Utilization of N-bromosuccinimide for the sensitive spectrophotometric determination of pipazethate HCl as antitussive drug in pure and dosage forms.

OBJECTIVES: Three simple, sensitive, precise, reproducible and validated spectrophotometric methods have been developed for the quantification of pipazethate HCl as antitussive drug in pure and dosage forms. METHODS: The methods are based on utilization of N-bromosuccinimide as an oxidant and three dyes, amaranth, methylene blue, and indigo carmine, as auxiliary reagents. The proposed methods are based on oxidation reaction of pipazethate HCl with a known excess of N-bromosuccinimide in acid medium, followed by determination of unreacted N-bromosuccinimide by the reaction with a fixed amount of dyes, amaranth, methylene blue, and indigo carmine followed by the measurement of the absorbance at 520, 663 and 610nm, respectively. The optimization of the reaction conditions was investigated. RESULTS: Under the optimum conditions, linear relationships with good correlation coefficients (0.9998-0.9999) were found over the concentration ranges of 0.3-9.0, 0.5-12 and 0.5-10µgmL-1 with a limit of detection (LOD) of 0.1, 0.15 and 0.15µgmL-1 using amaranth, methylene blue, and indigo carmine methods, respectively. Intra-day and inter-day accuracy and precision of the methods have been evaluated. No interference was observed from the common tablet excipients. CONCLUSION: The developed methods were validated in accordance with ICH guidelines and successfully applied to the analysis of pipazethate HCl in dosage forms with good accuracy and precision. The reliability of the methods was further ascertained by performing recovery studies via the standard addition method. Statistical comparison of the results obtained by applying the proposed methods with those of the reported method by applying Student's t-test and variance ratio F-test at the 95% confidence level revealed good agreement and indicates no significant difference in accuracy and precision.

Dissipation of mecoprop-P, isoproturon, bentazon and S-metolachlor in heavy metal contaminated acidic and calcareous soil before and after EDTA-based remediation.

The ability of contaminated farmland soils reclaimed by remediation to dissipate pesticides and thus to mitigate their unwanted environmental effects, i.e., leaching and run-off, was studied. Novel EDTA-based soil washing technology (EDTA and process waters recycling; no toxic emissions) removed 79 and 73% of Pb from acidic and calcareous soil with 740 and 2179 mg kg-1 Pb, respectively. The dissipation kinetics of four herbicides: mecoprop-P, isoproturon, bentazon and S-metolachlor was investigated under field conditions in beds with maize (Zea mays) and barley (Hordeum vulgare). The biphasic First-Order Multi-Compartment (FOMC) model was used to fit experimental data and calculate the herbicides' half-life (DT50) in soil. Remediation significantly (up to 64%) decreased dehydrogenase activity assessed as a marker of soil microbial activity and prolonged the DT50 of herbicides in acidic soils from 16% (isoproturon) to 111% (S-metachlor). Remediation had a less significant effect on herbicide dissipation in calcareous soils; i.e., mecoprop-P DT50 increased by 3%, while isoproturon and S-metachlor DT50 decreased by 29%. Overall, the dissipation from remediated soils was faster than the average DT50 of tested herbicides published in the Pesticides Properties DataBase. Results demonstrate that EDTA-based remediation of the studied soils does not pose any threat of extended herbicide persistence.

Electrochemical determination of bentazone using simple screen-printed carbon electrodes.

Bentazone is one of the most problematic pesticides polluting groundwater resources. It is on the list of pesticides that are mandatory to analyze at water work controls. The current pesticide measuring approach includes manual water sampling and time-consuming chromatographical quantification of the bentazone content at centralized laboratories. Here, we report the use of an electrochemical approach for analytical determination of bentazone that takes 10 s. The electrochemical electrodes were manually screen printed, resulting in the low-cost fabrication of the sensors. The current response was linearly proportional to the bentazone concentration with a R2 ~ 0.999. We demonstrated a sensitivity of 0.0987 µA/µM and a limit of detection of 0.034 µM, which is below the U.S. Health Advisory level. Furthermore, the sensors have proved to be reusable and stable with a drop of only 2% after 15 times reuse. The sensors have been applied to successfully quantify bentazone spiked in real groundwater and lake water. The sensing method presented here is a step towards on-site application of electrochemical detection of pesticides in water sources.

Lethal Bentazone Intoxication - A Report of Two Cases.

