sata i 7. dana posle tretmana. Rezultati netretiranih (intaktna grupa) i lažno operisanih pacova se ne razlikuju statistički. Vremensko i prostorno širenje oksidativnog stresa je potvrđeno kod ispitivanih moždanih struktura. Mortalitet (30-40%, u roku od 24 casa) i znaci letargije su uočeni u samo u DK grupi. Statistički povećana aktivnost GPx, kao i odnosa GSSG/GSH u ispitivanim moždanim strukturama tokom eksperimenta, potvrđuje oksidativno narušenu ravnotežu i oštećenja moždanog tkiva. Predtretman i.s. sa GR je ispoljio neurozaštitni efekat od neurotoksičnosti DK, bazirano na preživljavanju životinja, odsustvu letargije i smanjenoj aktivnost GPx i odnosa GSSG / GSH ispitivanih moždanih struktura tokom eksperimenta, u odnosu na DK grupu. Naši rezultati ukazuju da je oksidacija GSH kljucna za smanjenje antioksidativne odbrane od DK neurotoksicnosti.

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue en PDF.Les maladies d'Alzheimer (MA) et de Parkinson (MP) sont les deux formes les plus communes de maladies neurodégénératives liées à l'âge. Elles touchent des millions d'individus à travers le monde. Dans un premier temps, les caractéristiques pathologiques de la MA comprennent la déposition de plaques séniles extracellulaires composées du peptide d'amyloïde beta (AB) et des enchevêtrements neurofibrillaires extracellulaires, composés de la protéine tau hyperphosphorylée ainsi que de la perte neuronale. Dans un second temps, la MP est caractérisée par la perte sélective des neurones dopaminergiques au niveau de la substance noire compacta (SNpc) dans le cerveau et la déposition de l'alpha (a)-synucléine contenue dans les corps de Lewy. La composante génétique contribue à <10% des diverses formes familiales de la MA et de la MP et prés de 90% de MA et de MP des formes sporadiques. En Inde, de nombreuses plantes médicinales sont utilisées comme agents nootropes et toniques pour le cerveau dans le but de restaurer le déclin mental lié à l'âge. Le taux d'incidence entre l'âge et la MA dans les milieux ruraux d'Inde sont au moins trois fois plus faibles que les taux des populations américaines de référence. Cependant, la prévalence de la MP chez les indiens asiatiques est aussi trois fois inferieure à celle des caucasiens britanniques. Contrairement aux américains, il n'existe pas de lien entre l'âge et la perte des neurones du SNpc chez les indiens asiatiques. La Bacopa monniera (BM) est l'une des plus importante plante médicinale utilisée dans le système de médecine traditionnelle en Inde. Elle est utilisée comme agent nootrope et comme stimulant pour le cerveau dans le but de restaurer les déclins cognitifs liés à l'âge. Il a été rapporté que les bacosides

