Concentration Of Diquat Research Articles

Association between initial diquat plasma concentration, severity index and in-hospital mortality in patients with acute diquat poisoning: a retrospective cohort study

Background Since 2016, diquat has replaced paraquat in China, resulting in increased diquat poisoning cases. However, understanding of diquat poisoning is still limited. This study aimed to investigate the relationship between initial diquat plasma concentration, severity index, and in-hospital mortality in acute diquat poisoning cases. Methods This retrospective cohort study, conducted from January 2016 to July 2023 in a tertiary care hospital, used univariate logistic regression to examine the link between the initial diquat plasma concentration, severity index, and in-hospital mortality in acute diquat poisoned patients. A receiver operating characteristic curve assessed the predictive value of these parameters for prognosis. Results Among the 87 participants, the median age was 32 years, 35 (40.2%) were female. The overall mortality rate was 37.9%. Logistic regression analysis revealed that the initial diquat plasma concentration and severity index were associated with increased in-hospital mortality. These factors also effectively predicted the prognosis of acute diquat poisoning, with an area under the receiver operating characteristic curve of 0.851 and an optimal diquat concentration threshold of 2.25 mg/L (sensitivity 90.9%, specificity 74.1%, P < 0.05) and an area under the receiver operating characteristic curve of 0.845 with an optimal cut-off value for the sevity index of 9.1 mg/L*min (sensitivity 97%, specificity 74.1%, P < 0.05). Discussion Our results are limited by the retrospective design of this study. However, if validated, these results could impact management strategies, especially in East Asia. Further research is needed due to potential confounding factors. Conclusions The findings suggest that a higher initial plasma concentration and severity index in patients with acute diquat poisoning were correlated with higher in-hospital mortality. Prospective validation will confirm the predicative value of these findings.

Portable Copper-Based Electrochemical SERS Sensor for Point-of-Care Testing of Paraquat and Diquat by On-Site Electrostatic Preconcentration.

With the advent of portable Raman spectrometers, the deployment of surface-enhanced Raman spectroscopy (SERS) in point-of-care testing (POCT) has been initiated. Within any analytical framework employing SERS, the acuity and selectivity inherent to the SERS substrate are of paramount importance. In this article, we utilize in situ electrochemical passivation technology to fabricate CuI passivation film, which serves as a flexible copper-based SERS substrate. Furthermore, portable electrochemical SERS (EC-SERS) sensors were prepared by combining this with laser direct writing technology. The detection signal was amplified using electrostatic preconcentration technology, showcasing impressive sensitivity, selectivity, and stability in pesticide detection. The detected concentrations of paraquat and diquat in tea reached as low as 3.36 and 2.43 μg/kg, respectively. Furthermore, the application of electrostatic preconcentration facilitated selective target molecule aggregation on the SERS sensor, markedly increasing Raman signal strength and enabling single-molecule detection. This research introduces an innovative POCT method for pesticides, promising to advance environmental monitoring's analytical capabilities.

Prognostic value of plasma diquat concentration in patients with acute oral diquat poisoning: a retrospective study.

Diquat poisoning is an important public health and social security agency. This study aimed to develop a prognostic model and evaluate the prognostic value of plasma diquat concentration in patients with acute oral diquat poisoning, focusing on how its impact changes over time after poisoning. This was a retrospective cohort study using electronic healthcare reports from the Second Hospital of Hebei Medical University. The study sample included 80 patients with acute oral Diquat poisoning who were admitted to the hospital between January 2019 and May 2022. Time-to-event analyses were performed to assess the risk of all-cause mortality (30 days and 90 days), controlling for demographics, comorbidities, vital signs, and other laboratory measurements. The prognostic value of plasma DQ concentration on admission was assessed by computing the area under a time-dependent receiver operating characteristic curve (ROC). Among the 80 patients, 29 (36.25%) patients died, and 51 (63.75%) patients survived in the hospital. Non-survivors had a median survival time (IQR) of 1.3(1.0) days and the longest survival time of 4.5 days after DQ poisoning. Compared with non-survivors, survivors had significantly lower amounts of ingestion, plasma DQ concentration on admission, lungs injury within 24 h after admission, liver injury within 24 h after admission, kidney injury within 24 h after admission, and CNS injury within 36 h after admission, higher APACHE II score and PSS within 24 h after admission (all p < 0.05). Plasma Diquat concentration at admission (HR = Exp (0.032-0.059 × ln (t))) and PSS within 24 h after admission (HR: 4.470, 95%CI: 1.604 ~ 12.452, p = 0.004) were independent prognostic factors in the time-dependent Cox regression model. Plasma DQ concentration at admission and PSS within 24 h after admission are independent prognostic factors for the in-hospital case fatality rate in patients with acute oral DQ poisoning. The prognostic value of plasma DQ concentration decreased with time.