This study presents two cases of lethal bentazone poisonings, their clinical presentation, the course of the disease and the autopsy findings. The first is a 50-year-old male who had sprayed corn with a solution of bentazone and was admitted to the hospital with sweating, fever, nausea, vomiting of aqueous and hemorrhagic content, and bloody, watery stools. He was treated according to the symptoms including extracorporeal hemodialysis, but eventually suffered from multiorgan failure (acute respiratory failure, acute liver failure, coagulopathy, acute renal failure, metabolic acidosis, and gastrointestinal bleeding) and died 11.35 h after admittance. The cause of death was probable bentazone intoxication. The second case, also a male, aged 49 who committed suicide by ingesting a bentazone solution. He was transferred to the hospital prostrated and cyanotic and died 14.15 h after admittance despite all efforts by the hospital staff. The cause of death was acute bentazone intoxication.

Methods comparison, transport and distribution of polar herbicides in the Baltic Sea.

Two LC-MS/MS methods including different sample preparation and quantitative processes showed a good agreement for analysis of the herbicides MCPA, mecoprop, isoproturon, bentazon and chloridazon, and the metabolite chloridazon-methyl-desphenyl (CMD) in estuarine waters. Due to different sensitivity of the methods only one could be used to analyze marine samples. The transport of these compounds to the Baltic Sea via ten German estuaries and their distribution between coastal water and sediments was studied. The results showed that all selected compounds can be transported to the Baltic Sea (0.9-747ng/L). Chloridazon, bentazon, isoproturon and CMD were detected (0.9-8.9ng/L) in the coastal waters and chloridazon and isorproturon in the sediments (5-136pg/g d.w.). Levels of contaminants in the sediments could be influenced by the total organic carbon content. Concentrations observed in the Baltic Sea are most likely not high enough to cause acute effects, but long term effect studies are strongly recommended.

Dissipation and Residues of Dichlorprop-P and Bentazone in Wheat-Field Ecosystem.

Dichlorprop-P and bentazone have been widely used in the prevention and control of weeds in wheat field ecosystems. There is a concern that pesticide residues and metabolites remain on or in the wheat. Thus, the study of the determination and monitoring of their residues in wheat has important significance. A rapid, simple and reliable QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was modified, developed and validated for the determination of dichlorprop-P, bentazone and its metabolites (6-hydroxy-bentazone and 8-hydroxy-bentazone) in wheat (wheat plants, wheat straw and grains of wheat) using high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The average recoveries of this method ranged from 72.9% to 108.7%, and the limits of quantification (LOQs) were 2.5-12 µg/kg. The dissipation and final residue of four compounds in three provinces (Shandong, Jiangsu and Heilongjiang) in China were studied. The trial results showed that the half-lives of dichlorprop-P and bentazone were 1.9-2.5 days and 0.5-2.4 days in wheat plants, respectively. The terminal residues in grains of wheat and wheat straw at harvest were all much below the maximum residue limit (MRL) of 0.2 mg/kg for dichlorprop-P and 0.1 mg/kg for bentazone established by the European Union (EU, Regulation No. 396/2005).

Dissipation of bentazone, pyrimethanil and boscalid in biochar and digestate based soil mixtures for biopurification systems.

Biopurification systems, such as biofilters, are biotechnological tools to prevent point sources of pesticide pollution stemming from on-farm operations. For the purification processes pesticide sorption and mineralization and/or dissipation are essential and both largely depend on the type of filling materials and the pesticide in use. In this paper the mineralization and dissipation of three contrasting (14)C-labeled pesticides (bentazone, boscalid, and pyrimethanil) were investigated in laboratory incubation experiments using sandy soil, biochar produced from Pine woodchips, and/or digestate obtained from anaerobic digestion process using maize silage, chicken manure, beef and pig urine as feedstock. The results indicate that the addition of digestate increased pesticide mineralization, whereby the mineralization was not proportional to the digestate loads in the mixture, indicating a saturation effect in the turnover rate of pesticides. This effect was in correlation with the amount of water extractable DOC, obtained from the digestate based mixtures. Mixing biochar into the soil generally reduced total mineralization and led to larger sorption/sequestration of the pesticides, resulting in faster decrease of the extractable fraction. Also the addition of biochar to the soil/digestate mixtures reduced mineralization compared to the digestate alone mixture but mineralization rates were still higher as for the biochar/soil alone. In consequence, the addition of biochar to the soil generally decreased pesticide dissipation times and larger amounts of biochar led to high amounts of non-extractable residues of pesticide in the substrates. Among the mixtures tested, a mixture of digestate (5%) and biochar (5%) gave optimal results with respect to mineralization and simultaneous sorption for all three pesticides.

Re-evaluation of groundwater monitoring data for glyphosate and bentazone by taking detection limits into account.