Most commonly observed central nervous system (CNS) effects induced by systemic toxicity of herbicide diquat (DQ) are general depression and lethargy. Generally, it is accepted that DQ exerts its toxicity through the production of superoxide anion radical (O2 ●-) during its redox metabolism in the presence of molecular oxygen, which further initiates radical chain reaction, contributing developing of oxidative stress (OS) as well. Mechanisms of DQ neurotoxic effect is not rationalized till now. The objective of the study was to examine whether OS contributes to DQ neurotxicity. For this purpose, male Wistar rats were intrastriataly (i.s.) treated with DQ and oxidative status parameters such as: superoxide anion radical (O2 ●-); nitrates (NO3 -), as a final metabolite of reactive nitogen species; malondialdehyde (MDA), an indicator of lipid peroxidation; activity of superoxide dismutase (SOD); glutathione peroxidase (GPx), and glutathione (GSH), were measured in the hippocampus at 30 minutes, 24 hours and 7 days post treatment. Noteworthy, mortality rate (30 - 40 %) was observed in the group of rats treated with DQ, within 2-3 hours after awakening from anesthesia. Additionally, lethargy was the only neurological symptom observed in that group. Analyzed parameters indicate that OS mediates DQ neurotxicity, which is documented with significant increase of lipid peroxidation., Najčešće zapaženi efekti sistemskog trovanja herbicidom dikvatom (DK) na centralni nervni sistem (CNS) su opšta depresija i letargija. Opšte je prihvaćeno da se toksičnost DK ostvaruje posredstvom povećanog stvaranja superoksid anjon radikala (O2 ●-) tokom njegovog redoks metabolizma, u prisustvu molekularnog kiseonika, koji dalje inicira lančanu reakciju radikalskog tipa i razvoj oksidativnog stresa (OS). Do danas mehanizmi neurotoksičnog efekta DK nisu u potpunosti poznati. Cilj ove studije je bio da ispitamo da li OS posreduje u neurotoksičnosti indukovanoj DK. Eksperiment je sproveden na mužjacima Wistar pacova, intrastrijatalno tretiranih (i.s.) DK. Parametri oksidativnog statusa, kao što su: superoksid anjon radikal (O2 ●-), nitrati (NO3 -), kao finalni metaboliti reaktivnih vrsta azota; malondialdehid (MDA), indikator lipidne peroksidacije; aktivnost enzima; superoksid dizmutaze (SOD) i glutation peroksidaze (GPx); i glutation (GSH) mereni su u hipokampusu, 30 minuta, 24 sati i 7 dana posle tretmana. Stopa smrtnosti od 30 do 40 % ustanovljena je u grupi pacova tretiranih DK, tokom 2-3 sata od buđenja iz anestezije. Dodatno, pacovi ove grupe su pokazali neurološke simptome letargije. Značajno povećana lipidna peroksidacija pokazuju da OS posreduje u neurotoksičnom odgovoru indukovanom i.s. primenom DK.

In this study we examined if the response of the cortex against diquat (DQ), intrastriatally (i.s.) applied to Wistar rats, was mediated by oxidative/nitrosative stress (OS/NS). In particular, we were focused on the glutathione (GSH) antioxidative role, thus we applied i.s. glutathione reductase (GR) in the pre-treatment of DQ administration. Superoxide anion radical (O2 •-), nitrate (NO3 -), malondialdehyde (MDA) and superoxide dismutase (SOD), were measured in ipsi- and contra- lateral sides of the cortex, at 30 minutes, 24 hours and 7 days post treatment. The redox balance was not significantly changed in the cortex of sham operated and intact groups. Also, no differences were observed between the ipsi- and contra- lateral side of the cortex. Lethargy and mortality (30-40%) of the animals in the DQ group within 24 hrs, coincided with rapidly developed lipid peroxidation supported by OS/NS upon i.s. DQ administration. Strong redox potential of DQ probably resulted in a huge deprivation of molecular oxygen. The pretreatment with GR acted neuro-protectively, based on animal survival and absence of lethargy, although, lipid peroxidation was not developed in the GR+DQ group, OS was documented by a high concentration of O2 •- (within 24 hrs), descending and eventually inhibiting SOD activity (at 7 days)., U ovoj studiji smo ispitali da li je oksidativni/nitrosativni stres (OS/NS), uključen u odgovor korteksa Wistar pacova nakon intrastrijatalne (i.s.) izloženosti dikvatu (DK). Posebno smo ispitivali značaj antioksidativne uloge glutationa (GSH), zbog čega smo primenili glutation reduktazu (GR) u predtretmanu davanja DK. Superoksid anjon radikal (O2•¯), nitrati (NO3¯), malondialdehid (MDA) i superoksid dismutaza (SOD), su mereni u obostranom korteksu (ipsi- i kontrastrana), nakon 30 minuta, 24 sati i 7 dana od tretmana. Redoks balans se nije značajno promenio u korteksu lažno operisanih i netretiranih pacova. Takođe, ne postoji statistički značajna razlika između ipsi- i kontra- strane korteksa. Letargija i mortalitet (30-40%) kod životinja u DK grupi su uočene tokom 24 časa od i.s. trovanja DK, što se poklopilo sa naglim razvojem OS/NS i lipidne peroksidacije. Visok redoks potencijal DK verovatno rezultira opsežnim utroškom molekularnog kiseonika. Zaključeno je da je ostvaren neuroprotektivni učinak predtretmana sa GR, na osnovu preživljavanja životinja i odsustva letargije. Lipidna peroksidacija nije bila razvijena u grupi predtretiranoj sa GR ali je ipak izmerena visoka koncentracija O2•¯ (tokom 24 sata) koja zatim opada i na kraju 7. dana u potpunosti inhibira aktivnost SOD.