Nutrient release dynamics in relation to stages of Lagarosiphon major decay following treatment with diquat herbicide

Herbicide treated weed beds release nutrients into the water column and have been implicated in providing ‘fuel’ for algal blooms. Here we assess the timing and magnitude of nutrient releases in relation to the visual signs of plant damage post-herbicide treatment. Lagarosiphon major shoots were exposed to one of eleven different diquat concentrations ranging from 0 to 1 mg l−1 for 1, 10 or 100 min. Visual symptom of decay and total nitrogen (TN) and phosphorus (TP) concentration were monitored for 21 days after treatment. The largest rate and amount of TN and TP were released prior to and with shoot discolouration, suggesting a mechanism of diquat mediated cell lysis. Proportionally more P than N was released initially, and P releases became negative as the lagarosiphon decayed. N releases peaked with shoot discolouration, declining for the remainder of the assessment period, becoming negative when the shoot was deemed dead. The relationship between visual stage of decay and TN and TP release identified in this study could be used by lake managers to help assess the role of herbicide treated weed beds in fuelling algal blooms but will need to be put into a lake specific framework.

Efficacy and rates of diquat for reducing invasive knotweeds and potential for sequential use with imazapyr

AbstractInvasive knotweeds (Reynoutria spp.) pose an ongoing challenge for weed management programs worldwide, requiring years of persistent treatment. In this study, we tested efficacy of diquat applied as foliar spray early in the growing season for short‐term suppression, and for potential to boost long‐term control when applied sequentially with a mid‐season treatment of imazapyr. We evaluated responses of knotweeds (R. japonica, R. × bohemica, and R. sachelinensis) treated with one of three diquat concentrations (0.25%, 0.50%, or 1.0%, v/v), using multiple metrics to capture changes in aboveground plant density and abundance. Canopy cover and biomass were significantly reduced by all diquat concentrations and resembled pre‐treatment conditions at 8WAT, reflecting the shift toward reduced stem heights in treated compared with untreated plots. Stem counts at 8WAT, however, did not differ in response to diquat treatments. Sequentially applied early‐season diquat and mid‐season imazapyr treatments reduced canopy cover (66%–82%), biomass (65%–91%), and stem density (57%–79%) when evaluated 1 year after treatment; reductions were greatest in plots treated with medium and high diquat concentrations, suggesting that diquat treatments may have an additive effect. Overall, our study establishes rates of diquat to reduce biomass of invasive knotweed, and supports additional testing to assess improvement in long‐term control when used sequentially with a systemic herbicide.

Rapid and highly sensitive determination of unexpected diquat and paraquat in biological fluids by electro-enhanced SPME-SERS

Poisoning with diquat (DQ) and paraquat (PQ) herbicides has been a public health problem. Unfortunately, rapid detection in biofluids remains challenging. Herein, a hyphenated approach of electro-enhanced adsorption, solid-phase microextraction, and surface-enhanced Raman spectroscopy (EE−SPME−SERS) was exploited for rapid and sensitive in situ analysis of DQ and PQ in human urine and plasma. A porous Ag fiber with an Au layer (p-Ag/Au fiber) was fabricated with multi-functions (SERS substrate, SPME sorbent, and working electrode). Clear trends could be observed between signal intensity and concentration of DQ or PQ with high reproducibility. The method detection limits (MDLs) calculated from the characteristic peak of DQ were 0.064 ppb and 0.65 ppb in urine and plasma, respectively. Corresponding MDLs for DQ and PQ in urine and plasma were 0.036 ppb and 0.35 ppb, respectively. The whole process of “extracting and detecting” was completed within 4 min with satisfactory recoveries. Notably, the EE−SPME−SERS technique could easily realize in situ analysis of DQ and PQ in biofluids with good selectivity, which is practical in clinical diagnosis. This EE−SPME−SERS method provides a potential avenue for efficient pretreatment and in situ poison detection in biological samples.