Current regulatory assessment of pesticide contamination of Danish groundwater is exclusively based on samples with pesticide concentrations above detection limit. Here we demonstrate that a realistic quantification of pesticide contamination requires the inclusion of "non-detect" samples i.e. samples with concentrations below the detection limit, as left-censored observations. The median calculated pesticide concentrations are shown to be reduced 10(4) to 10(5) fold for two representative herbicides (glyphosate and bentazone) relative to the median concentrations based upon observations above detection limits alone.

Simple SPE-HPLC determination of some common drugs and herbicides of environmental concern by pulsed amperometry.

In this work the electrochemical behavior of substances of environmental concern [bentazone, atrazine, carbamazepine, phenytoin and its metabolite 5-(4-hydroxyphenyl)-5-phenylhydantoin, HPPH] on a glassy carbon working electrode (Ag/AgCl reference electrode) was studied with the aim to develop a HPLC method coupled with amperometric detection. Constant potential (DC), pulsed amperometric detection modes were studied. For the pulsed mode, several waveforms were set and investigated. Detection conditions were optimized as a function of eluent pH. In order to reduce the limits of detection and to analyze natural water samples, a SPE protocol was optimized to be coupled to the developed procedure. For this aim, five sorbents of different physico-chemical characteristics were tested optimizing a recovery procedure for each of the cartridge evaluated. At the optimized SPE conditions, recoveries were included in the range (R=90.2-100.5% for all the analytes, with excellent reproducibility (<%, n=3). The method detection limits obtained by pulsed amperometry after the SPE protocol (preconcentration factor 100) were 113 ng L(-1) (0.47 nmol L(-1)), 67 ng L(-1) (0.25 nmol L(-1)), 234 ng L(-1) (1.1 nmol L(-1)), for bentazone, HPPH and carbamazepine, respectively. Robustness of the method was assessed for each analyte at a concentration level corresponding to about three times the limit of detection, through the evaluation of intra-day (n=13) and inter-day tests (4 days, n=52). Finally the method was successfully applied for the analysis of a river sample (Po River, Turin, Italy).

Influence of biochar amendments on the sorption-desorption of aminocyclopyrachlor, bentazone and pyraclostrobin pesticides to an agricultural soil.

The many advantageous properties of biochar have led to the recent interest in the use of this carbonaceous material as a soil amendment. However, there are limited studies dealing with the effect of biochar on the behavior of pesticides applied to crops. The objective of this work was to determine the effect of various biochars on the sorption-desorption of the herbicides aminocyclopyrachlor (6-amino-5-chloro-2-cyclopropyl-4-pyrimidinacarboxylic acid) and bentazone (3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide) and the fungicide pyraclostrobin (methyl 2-[1-(4-chlorophenyl) pyrazol-3-yloxymethil]-N-methoxycarbanilate) to a silt loam soil. Aminocyclopyrachlor and bentazone were almost completely sorbed by the soils amended with the biochars produced from wood pellets. However, lower sorption of the herbicides was observed in the soils amended with the biochar made from macadamia nut shells as compared to the unamended soil, which was attributed to the competition between dissolved organic carbon (DOC) from the biochar and the herbicides for sorption sites. Our results showed that pyraclostrobin is highly sorbed to soil, and the addition of biochars to soil did not further increase its sorption. Thus, addition of biochars to increase the retention of low mobility pesticides in soil appears to not be necessary. On the other hand, biochars with high surface areas and low DOC contents can increase the sorption of highly mobile pesticides in soil.

Evaluation of the partial renewal of in situ phytoplankton microcosms and application to the impact assessment of bentazon and dimethenamid.

Microcosms, each consisting of 2L natural surface seawater maintained in 2.3-L glass bottles, were immersed at a depth of 6m. The renewal of 10% of microcosm volumes was carried out every other day. Phytoplankton-containing seawater was used for renewal (previously filtered through 25-, 50- or 200-µm cut-off). Phytoplankton community pigment analysis (by HPLC) and flow cytometry analysis were performed. After 13 days, data exhibited phytoplankton characteristics in microcosms in the same range as that of the natural surrounding sea water over the same period. Furthermore, in these microcosms, a negative correlation was observed between the filtration cut-off used for renewal water, and the total cell count. Herbicides were tested as commercial mixtures at 1, 10 and 100 µgL(-1) active substance. Both Frontier® (dimethenamid) and Basamais® (bentazon) induced significant modifications of the phytoplankton populations at every concentration tested. Such results suggest a possible disturbance in polluted coastal areas.

Photocatalytic degradation of bentazone in soil washing wastes containing alkylpolyoxyethylene surfactants.