Introduction: Contact herbicide diquat (DQ), redox cycling compound, mediates its systemic toxicity throughout the enlarged production of free radicals. Target organs are liver and kidney in humans. To-date, the mechanism of DQ-induced neurotoxicity has not been rationalized. Objective: The objectives of the study were to examine the ability of DQ to induce oxidative stress (OS) and/or nitrosative stress (NS) upon intrastriatal (i.s.) administration and to investigate the role of nitric oxide (NOx) using NG-nitro-L-arginine methyl ester (L-NAME), a non-selective inhibitor of nitric oxide synthase (NOS) in the pretreatment of DQ i.s. administration. Material and Methods: The experiment was conducted on Wistar rats, randomly divided in experimental groups, receiving different treatments i.s. applied. Parameters of OS/NS such as: superoxide anion radical (O-2(center dot-)), superoxide dismutase (SOD), malondialdehyde (MDA) and nitrates (NO3-) were measured in the cortex (bilaterally), at 30th min, 24 hours and 7 days after the treatments. Results: Lethargy and high mortality rate were observed only in the DQ group (within 24 hours and 2-3 hours, respectively) after awakening from anesthesia. Markedly increased production of NOx and O-2(center dot-) along with elevated lipid peroxidation altogether contributed to DQ neurotoxicity. The most importantly, the L-NAME i.s. pretreatment protected treated animals from dying and diminished OS/NS response against DQ-induced neurotoxicity. Conclusion: The i.s. pretreatment with L-NAME resulted in neuroprotection against DQ neurotoxity, based on animal survival and reduced LPO in the cortex.

Diquat is a bipyridyl herbicide with nephrotoxic effects. This in vitro study demonstrates a colorimetric test for detection of diquat in human urine. Urine specimens using ten concentrations of diquat herbicide solution and controls for urine and glyphosate were prepared. A two-step assay (addition of bicarbonate followed by sodium dithionite) was performed, with a resulting color change of the original solution for each specimen. Color change intensity was noted immediately and after 30 min, by gross visual inspection. A green color with concentration-dependent intensity was detected in all specimens, in which concentrations of diquat solution ranged from 0.73 to 730 mg/L. This colorimetric effect disappeared after 30 min. The sodium bicarbonate/dithionite test may be useful as a qualitative bedside technique for the detection of urinary diquat in the appropriate clinical setting.

Diquat is a bipyridyl herbicide with nephrotoxic effects. This in vitro study demonstrates a colorimetric test for detection of diquat in human urine. Urine specimens using ten concentrations of diquat herbicide solution and controls for urine and glyphosate were prepared. A two-step assay (addition of bicarbonate followed by sodium dithionite) was performed, with a resulting color change of the original solution for each specimen. Color change intensity was noted immediately and after 30 min, by gross visual inspection. A green color with concentration-dependent intensity was detected in all specimens, in which concentrations of diquat solution ranged from 0.73 to 730 mg/L. This colorimetric effect disappeared after 30 min. The sodium bicarbonate/dithionite test may be useful as a qualitative bedside technique for the detection of urinary diquat in the appropriate clinical setting.

Production of efficiently synthesizable, strongly associating crown ether-based cryptands is desired for pseudorotaxane complexation of bipyridinium guests to produce suprapolymers and supramolecularly-linked block copolymers. Cryptands based on bis(meta-phenylene)-32-crown-10 (BMP32C10) were synthesized. The functionality of phenylenemethanol-BMP32C10 cryptand III-3 (Ka = 2.0 x 104 M-1) did not negatively affect binding strength, although the strength of complexation is marginal to achieve the desired suprapolymers. The cryptand dimethylpyridyl-BMP32C10 IV-2 was synthesized in an attempt to improve over the binding ability of the pyridyl-BMP32C10 cryptand IV-1; instead, interesting host design insights were discovered as binding strengths were reduced over 1000-fold. The crystal structure of IV-2 shows acyl-aryl conjugation which limits the host's ability to accept guests. Synthesis of larger cis-di(carbomethoxybenzo)-3n-crown-n crown ethers was explored using the high concentration, template technique previously reported for cDB24C8 diester. cDB30C10 diester (V-1c) was produced in 93% yield; the desired pyridyl-cDB30C10 cryptand V-12 binds paraquat strongly (Ka = 1-2x105 M-1) and diquat stronger than any other host (Ka = 1.9x106 M-1), both in 1:1 fashions; association constants were measured by ITC. X-ray crystallography of the complexes shows the cryptand's para arm is too far away to interact with paraquat and the host has numerous bifurcated interactions with diquat, explaining the difference in binding strengths. Syntheses of the regioisomers of cDB27C9 diester was also explored; the cyclization yields (cDB27C9S, VI-2: 59% and cDB27C9L, VI-3: 44%) are lower, likely due to poor attack angles due to mismatched arm length in cyclization, than the equivalent length ethyleneoxy-armed cDB24C8 and cDB30C10. Modeling of the cryptand isomers, pyridyl-cDB27C9S and pyridyl-cDB27C9L, showed that the former should improve para arm interaction with paraquat, but should be s