Case report: Successful outcome of a young patient with rhabdomyolysis and shock caused by diquat poisoning.

The widespread use of diquat as a substitute for paraquat has led to an increase in poisoning deaths. A successful case of diquat poisoning complicated with rhabdomyolysis and shock was lacking. A 13-year-old previously healthy girl ingested 40 ml of diquat solution in a suicide attempt. The concentration of diquat in serum was 436.2 ug/L at 10 h after poisoning. The clinical course was characterized by progressive multi-organ dysfunction, particularly rhabdomyolysis and shock. The main treatments included intensive hemoperfusion combined with continuous renal replacement therapy (CRRT), drainage, and activated carbon adsorption. Meanwhile, accurate dilatation under the model of pulse indicator continuous cardiac output (PICCO) was essential for the successful treatment of shock. The serum concentration of diquat declined to 20 ug/L after 96 h of treatments. The patient was discharged from the hospital after 3 weeks of treatment without obvious symptoms. So far, this was the first successful case of diquat poisoning complicated with rhabdomyolysis and shock, which would enrich the experience of diquat poisoning treatment.

Paraquat and Diquat: Recent Updates on Their Pretreatment and Analysis Methods since 2010 in Biological Samples.

Paraquat (PQ) and diquat (DQ) are quaternary ammonium herbicides which have been used worldwide for controlling the growth of weeds on land and in water. However, PQ and DQ are well known to be toxic. PQ is especially toxic to humans. Moreover, there is no specific antidote for PQ poisoning. The main treatment for PQ poisoning is hemoperfusion to reduce the PQ concentration in blood. Therefore, it is essential to be able to detect PQ and DQ concentrations in biological samples. This critical review summarizes the articles published from 2010 to 2022 and can help researchers to understand the development of the sample treatment and analytical methods for the determination of PQ and DQ in various types of biological samples. The sample preparation includes liquid-liquid extraction, solid-phase extraction based on different novel materials, microextration methods, and other methods. Analytical methods for quantifying PQ and DQ, such as different chromatography and spectroscopy methods, electrochemical methods, and immunological methods, are illustrated and compared. We focus on the latest advances in PQ and DQ treatment and the application of new technologies for these analyses. In our opinion, tandem mass spectrometry is a good choice for the determination of PQ and DQ, due to its high sensitivity, high selectivity, and high accuracy. As far as we are concerned, the best LOD of 4 pg/mL for PQ in serum can be obtained.

Diquat Poisoning: Care Management and Medico-Legal Implications.

Acute chemical intoxication represents one of the major causes of Emergency Room admittance, and possible errors in diagnosis are extremely frequent, especially when patients present generic and non-specific symptoms. Diquat, a bipyridyl class of herbicides, exerts high intrinsic toxicity as a consequence of free oxygen radicals, leading to cellular death and organ dysfunctions. Following ingestion, with the major source of absorption for suicidal purposes, the chemical induces local irritating effects; systemic symptoms appear later, while specific symptoms can occur in the following 48 h. A smoker and hypertensive 50-year-old man arrives at the E.R., reporting that an episode of herbicide inhalation occurred few hours earlier. Physical examination evidenced alkalosis with hypoxemia, leucocytosis, mild hyperglycaemia and moderate increase in creatine kinase and myoglobin. Despite blood creatine kinase and myoglobin values that were higher than normal, he was prescribed with hydration and anti-pain therapy. During the night, the man left the hospital; he returned the next morning at 8:45 a.m., with cardiorespiratory arrest, medium fixed non-reactive mydriasis, diffused cyanosis of the skin and of the mucous membranes, as well as imperceptible pulse and peripheral pressure. Despite resuscitation attempts, the patient died at 9:30 a.m.; the body was immediately transferred to the morgue. Autopsy and toxicological analyses were carried out nine days later, evidencing paraquat ingestion for suicidal purposes. GC/MS analyses to verify the presence of diquat were performed on body fluids and gastric and colon contents; all specimens resulted positive, thus confirming the cause of death as herbicide ingestion (blood diquat concentration of 1.2 mg/L; more than twice the minimum to observe a systemic poisoning). The procedure followed for patient management resulted to be not in line with the provisions of both guidelines and good clinical practices. Staff did not perform clinical-diagnostical monitoring of the patient’s condition or ask for more specific analyses (i.e., serum creatine phosphokinase monitoring). This misconduct led to a decrease in the patient’s chances to survive.

