The simultaneous degradation of prochloraz and tebuconazole in water with identification and degradation of their main degradation products using liquid chromatography-tandem mass spectrometry (original) (raw)
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Prochloraz and tebuconazole are well-known fungicides for broad-spectrum applications, including; medical, industrial, and agricultural. These fungicides are frequently used simultaneously for the protection of various agricultural products. The presence of these fungicides in water doesn't only affect the health of direct consumers but also limits their reuse. In this study, complete degradation of these fungicides and their degradation products were accomplished using thermal-activated persulfate. It takes only 30 min to degrade 97% and 98% of PCZ and TBZ, respectively, in their single presence in water using 1.4 mM persulfate and a temperature of 50 ºC. However, in their simultaneous presence in water, a treatment for a complete one hour is required to degrade 99% and 94% for PCZ and TBZ, respectively, at the same degradation conditions. The persulfate degradation of prochloraz was conducted by the cleavage of the imidazole ring and the subsequent formation of a trichlorophen...
Interdisciplinary Toxicology, 2008
A two season (2005)(2006)(2007)) study on persistence of propineb (Propineb 70% WP) was undertaken in Tomato (at two locations) following the application at two doses 2.0 and 4.0 kg a.i ha -1 . More than 92% of the initial residues dissipated within 10 days after application irrespective of doses, seasons and locations. The residue was detectable up to 15 days after application. Assuming first order kinetics the half-life values varied from 2.11 to 2.64 days. The safe waiting periods of 7 days are recommended for Tomato.
International Journal of Environmental Analytical Chemistry, 2020
Fungal diseases like downy and powdery mildews are a risk of high importance for strawberry cultivation in Egypt. In the current work, the dissipation behaviour of tebuconazole, a triazole fungicide widely used worldwide, was studied and the safety to the consumers from the terminal residues in the fruits was estimated. Supervised trials on open field strawberries were concluded using the authorised and more critical agricultural practices. Residues were measured at several PHIs using an LC-MS/MS methodology with an extraction procedure based on the QuEChERS protocol. The method was successfully validated with an LOQ of 0.001 mg kg −1. In all PHIs investigated a consumer risk was not identified. A decline of tebuconazole residues in fruits fit a first-order decay process with a degradation of 81% after 14 days and a calculated t 1/2 of 6.3 days ARTICLE HISTORY
Journal of Chromatography A, 1995
A method was developed that allows the determination of benomyl, carbendazim (MBC), thiophanate methyl (TFM) as carbendazim and thiabendazole (TBZ) by HPLC with UV detection. After extraction and cyclization of TFM into MBC, the conversion of benomyl into MBC is carried out by absorbing the raw extract on a ready-to-use, disposable column of a macroporous Kieselghur-type material and percolating 0.1 M HCI through it. Benzimidazolic residues are partitioned into the acid solution whereas most of the co-extractives are retained on the column. The final clean-up is performed on a strong cation-exchange (SCX) cartridge. The determination of MBC and TBZ is carried out by HPLC-UV detection on a polymeric reversed-phase column eluted with a water-acetonitrile (70:30). Recoveries of MBC and TBZ from pear, apple, orange, grape, kiwi, tomato and lettuce, spiked at levels of 0.22 and 0.88 mg/kg, were satisfactory (>70%). The main features of the method include high selectivity towards MBC and TBZ, reduced consumption of reagents and solvents, reduced handling operations, lack of emulsions and the use of disposable items.