A simple, economic, sensitive and rapid method for the determination of the pesticide diquat was described. This new method was based on the coupling of flow injection analysis methodology and direct chemiluminescent detection; to the authors' knowledge, this approach had not been used up to now with this pesticide. It was based on its oxidation with ferricyanide in alkaline medium; significant improvements in the analytical signal were achieved by using high temperatures and quinine as sensitiser. Its high throughput (144 h(-1)), together with its low limit of detection (2 ng mL(-1)), achieved without need of preconcentration steps, permitted the reliable quantification of diquat over the linear range of (0.01-0.6) mu g mL(-1) in samples from different origins (river, tap, mineral and ground waters), even in the presence of a 40-fold concentration of paraquat, a pesticide commonly present in the commercial formulations of diquat.

Production of efficiently synthesizable, strongly associating crown ether-based cryptands is desired for pseudorotaxane complexation of bipyridinium guests to produce suprapolymers and supramolecularly-linked block copolymers. Cryptands based on bis(meta-phenylene)-32-crown-10 (BMP32C10) were synthesized. The functionality of phenylenemethanol-BMP32C10 cryptand III-3 (Ka = 2.0 x 104 M-1) did not negatively affect binding strength, although the strength of complexation is marginal to achieve the desired suprapolymers. The cryptand dimethylpyridyl-BMP32C10 IV-2 was synthesized in an attempt to improve over the binding ability of the pyridyl-BMP32C10 cryptand IV-1; instead, interesting host design insights were discovered as binding strengths were reduced over 1000-fold. The crystal structure of IV-2 shows acyl-aryl conjugation which limits the host's ability to accept guests. Synthesis of larger cis-di(carbomethoxybenzo)-3n-crown-n crown ethers was explored using the high concentration, template technique previously reported for cDB24C8 diester. cDB30C10 diester (V-1c) was produced in 93% yield; the desired pyridyl-cDB30C10 cryptand V-12 binds paraquat strongly (Ka = 1-2x105 M-1) and diquat stronger than any other host (Ka = 1.9x106 M-1), both in 1:1 fashions; association constants were measured by ITC. X-ray crystallography of the complexes shows the cryptand's para arm is too far away to interact with paraquat and the host has numerous bifurcated interactions with diquat, explaining the difference in binding strengths. Syntheses of the regioisomers of cDB27C9 diester was also explored; the cyclization yields (cDB27C9S, VI-2: 59% and cDB27C9L, VI-3: 44%) are lower, likely due to poor attack angles due to mismatched arm length in cyclization, than the equivalent length ethyleneoxy-armed cDB24C8 and cDB30C10. Modeling of the cryptand isomers, pyridyl-cDB27C9S and pyridyl-cDB27C9L, showed that the former should improve para arm interaction with paraquat, but should be s

A simple, economic, sensitive and rapid method for the determination of the pesticide diquat was described. This new method was based on the coupling of flow injection analysis methodology and direct chemiluminescent detection; to the authors' knowledge, this approach had not been used up to now with this pesticide. It was based on its oxidation with ferricyanide in alkaline medium; significant improvements in the analytical signal were achieved by using high temperatures and quinine as sensitiser. Its high throughput (144 h(-1)), together with its low limit of detection (2 ng mL(-1)), achieved without need of preconcentration steps, permitted the reliable quantification of diquat over the linear range of (0.01-0.6) mu g mL(-1) in samples from different origins (river, tap, mineral and ground waters), even in the presence of a 40-fold concentration of paraquat, a pesticide commonly present in the commercial formulations of diquat.