Kidney and lung injury in rats following acute diquat exposure.

Diquat (1,1'-ethylene-2,2'-bipyridylium) is a type of widely used agricultural chemical, whose toxicity results in damage to numerous tissues, including the lung, liver, kidney and brain. The aim of the present study was to establish a rat model of acute diquat exposure and explore the relationship between diquat concentration, and kidney and lung injury, in order to provide an experimental basis for clinical treatment. A total of 140 healthy adult male Wistar rats were randomly divided into control and exposure groups. The diquat solution was administered intragastrically to the exposure group at 1/2 of the lethal dose (140 mg/kg). An equal volume of water was administered to the control group. The dynamic changes in the plasma and tissue diquat levels were quantitatively determined at 0.5, 1, 2, 4, 8, 16 and 24 h following exposure using liquid chromatography mass spectrometry. The content of hydroxyproline (HYP) in the lung tissues, as well as the levels of blood urea nitrogen (BUN), creatinine (Cr), uric acid (UA), kidney injury molecule-1 (KIM-1) and tumor growth factor (TGF)-β1, were detected using western blot analysis at every time point. Lung and kidney morphology were also assessed. Electron microscopy showed that the degree of renal damage gradually increased with time. Vacuolation gradually increased, some mitochondrial bilayer membrane structures disappeared and lysosomes increased. The lung tissue damage was mild, and the cell membrane integrity and organelles were damaged to varying degrees. The plasma and organ levels of diquat peaked at ~2 h, followed by a steady decrease, depending on the excretion rate. Over time, the serum concentrations of UA, BUN, Cr and KIM-1 were all significantly increased (P<0.05). Serum KIM-1 in rats was increased after 0.5 h, and was significantly increased after 4 h, suggesting that KIM-1 is an effective predictor of early renal injury. Early TGF-β1 expression was clearly observed in renal tissue, while no clear TGF-β1 expression was observed in the lung tissue. In conclusion, the concentration of diquat in the serum and tissue of rats with acute diquat poisoning peaked at an early stage and then rapidly decreased. The renal function damage and pathological changes persisted, the lung tissue was slightly damaged with inflammatory cell infiltration, and early pulmonary fibrosis injury was not obvious.

Feed Composition Differences Resulting from Organic and Conventional Farming Practices Affect Physiological Parameters in Wistar Rats-Results from a Factorial, Two-Generation Dietary Intervention Trial.

Recent human cohort studies reported positive associations between organic food consumption and a lower incidence of obesity, cancer, and several other diseases. However, there are very few animal and human dietary intervention studies that provide supporting evidence or a mechanistic understanding of these associations. Here we report results from a two-generation, dietary intervention study with male Wistar rats to identify the effects of feeds made from organic and conventional crops on growth, hormonal, and immune system parameters that are known to affect the risk of a number of chronic, non-communicable diseases in animals and humans. A 2 × 2 factorial design was used to separate the effects of contrasting crop protection methods (use or non-use of synthetic chemical pesticides) and fertilizers (mineral nitrogen, phosphorus and potassium (NPK) fertilizers vs. manure use) applied in conventional and organic crop production. Conventional, pesticide-based crop protection resulted in significantly lower fiber, polyphenol, flavonoid, and lutein, but higher lipid, aldicarb, and diquat concentrations in animal feeds. Conventional, mineral NPK-based fertilization resulted in significantly lower polyphenol, but higher cadmium and protein concentrations in feeds. Feed composition differences resulting from the use of pesticides and/or mineral NPK-fertilizer had a significant effect on feed intake, weight gain, plasma hormone, and immunoglobulin concentrations, and lymphocyte proliferation in both generations of rats and in the second generation also on the body weight at weaning. Results suggest that relatively small changes in dietary intakes of (a) protein, lipids, and fiber, (b) toxic and/or endocrine-disrupting pesticides and metals, and (c) polyphenols and other antioxidants (resulting from pesticide and/or mineral NPK-fertilizer use) had complex and often interactive effects on endocrine, immune systems and growth parameters in rats. However, the physiological responses to contrasting feed composition/intake profiles differed substantially between the first and second generations of rats. This may indicate epigenetic programming and/or the generation of “adaptive” phenotypes and should be investigated further.