Three alkylpolyoxyethylene surfactants bearing the same hydrophobic chain and a different number of oxyethylene groups were investigated as suitable candidates for the soil washing treatment of contaminated soil samples containing bentazone. Comparable good recoveries of the pesticide were obtained working with these surfactants. The photocatalytic treatment of the collected washing wastes, performed in the presence of suspended TiO(2) particles under irradiation with simulated sunlight, leads to the effective degradation of bentazone residues after a time depending on the nature and concentration of the chosen amphiphile. Brij 35 was found to be the best surfactant candidate, giving the faster abatement of the pesticide in the collected wastes. The overall treatment time depends on the bentazone mineralization kinetics, markedly slow in the presence of surfactants. Useful information about the photocatalytic degradation route was obtained from the HPLC-MS analysis of transient intermediates formed in water.

Measurements and modeling of pesticide persistence in soil at the catchment scale.

Degradation of pesticides in soils is both spatially variable and also one of the most sensitive factors determining losses to surface water and groundwater. To date, no general guidance is available on suitable approaches for dealing with spatial variation in pesticide degradation in catchment or regional scale modeling applications. The purpose of the study was therefore to study the influence of various soil physical, chemical and microbiological characteristics on pesticide persistence in the contrasting cultivated soils found in a small (13 km(2)) agricultural catchment in Sweden and to develop and test a simple model approach that could support catchment scale modeling. Persistence of bentazone, glyphosate and isoproturon was investigated in laboratory incubation experiments. Degradation rate constants were highly variable with coefficients of variation ranging between 42 and 64% for the three herbicides. Multiple linear regression analysis and Mallows Cp statistic were employed to select the best set of independent parameters accounting for the variation in degradation. Soil pH and the proportion of active microorganisms (r) together explained 69% of the variation in the bentazone degradation rate constant; the Freundlich sorption co-efficient (K(f)) and soil laccase activity together explained 88% of the variation in degradation rate of glyphosate, while soil pH was a significant predictor (p<0.05) for isoproturon persistence. However, correlations between many potential predictor variables made clear interpretations of the statistical analysis difficult. Multiplicative models based on two predictors chosen 'a priori', one accounting for microbial activity (e.g. microbial respiration, laccase activity or the surrogate variable soil organic carbon, SOC) and one accounting for the effects of sorption on bioavailability, showed promise to support predictions of degradation for large-scale modeling applications, explaining up to 50% of the variation in herbicide persistence.

Factors responsible for rapid dissipation of acidic herbicides in the coastal lagoons of the Camargue (Rhône River Delta, France).

This study was aimed at investigating which processes cause acidic herbicides (e.g., bentazone, MCPA and dichlorprop) to rapidly disappear in the lagoons of the Rhône delta, which are peculiar brackish and shallow aquatic environments. The use of the model MASAS (Modeling of Anthropogenic Substances in Aquatic Systems) revealed that sorption, sedimentation, volatilization, flushing and abiotic hydrolysis had a minor role in the attenuation of the investigated herbicides. Laboratory scale biodegradation and photodegradation studies were conducted to better assess the significance of these two processes in the natural attenuation of herbicides in brackish (lagoons) waters with respect to fresh waters (canals draining paddy fields). Herbicide biodegradation rates were significantly lower in lagoon water than in canal water. Consequently, photodegradation was the main dissipation route of all investigated herbicides. The contribution of indirect photolysis was relevant for MCPA and dichlorprop while direct photolysis dominated for bentazone removal. There is a need to further investigate the identity of phototransformation products of herbicides in lagoons.

Transport and degradation of pesticides in a biopurification system under variable flux Part II: A macrocosm study.

Transport of bentazone, isoproturon, linuron, metamitron and metalaxyl were studied under three different flows in macrocosms. The aim was to verify the observations from Part I of the accompanying paper, with an increase in column volume and decrease in chemical and hydraulic load. Very limited breakthrough occurred in the macrocosms for all pesticides, except bentazone, at all flows. From batch degradation experiments, it was observed that the lag time of metamitron and linuron decreased drastically in time for all flows, indicating a growth in the pesticide degrading population. This in contrast to isoproturon and metalaxyl, where an increase in lag time could be observed in time for all flows. From the batch degradation experiments, it could be concluded that the influence of flow on the lag time was minimal and that the inoculation of the pesticide-primed soil had a little surplus value on degradation.

Transport and degradation of pesticides in a biopurification system under variable flux, Part I: a microcosm study.