Supramolecular host-guest chemistry is a topic of great current interest. However, the further development of host-guest chemistry is still limited by the number of available host-guest recognition motifs. This makes it necessary and valuable to find new host-guest recognition motifs and apply known host-guest recognition motifs in the preparation of novel supramolecular systems. By comparing the crystal structures of the host and its taco complex, we proved that folding is a necessary step during the formation of taco complexes. Based on the known bis(m-phenylene)-32-crown-10/paraquat recognition motif, the first solid-state supramolecular poly(taco complex) was prepared. We demonstrate not only that bis(m-phenylene)-32-crown-10-based cryptands are powerful hosts for paraquat derivatives compared with the simple crown ether, but also that cooperative complexation can be obtained with the cryptand structure. It was shown that the significant improvement in complexation was the result of the combination of the preorganization of the cryptand hosts and the introduction of additional and optimized binding sites. Furthermore, it was demonstrated that improved complexation of bis(secondary ammonium) and bisparaquat salts could also be achieved by the formation of the pseudocryptand structure. We also prepared two dimers of inclusion cryptand/paraquat complexes driven by dipole-dipole and face-to-face p-stacking interactions. An interesting complex based on dibenzo-24-crown-10 and diquat was prepared. In its crystal structure the diquat guest lies in the concave cavity provided by two dibenzo-24-crown-8 hosts. Monopyridinium-based [2]- and [3]-pseudorotaxanes were prepared based on the newly discovered bis(m-phenylene)-32-crown-10/monopyridinium salt and cryptand/monopyridinium salt recognition motifs. Inspired by the formation of solid-state taco complexes between bis(m-phenylene)-32-crown-10 and paraquat derivatives, we designed and synthesized the first cylindrical bis

Phytophthora infestans (Mont) de Bary is a devastating pathogen in potato producing regions around the world. Populations of the organism in Canada shifted during the mid-1990’s as the US-1 strain (A1, metalaxyl-sensitive) was displaced by the highly aggressive, US-8 strain (A2, metalaxyl-insensitive). An increase in the incidence and severity of late blight has followed. Late blight is controlled by cultural practices aimed at eliminating disease sources and by the application of foliar fungicides. Tubers can become infected at harvest from contact with blighted vines leading to severe losses in storage. In many production areas, growers desiccate vines two to three weeks prior to harvest to reduce late blight tuber rot. However, in Manitoba, because of the loss of potential yield that results from vine killing prior to harvest in a late maturing cultivar such as Russet Burbank, growers are reluctant to adopt this practice. The objective of this study was to develop recommendations for preharvest management practices that reduce storage losses due to late blight. Field trials were conducted in 1997 and 1998 to investigate the effect of vine desiccation with diquat and/or a late season application of chlorothalonil and copper hydroxide on yield, processing quality, and disease development in storage. Desiccating vines with diquat two weeks prior to harvest reduced yield and tuber size. Compared to the untreated control, the largest reductions in marketable yield were observed for the early September harvest. By the late September harvest, however, the effect of vine killing in reducing marketable yield was less apparent. Specific gravity was lower in the vine killed treatment for all harvest dates in 1997 and in the early and mid September harvests in 1998. Vine killing did not contribute to elevated levels of reducing sugars or consistently darker fry colour at harvest or during storage. Skin-set was improved when vines were desiccated for all harvest dates in 1997

This small-scale study examined three turbidity levels in the water column to investi- gate the efficacy of diquat (6,7-dihydrodipyridoL,2-ALPHA:2',1'-Cpyrazinediium ion) in combination with the dipotassium salt of endothall (7-oxabicyclo2.2.L heptane-2,3- dicarboxylic acid) to control hydrilla (Hydrilla verticillata (L.f.) Royle).