Simultaneous determination of paraquat and diquat in plasma and urine by ion chromatography-triple quadrupole mass spectrometry

Paraquat (PQ) and diquat (DQ) are widely used as non-selective contact herbicides. Several cases involving accidents, suicide, and homicide by PQ or DQ poisoning have been reported. Poising by PQ, which is mainly concentrated in the lungs, causes acute respiratory distress syndrome and leads to multiple organ toxicity. The toxic effects of DQ are similar to those of PQ but relatively less intense. The mortality rates in PQ and DQ poisoning are high. Simultaneous monitoring of the PQ and DQ concentrations in plasma and urine can provide valuable information for early clinical diagnosis and prognosis. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) is the main analytical method used to detect PQ and DQ in plasma and urine. As both these compounds are highly polar and water soluble, they cannot be retained effectively on a reversed-phase column with conventional mobile phases. The separation of PQ and DQ by ion-pair chromatography or hydrophilic chromatography has been reported. The use of an ion-pairing reagent helps in improving the retention capabilities of PQ and DQ. However, the sensitivity of MS detection is noticeably decreased because of ion suppression caused by the ion-pairing reagent in the mobile phase; furthermore, ion-pairing reagents may contaminate the MS system. The separation of PQ and DQ by hydrophilic chromatography is easily affected by matrix components in the sample, and their retention times are not stable. Considering PQ and DQ are bicharged cation species in solution, they are more suitable for separation by cation-exchange chromatography. A method based on ion chromatography-triple quadrupole mass spectrometry was established for the determination of PQ and DQ in plasma and urine. The plasma and urine samples were diluted with water, and then purified on a solid-phase extraction column containing a polymer-reversed phase and weak ion-exchange mixed-mode adsorbent (Oasis WCX). PQ and DQ were separated on an IonPac CS 18 analytical column (250 mm×2.0 mm, 6.0 μm) with gradient elution using a methylsulfonic acid solution electrolytically generated from an on-line eluent generation cartridge. An in-line suppressor was used to remove methylsulfonate and other anions from the eluent before the eluent entered the mass spectrometer. Between the suppressor and the ion source in MS, the addition of 3% (v/v) formic acid in acetonitrile as an organic modifier (using an auxiliary pump and a T-piece) aided desolvation in the ion source, resulted in a one-or two-fold improvement of the response, and eliminated the residual effects of the adsorption of PQ and DQ caused by ion source. The analytes were detected by triple quadrupole tandem mass spectrometry using positive electrospray ionization in the multiple reaction monitoring (MRM) mode. PQ-d8 and DQ-d4 were used as internal standards. The calibration curves for PQ and DQ showed good linear relationships in the ranges of 1.0-150 μg/L and 0.5-75 μg/L, respectively, and the correlation coefficients were > 0.999. The average matrix effects of PQ and DQ in plasma were 84.2%-89.3% and 84.7%-91.1%, while the average matrix effects of PQ and DQ in urine were 50.3%-58.4% and 51.9%-59.4%. The average recoveries of PQ and DQ in plasma were 93.5%-117% and 91.7%-112%, respectively, with relative standard deviations (RSDs) of 3.4-16.7% and 2.8%-13.2%, and that in urine were 90.0%-118% and 99.2%-116%, with relative standard deviations of 5.6%-14.9% and 2.4%-17.3% (n=6). The limits of detection of PQ and DQ in plasma and urine were 0.3 μg/L and 0.2 μg/L, respectively, with the corresponding limits of quantification being 1.0 μg/L and 0.5 μg/L. This method is sensitive and accurate, and it can be used to determine PQ and DQ for clinical diagnosis and prognosis in patients.

Simultaneous determination of paraquat and diquat in human plasma by HPLC-DAD: Its application in acute poisoning patients induced by these two herbicides.