The efficiency of a biopurification system, developed to treat pesticide contaminated water, is to a large extent determined by the chemical and hydraulic load. Insight into the behaviour of pesticides under different fluxes is necessary. The behaviour of metalaxyl, bentazone, linuron, isoproturon and metamitron was studied under three different fluxes with or without the presence of pesticide-primed soil in column experiments. Due to the time-dependent sorption process, retention of the pesticides with intermediate mobility was significantly influenced by the flux. The higher the flux, the slower pesticides will be sorbed, which resulted in a lower retention. Degradation of the intermediate mobile pesticides was also submissive to variations in flux. An increase in flux, led to a decrease in retention, which in turn decreased the opportunity time for biodegradation. Finally, the presence of pesticide-primed soil was only beneficial for the degradation of metalaxyl.

[Determination of biphenyl ether herbicides in water using HPLC with cloud-point extraction].

OBJECTIVE: To determine residues of multiple biphenyl ether herbicides simultaneously in water using high performance liquid chromatography (HPLC) with cloud-point extraction. METHODS: The residues of eight biphenyl ether herbicides (including bentazone, fomesafen, acifluorfen, aclonifen, bifenox, fluoroglycofenethy, nitrofen, oxyfluorfen) in water samples were extracted with cloud-point extraction of Triton X-114. The analytes were separated and determined using reverse phase HPLC with ultraviolet detector at 300 nm. Optimized conditions for the pretreatment of water samples and the parameters of chromatographic separation applied. RESULTS: There was a good linear correlation between the concentration and the peak area of the analytes in the range of 0.05-2.00 mg/L (r = 0.9991-0.9998). Except bentazone, the spiked recoveries of the biphenyl ether herbicides in the water samples ranged from 80.1% to 100.9%, with relative standard deviations ranging from 2.70% to 6.40%. The detection limit of the method ranged from 0.10 microg/L to 0.50 microg/L. CONCLUSION: The proposed method is simple, rapid and sensitive, and can meet the requirements of determination of multiple biphenyl ether herbicides simultaneously in natural waters.

GIS based ArcPRZM-3 model for bentazon leaching towards groundwater.

Groundwater contamination due to pesticide applications on agricultural lands is of great environmental concern. The mathematical models help to understand the mechanism of pesticide leaching in soils towards groundwater. We developed a user-friendly model called ArcPRZM-3 by integrating widely used Pesticide Root Zone Model version 3 (PRZM-3) using Visual Basic and Geographic Information System (GIS) based Avenue programming. ArcPRZM-3 could be used to simulate pesticide leaching towards groundwater with user-friendly input interfaces coupled with databases of crops, soils and pesticides. The outputs from ArcPRZM-3 could be visualized in user-friendly formats of tables, charts and maps. In this study we evaluated ArcPRZM-3 model by simulating bentazon leaching in soil towards groundwater. ArcPRZM-3 was applied to 37 sites in Woodruff County, Arkansas, USA to observe the daily average dissolved bentazon concentration for soybean, sorghum and rice at a depth of 1.8 m for a period of two years. Nineteen ranks of bentazon leaching potential were obtained using ArcPRZM-3 for all sites having different soil and crop combinations. ArcPRZM-3 simulation results for bentazon were compatible with the field monitored data in term of relative ranking and trend, although some uncertainties exist. This study indicated that macropore flow mechanism would be important in analyzing the effect of irrigation on groundwater contamination due to pesticides. Overall, ArcPRZM-3 could be used to simulate pesticide leaching towards groundwater more efficiently and effectively as compared to PRZM-3.

Influence of surfactants on the leaching of bentazone in a sandy loam soil.

BACKGROUND: Surfactants are very often used for more efficient pesticide spraying, but knowledge about their influence on the leaching potential for pesticides is very limited. In the present study, the leaching of the herbicide bentazone [3-isopropyl-1H-2, 1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] was measured in columns with sandy loam soil with or without the addition of a non-ionic surfactant, octylphenol ethylene oxide condensate (Triton X-100, Triton), and an anionic surfactant, sodium dodecylbenzenesulfonate (SDBS), and in the presence of both surfactants (SDBS + Triton). RESULTS: The mobility of bentazone (B) increased in the following order: B + Triton (slowest) < B + SDBS + Triton < B < B + SDBS (fastest). When Triton X-100 was applied to the soil together with bentazone, the leaching of bentazone in the soil decreased significantly compared with leaching of bentazone without the addition of surfactant. SDBS and Triton X-100 neutralised their influence on the leaching speed of bentazone in the soil columns when both surfactants were applied with bentazone. CONCLUSION: From the study it can be concluded that, depending on their properties, surfactants can enhance or reduce the mobility of bentazone. By choosing a non-ionic surfactant, bentazone mobility can be reduced, giving time for degradation and thereby reducing the risk of groundwater pollution.