The invasion of exotic plants such as Eurasian watermilfoil (Myriophyllum spicatum L.) has contributed to the decline and displacement of native wild rice (Zizania aquatica L.) populations in many U.S. water bodies. Wild rice is a popular food source for both man and animal and provides important habitat for waterfowl, invertebrates, and fish. Herbicides can be successfully used to manage invasive weeds such as Eurasian watermilfoil; however, the potential impacts of such chemical management techniques on native plants (including wild rice) are not well documented. This outdoor tank study was conducted to examine the effects of several aquatic herbicides on the growth and survival of wild rice and to determine whether nontarget herbicide efficacy is influenced by wild rice growth stage. Aquatic formulations of the herbicides diquat, endothall, fluridone, and 2,4-D were applied at varying rates and contact times to three growth stages of wild rice. Results showed that degree of herbicide injury varied with plant growth stage. Wild rice treated at younger growth stages (early tillering or seedling stages) was more sensitive to chemical treatment than plants treated at later stages of development. Regardless of product or rate, herbicide treatment did not affect wild rice plants when applied at the mature growth stage (late tillering and flowering). Of the herbicides evaluated, wild rice was most sensitive to 2,4-D. Rates as low as 1 mg 2,4-D L- significantly inhibited tiller, seedhead, and dry weight biomass production in young wild rice. Dry weight of young wild rice was also reduced following exposure to endothall, diquat, and fluridone; however, seedhead and tiller production was not influenced by these products., Prepared in collaboration with Analytical Services, Inc. ,Huntsville, Al.

CASE REPORT: A 37-year-old man ingested in a suicide attempt 300 mL of a diquat solution (equivalent to 60 g diquat ion). The initial diquat serum concentration was 64 microg/mL 4 hours after poisoning. The clinical course was characterized by a progressive anuria and by neurological disorders (coma and seizures). The patient died 26 hours after poisoning from refractory cardiocirculatory collapse. Extracorporeal techniques removed 1.09 g of diquat which could be considered as significant in regard to the total amount that was likely absorbed, but they did not influence the clinical outcome. There was marked renal tubular damage at autopsy and the highest diquat tissue concentration was found in the kidneys.

It has been found that diquat and diquat plus copper can be used effectively to control egeria and hydrilla. Repeat applications are necessary for proper maintenance. Herbicide residues are dissipated in 1-3 days, depending upon the specific situation. Results indicate that no residues are to be found in crops irrigated with water treated with diquat at the levels used for the control of obnoxious aquatic vegetation. Color illustrations reproduced in black and white., See also report dated Nov 75, AD-A018 866.

De resultaten van de literatuurstudie worden samengevat in een overzicht van de bepalingsmetboden van paraquat en diquat in groenten en fruit e.d. Naast de toepassingsgebieden, chemische en fysische eigenschappen van paraquat en diquat werden de bepalingsmethoden bestudeerd. Spektrofotometrische, gaschromatografische en vloeistofchromatografische bepalingsmethoden worden behandeld. Bij de bepaling in groenten, fruit e.d. heeft de spektrafotometrische bepaling veel last van achtergrondabsorpties door plantensubstanties. Bovendien kunnen paraquat en diquat niet afzonderlijk worden bepaald. Bij de gaschromatografische bepaling is een derivatiseringsstap noodzakelijk en deze is dus bewerkelijk. Wel kunnen lage detektiegrenzen worden bereikt. De vloeistofchromatografische bepaling is (nog) niet veel toegepast voor allerlei plantaardige produkten, uitgezonderd marihuana en zonnebloempitten, waarbij op een relatief hoog niveau gemeten wordt (1 à 2 ppm). Met behulp van een andere opwerking en eventueel een andere detektiemethode kan de detektiegrens mogelijk verlaagd worden.

Tato diplomová práce se zaměřuje na polární pesticidy a jejich analýzu v zemědělských komoditách. Jedním z cílů bylo zavedení metody kvantitavního stanovení dikvátu a parakvátu pomocí kapalinové chromatografie s tandemovou hmotnostní spektrometrií. Parametry optimalizace vycházely z doporučení evropských referenčních laboratoří s přihlédnutím k možnostem laboratoře a vhodnosti metody pro rutinní analýzu. Extrakce analytů byla založena na vytřepání do metanolu okyseleného kyselinou mravenčí nebo chlorovodíkovou. Na základě složitosti extraktu bylo následně přistoupeno k čištění extraktu za použití kombinací sorbentu a precipitace s acetonitrilem. Validace metody byla provedena na několika hladinách u vybraných zástupců zemědělských komodit. Součástí práce byl polní pokus, spočívající v aplikaci postřiku na bramborový porost obsahující účinnou látku dikvát. Vzorky ošetřené rostliny zahrnující zelenou část rostliny a bramborové hlízy byly následně podrobeny analýze pro zjištění reziduí dikvátu. Validovaná metoda byla využita ke sledování obsahu dikvátu a parakvátu ve vzorcích krmiv odebraných v rámci úředních kontrol Ústředního kontrolního a zkušebního ústavu z roku 2020. Výslednou metodou bylo možné analyzovat dikvát a parakvát s citlivostí v hodnou ke kontrole maximálních hladin reziduí., This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.