BackgroundParaquat and diquat are widely used in agricultural production in many countries, which are very toxic to human beings. Paraquat can be detected in some diquat solution sold in the market. The blood concentration of paraquat or diquat is an important indicator for clinical diagnosis of paraquat or diquat poisoning. So, it is very meaningful to develop a method for simultaneous determination of paraquat and diquat in human plasma.ObjectiveTo develop and validate a HPLC‐DAD method for simultaneous determination of paraquat and diquat in human plasma and to apply it in the acute poisoning patients by these two herbicides.MethodsParaquat and diquat were simultaneously determined by HPLC‐DAD. The plasma was treated using Waters OASIS® Column and then separated on a Thermo Hypersil GOLD (250 × 4.6 mm, 5 μm) Column with the mobile phase consisted of 75 mmol/L sodium heptane sulfonate (containing 0.1 mol/L phosphoric acid, pH 3.0) and acetonitrile (87:13, v:v) at a flow rate of 1.0 mL/min. The full‐wavelength scanning was 200‐400 nm, and the detection wavelength of paraquat and diquat was 257nm and 310nm, respectively. 120 and 30 plasma samples from patients with paraquat and diquat poisoning were collected and analyzed by the established method.ResultsThe standard curve for paraquat and diquat ranged from 0.05 to 20 μg/mL, and the precision of LLOQ for paraquat was 16.49%, which was required to be less than 20%. The precision of other concentrations was less than 14.14%. The recovery of paraquat and diquat was 95.38%‐103.97% and 94.79%‐98.40%, respectively. The results showed that paraquat and diquat were stable under various storage conditions. 120 plasma samples of paraquat poisoning patients and 30 plasma samples of diquat poisoning patients were determined by the established method. The blood concentration of paraquat ranged from 0.10 to 20.62 μg/mL, with an average of 3.61 μg/mL, while for diquat, the concentration ranged from 0 to 26.59 μg/mL, with an average of 2.00 μg/mL. Among the diquat suspected poisoning samples, 5 samples were detected not only diquat but also paraquat, and 2 samples were detected only paraquat, no diquat.ConclusionThe HPLC‐DAD method established in this study was high throughput, high sensitivity, simple operation, and wide linear ranges. It can be used for the screening analysis and quantitative detection of paraquat and diquat in acute poisoning patients, which can provide basis for the treatment and prognosis of these two herbicides poisoning patients.

The expression of Nrf2 in the lung tissue of rats with acute diquat poisoning and the distribution of diquat in lungs

Objective: To investigate the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) in the lung tissue of rats with acute diquat (DQ) poisoning and the distribution of diquat in lungs. Methods: Fifty-four fasted male Wistar rats were randomized into control group (n=6) and exposure group (n=48) . According to the time point, the exposure group was divided into 2 h, 4 h, 12 h, 1 d, 3 d, 7 d, 11 d and 14 d groups with 6 rats in each group. Exposure groups were administered 11.55 mg/kg DQ (1 ml/100 g BW) by single-dose of intragastric administration, while the control group rats were given normal saline. The histopathological changes of lung tissue of rats in each group were observed. The expression of nrf2 in lung tissue was detected by immunohistochemistry, and the diquat concentration in lungs was determined by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS) . Results: In the exposure group, DQ was detected in lungs on 2 hours after poisoning. The concentration of DQ in lung tissue decreased gradually over time, and there was no accumulation in lung tissue. The histopathological changes of lung tissue were not obvious in the early stage of poisoning. The injury was the most serious on the 3rd day, a large number of inflammatory cells could be seen in alveolar cavity and lung stroma, and the pathological injury of lung tissue began to be alleviated on the 7th day. The results of immunohistochemistry showed that Nrf2 was mainly expressed in the nucleus of pulmonery cells. The expression of Nrf2 in the exposure group was significantly higher than the control group. The expression of Nrf2 increased significantly at the 12th hour (P<0.05) , reached the peak on the 3rd day (P<0.05) . There was no difference between the control group and the 14th day (P>0.05) . Conclusion: There was no accumulation of DQ in the lung tissue for a long time, and there was a hysteresis in lung injury induced by redox reaction of DQ. Nrf2 was highly expressed in the lung tissue of rats with acute DQ poisoning, which was correlated with histopathology injury of lung tissue, suggesting that Nrf2 plays an important role in antagonizing acute lung injury induced by DQ.

The experimental study of diquat on the half-Lethal dose and pothological injuny of related organs in wistor rats

Objective: To explore the acute toxicity of Diquat in mice and to calculate the median lethal dose (LD(50)) of Diquat to rats and observe the pathological changes of tissues and organs in rats with different concentrations of Diquat. Methods: Diquat solution of 50 mg/kg was prepared freshly with 1 000 mg of Diquat and dilute the solution with water to a total of 20 ml. A total of 99 healthy adult male Wistar rats were randomly divided into part one, part two and control groups. In the first part, 36 rats were randomly divided into 4 groups: 100 mg/kg group, 200 mg/kg group, 300 mg/kg group and 400 mg/kg group, which were treated with 100 mg/kg, 200 mg/kg, 300 mg/kg and 400 mg/kg of Diquat solution by gavage, respectively. The death and symptoms of poisoning after intragastric administration were recorded, and the maximum tolerated dose and absolute lethal dose were measured. In the second part, 54 rats were randomly divided into 6 groups: 200 mg/kg group, 220 mg/kg group, 240 mg/kg group, 260 mg/kg、280 mg/kg group and 300 mg/kg group, whichwere treated with 200 mg/kg, 220 mg/kg, 240 mg/kg, 260 mg/kg, 280 mg/kg and 300 mg/kg of Diquat solution by gavage, respectively. The survival of rats in different concentration of Diquat was observed and the LD(50) was calculated by Excel processing the formula of Koch's method. The control group were given equal volume water under the same experimental conditions. And moreover, the lungs, kidneys, hearts, livers, and brain tissues were collected and fixed by formaldehyde, embedded by paraffin, and sectioned for histopathological light microscopy. Results: The maximum tolerated dose was 240 mg/kg and the absolute lethal dose was 300 mg/kg. The LD(50) of Diquat for Rats was 280.58 mg/kg. The high-dose group had significantly more organ damage than the low-dose group after diquat poisoning. Conclusion: The determination of the half-lethal dose of diquat, at the same time observed multiple organs damaged in rats after the diquat quickly poisoned. Kidneys, lungs and heart might be the main organ which was heavily damaged. With the extension of observation time, the organ damage of rats exposed to small doses gradually stabilized.

EFFECTIVENESS OF DIQUAT, BOTH ISOLATED AND ASSOCIATED WITH COPPER SOURCES IN CONTROLLING THE Hydrilla verticillata SUBMERGED MACROPHYTES AND ANKISTRODESMUS Gracilis microphyte

ABSTRACT The goal of this study was to evaluate the effectiveness of diquat, both isolated and associated with copper sources (oxychloride and hydroxide) in controling the H. verticillata submerged macrophyte and the A. gracilis microalgae. For this purpose, 10.0 cm H. verticillata young branches and 300 mL of A. gracilis culture were used. The experiments were performed in laboratory and the tested diquat concentrations were: 0.1; 0.2; 0.4; 0.8; 1.2; and 1.8 mg L-1, either isolated or added with 1.0% copper oxychlorideand hydroxide, as well as a control sample. On day 3, 7, 11, 21 and 30 after application, phytotoxicity signs were evaluated and on day 60 after application, green and dry biomass production and plant length were measured. To obtain dry mass, plants remained in a greenhouse with forced air circulation at 65.0 oC, until constant weight. On day 1, 7, 15, 21, 30, 45 and 60 after application, the concentration of chlorophyll a in the water was assessed. The herbicide diquat used alone or in combination with sources copper oxychloride and hydroxide was effective in the control of H. verticillata and microalgae A. gracilis.

Application Volumes and Sizes of Droplets for the Application of Diquat Herbicide in the Control of Eichhornia crassipes