Tato diplomová práce se zaměřuje na polární pesticidy a jejich analýzu v zemědělských komoditách. Jedním z cílů bylo zavedení metody kvantitavního stanovení dikvátu a parakvátu pomocí kapalinové chromatografie s tandemovou hmotnostní spektrometrií. Parametry optimalizace vycházely z doporučení evropských referenčních laboratoří s přihlédnutím k možnostem laboratoře a vhodnosti metody pro rutinní analýzu. Extrakce analytů byla založena na vytřepání do metanolu okyseleného kyselinou mravenčí nebo chlorovodíkovou. Na základě složitosti extraktu bylo následně přistoupeno k čištění extraktu za použití kombinací sorbentu a precipitace s acetonitrilem. Validace metody byla provedena na několika hladinách u vybraných zástupců zemědělských komodit. Součástí práce byl polní pokus, spočívající v aplikaci postřiku na bramborový porost obsahující účinnou látku dikvát. Vzorky ošetřené rostliny zahrnující zelenou část rostliny a bramborové hlízy byly následně podrobeny analýze pro zjištění reziduí dikvátu. Validovaná metoda byla využita ke sledování obsahu dikvátu a parakvátu ve vzorcích krmiv odebraných v rámci úředních kontrol Ústředního kontrolního a zkušebního ústavu z roku 2020. Výslednou metodou bylo možné analyzovat dikvát a parakvát s citlivostí v hodnou ke kontrole maximálních hladin reziduí., This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.

Tato diplomová práce se zaměřuje na polární pesticidy a jejich analýzu v zemědělských komoditách. Jedním z cílů bylo zavedení metody kvantitavního stanovení dikvátu a parakvátu pomocí kapalinové chromatografie s tandemovou hmotnostní spektrometrií. Parametry optimalizace vycházely z doporučení evropských referenčních laboratoří s přihlédnutím k možnostem laboratoře a vhodnosti metody pro rutinní analýzu. Extrakce analytů byla založena na vytřepání do metanolu okyseleného kyselinou mravenčí nebo chlorovodíkovou. Na základě složitosti extraktu bylo následně přistoupeno k čištění extraktu za použití kombinací sorbentu a precipitace s acetonitrilem. Validace metody byla provedena na několika hladinách u vybraných zástupců zemědělských komodit. Součástí práce byl polní pokus, spočívající v aplikaci postřiku na bramborový porost obsahující účinnou látku dikvát. Vzorky ošetřené rostliny zahrnující zelenou část rostliny a bramborové hlízy byly následně podrobeny analýze pro zjištění reziduí dikvátu. Validovaná metoda byla využita ke sledování obsahu dikvátu a parakvátu ve vzorcích krmiv odebraných v rámci úředních kontrol Ústředního kontrolního a zkušebního ústavu z roku 2020. Výslednou metodou bylo možné analyzovat dikvát a parakvát s citlivostí v hodnou ke kontrole maximálních hladin reziduí., This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.

Tato diplomová práce se zaměřuje na polární pesticidy a jejich analýzu v zemědělských komoditách. Jedním z cílů bylo zavedení metody kvantitavního stanovení dikvátu a parakvátu pomocí kapalinové chromatografie s tandemovou hmotnostní spektrometrií. Parametry optimalizace vycházely z doporučení evropských referenčních laboratoří s přihlédnutím k možnostem laboratoře a vhodnosti metody pro rutinní analýzu. Extrakce analytů byla založena na vytřepání do metanolu okyseleného kyselinou mravenčí nebo chlorovodíkovou. Na základě složitosti extraktu bylo následně přistoupeno k čištění extraktu za použití kombinací sorbentu a precipitace s acetonitrilem. Validace metody byla provedena na několika hladinách u vybraných zástupců zemědělských komodit. Součástí práce byl polní pokus, spočívající v aplikaci postřiku na bramborový porost obsahující účinnou látku dikvát. Vzorky ošetřené rostliny zahrnující zelenou část rostliny a bramborové hlízy byly následně podrobeny analýze pro zjištění reziduí dikvátu. Validovaná metoda byla využita ke sledování obsahu dikvátu a parakvátu ve vzorcích krmiv odebraných v rámci úředních kontrol Ústředního kontrolního a zkušebního ústavu z roku 2020. Výslednou metodou bylo možné analyzovat dikvát a parakvát s citlivostí v hodnou ke kontrole maximálních hladin reziduí., This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.