The objective of this study was to evaluate the efficiency of application and the efficacy of control of water hyacinth (Eichhornia crassipes) with the use of the diquat herbicide done with two application volumes associated to three droplets classes. Three experiments were conducted; in the first, the application efficiency was evaluated; in the second, the control efficiency and; in the third, the droplet spectrum. They were conducted in a completely randomized design with five, four and six replicates, respectively. The treatments were arranged in a 2 x 3 factorial design, with two application volumes (100 and 200 L ha-1) and three droplets classes (fine, extremely coarse and ultra-coarse) to the first and second experiment and the third comprised two diquat concentrations in spray solution (2 and 4 g i.a. L-1) and three droplets classes (fine, extremely coarse and ultra-coarse). The application efficiency was determined by the coverage by droplets, spray deposition and active ingredient of the herbicide (diquat). The efficacy was measured by the control and the percentage of plants with regrowth at 50 days after application. The spectrum of droplets produced per each nozzle model used to obtain the droplets classes were analyzed. According to the parameters analyzed, using the droplets classes extremely thick and ultra thick can provide greater certainty in the application of diquat in the aquatic environment associated with the deposition of the active and sufficient coverage to control Eichhornia crassipes with both application volumes

Kinetics and thermodynamics of diquat removal from water using magnetic graphene oxide nanocomposite

A graphene oxide nanocomposite (GO‐Fe3O4) was synthesized with a simple and low‐cost method. This nanocomposite was characterized by XRD, TEM, FT‐IR, TGA, and VSM. Spherical Fe3O4 nanoparticles with an average size of 10 nm were uniformly applied to the surface of graphene oxide sheets. GO‐Fe3O4 nanocomposite showed a superparamagnetic characteristic at room temperature and its saturation magnetization was 8.5 A · M2/kg. The adsorption behaviour of diquat at the surface of GO‐Fe3O4 was investigated, including effects of pH, temperature, and water matrix. The adsorption kinetics, thermodynamics, and adsorption isotherm were also examined. The adsorption was strongly dependent on pH. The adsorption process obeyed the pseudo‐second order kinetic model, and the rate‐determining step might be chemical sorption. The Langmuir adsorption isotherm model was applicable for describing the adsorption of diquat onto GO‐Fe3O4, and the adsorption capacity was 74.85 mg/g at room temperature. Thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic. Most importantly, the GO‐Fe3O4 could remove 96.6 % of diquat from a real water sample when the concentration of diquat is 20 mg/L.

Sunlight induced photocatalytic degradation of herbicide diquat in water in presence of ZnO

Solar photocatalytic degradation of very small amounts of the pollutant herbicide diquat in water in presence of ZnO catalyst is investigated. ZnO is found to be an effective photocatalyst for the decontamination of water in presence of sunlight thus indicating its potential for achieving the twin objectives of solar energy harvesting and wastewater treatment. The influence of various parameters such as catalyst dosage, initial concentration of diquat, pH, O2 and H2O2 on the rate of degradation is investigated and optimised. The degradation follows pseudo first order kinetics. Externally added H2O2 inhibits the degradation initially though the effect becomes less significant as the reaction progresses. The degradation is slow in deaerated reaction systems and extra O2 introduced into it externally enhances the degradation. The study clearly shows that solar photocatalysis using ZnO as the catalyst can be used as an effective tool for the tertiary treatment of diquat contaminated water and the pollutant gets completely mineralised in the process.

Ultra-trace level determination of diquat and paraquat residues in surface and drinking water using ion-pair liquid chromatography with tandem mass spectrometry: a comparison of direct injection and solid-phase extraction methods.

Direct injection and solid-phase extraction methods for the determination of diquat and paraquat in surface and drinking water were developed using liquid chromatography with tandem mass spectrometry. The signal intensities of analytes based on six ion-pairing reagents were compared with each other, and 12.5 mM nonafluoropentanoic acid was selected as the best suited amongst them. A clean-up method was developed using Oasis hydrophilic-lipophilic balance; this was compared to the direct injection method, with respect to limits of detection, interference, precision, and accuracy. Limits of quantification of diquat and paraquat were 0.03 and 0.01μg/L using the direct injection method, and 0.002 and 0.001 μg/L using the hydrophilic-lipophilic balance method. When the hydrophilic-lipophilic balance method was used to analyze target compounds in 114 surface water and 30 drinking water samples, paraquat and diquat were detected within a concentration range of 0.001-0.12 and 0.002-0.038μg/L in surface water, respectively. When the direct injection method was used to analyze target compounds in the same samples, the detected concentrations of paraquat and diquat were within 25% in samples being >0.015 μg/L using the hydrophilic-lipophilic balance method. The liquid chromatography with tandem mass spectrometry method using direct injection can thus be used for routine monitoring of paraquat and diquat in surface and drinking water.