Tato diplomová práce se zaměřuje na polární pesticidy a jejich analýzu v zemědělských komoditách. Jedním z cílů bylo zavedení metody kvantitavního stanovení dikvátu a parakvátu pomocí kapalinové chromatografie s tandemovou hmotnostní spektrometrií. Parametry optimalizace vycházely z doporučení evropských referenčních laboratoří s přihlédnutím k možnostem laboratoře a vhodnosti metody pro rutinní analýzu. Extrakce analytů byla založena na vytřepání do metanolu okyseleného kyselinou mravenčí nebo chlorovodíkovou. Na základě složitosti extraktu bylo následně přistoupeno k čištění extraktu za použití kombinací sorbentu a precipitace s acetonitrilem. Validace metody byla provedena na několika hladinách u vybraných zástupců zemědělských komodit. Součástí práce byl polní pokus, spočívající v aplikaci postřiku na bramborový porost obsahující účinnou látku dikvát. Vzorky ošetřené rostliny zahrnující zelenou část rostliny a bramborové hlízy byly následně podrobeny analýze pro zjištění reziduí dikvátu. Validovaná metoda byla využita ke sledování obsahu dikvátu a parakvátu ve vzorcích krmiv odebraných v rámci úředních kontrol Ústředního kontrolního a zkušebního ústavu z roku 2020. Výslednou metodou bylo možné analyzovat dikvát a parakvát s citlivostí v hodnou ke kontrole maximálních hladin reziduí., This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.

Tato diplomová práce se zaměřuje na polární pesticidy a jejich analýzu v zemědělských komoditách. Jedním z cílů bylo zavedení metody kvantitavního stanovení dikvátu a parakvátu pomocí kapalinové chromatografie s tandemovou hmotnostní spektrometrií. Parametry optimalizace vycházely z doporučení evropských referenčních laboratoří s přihlédnutím k možnostem laboratoře a vhodnosti metody pro rutinní analýzu. Extrakce analytů byla založena na vytřepání do metanolu okyseleného kyselinou mravenčí nebo chlorovodíkovou. Na základě složitosti extraktu bylo následně přistoupeno k čištění extraktu za použití kombinací sorbentu a precipitace s acetonitrilem. Validace metody byla provedena na několika hladinách u vybraných zástupců zemědělských komodit. Součástí práce byl polní pokus, spočívající v aplikaci postřiku na bramborový porost obsahující účinnou látku dikvát. Vzorky ošetřené rostliny zahrnující zelenou část rostliny a bramborové hlízy byly následně podrobeny analýze pro zjištění reziduí dikvátu. Validovaná metoda byla využita ke sledování obsahu dikvátu a parakvátu ve vzorcích krmiv odebraných v rámci úředních kontrol Ústředního kontrolního a zkušebního ústavu z roku 2020. Výslednou metodou bylo možné analyzovat dikvát a parakvát s citlivostí v hodnou ke kontrole maximálních hladin reziduí., This diploma thesis focuses on polar pesticides and their analysis in agricultural commodities. One of the aims was establishing of the method for quantitative determination of diquat and paraquat using liquid chromatography with tandem mass spectrometry. Optimization parameters based on the European reference laboratories recommendations, availability of laboratory equipment and method suitability for routine analyses were taken into account. Extraction of analytes was based on shaking with acidified methanol with formic or hydrochloric acid. Considering the matrix complexity, purification with sorbents and/or acetonitrile precipitation were applied. Method validation was carried out on several levels for selected representative agricultural commodities. Part of the thesis is a field experiment where potatoes plants were sprayed with the diquat active substance. Samples of treated plants and tubers were analyzed for diquat residues. The validated method was also used for screening of diquat and paraquat residues in feed samples collected within official controls of the Central Institute for Supervising and Testing in Agriculture in 2020. The final method enables to analyze diquat and paraquat with sensitivity suitable for the maximal residue limit controls.