Azole Fungicides: Occurrence and Fate in Wastewater and Surface Waters
Environmental Science & Technology, 2008
The mode of action of azole compounds implies a potential to affect endocrine systems of different organisms and is reason for environmental concern. The occurrence and fate of nine agricultural azole fungicides, some of them also used as biocides, and four azole pharmaceuticals were studied in wastewater treatment plants (WWTPs) and lakes in Switzerland. Two pharmaceuticals (fluconazole, clotrimazole, 10-110 ng L-1) and two biocides (propiconazole, tebuconazole, 1-30 ng L-1) were consistently observed in WWTP influents. Loads determined in untreated and treated wastewater indicated that fluconazole, propiconazole, and tebuconazole were largely unaffected by wastewater treatment, but clotrimazole was effectively eliminated (>80%). Incubation studies with activated sludge showed no degradation for fluconazole and clotrimazole within 24 h, but strong sorption of clotrimazole to activated sludge. Slow degradation and some sorption were observed for tebuconazole and propiconazole (degradation half-lives, 2-3 d). In lakes, fluconazole, propiconazole, and tebuconazole were detected at low nanogram-per-liter levels. Concentrations of the pharmaceutical fluconazole correlated with the expected contamination by domestic wastewater, but not those of the biocides. Per capita loads of propiconazole and tebuconazole in lakes suggested additional inputs; for example, from agricultural use or urban runoff rainwater.
Studies of the Analysis of Pesticide Degradation in Environmental Samples
Current Analytical Chemistry, 2010
This article presents an overview of the different analytical methods available for performing pesticide degradation studies in water and environmental samples by different processes. How long the pesticide remains in the environment depends on how strongly it is bounded by other components and how readily it is degraded. It is also depends on the environmental conditions at the time of application, pH, temperature, soil and water content. The degree of mineralization achieved under advanced oxidation processes (AOP), photo-Fenton reactions [FR], and ozonation processes, and the identity of by-products of a large number of compounds belonging to the major pesticide families pirethroides, organochlorides and organophosphorus compounds are presented. Critical comments are aimed at emphasizing the lack of suitable analytical methods adequate to determine the kinetics of both the formation and disappearance of by-products and to identify their chemical structures. More specifically, the crucial role of gas chromatography and liquid chromatography in combination with mass spectrometry is described. In the following manuscript, an overview of the pesticide degradation phenomena is given, and an attempt is made to predict how factors and conditions influence the phenomena. SPME and GC/MS are sufficiently accurate methods to support the identification of pesticides in different degradation processes.
Degradative fate of 3-chlorocarbazole and 3,6-dichlorocarbazole in soil
Environmental Science and Pollution Research, 2011
Background, aim, and scope 3-Chlorocarbazole and 3,6dichlorocarbazole were isolated from Bavarian soils. The stereospecific formation of the isomers of these chlorinated carbazols can be explained by quantum mechanical calculations using the DFT method. It was shown that chlorination of carbazole and 3-chlorocarbazole respectively is preferred via the sigma-complexes 3-chlorocarbazole and 3,6-dichlorocarbazole as the most stable products. The dioxin-like toxicological potential of 3,6-dichlorocarbazole, determined by the Micro-EROD Test, is in the range of some picogram TCDD equivalents per milligram carbazole. The degradative fate of 3-chlorocarbazole and 3,6-dichlorocarbazole was analysed within a long-term study (57 days) in soil.
Dissipation kinetics and leaching of cyazofamid fungicide in texturally different agricultural soils
International Journal of Environmental Science and Technology
Dissipation and leaching studies of cyazofamid in two texturally different soils of Tarai region of India at two fortification levels (100 and 200 g a.i. ha-1) were carried out for monitoring residual toxicity and groundwater contamination. Soil was extracted with acetone : methanol (5:1 v/v) followed by cleanup with florisil SPE. Separation was achieved by RP-HPLC on a Discovery Ò C-18 column using mobile phase acetonitrile: water (60:40 v/v) and detection at 279 nm. Degradation pattern indicated correspondence to monophasic first-order kinetics in soils with half-life values ranging from 4.3 to 4.95 days. The degradation rate was slight different in both types of soils. Persistence was higher in sandy loam compared to silty clay loam soil. Linearity, R 2 of calibration curve, instrument limit of detection/quantitation (LOD/LOQ) was evaluated. Good linearity (R 2 = 0.99) of the calibration curves for quantification was obtained over the dynamic range of 0.1-10.0 lg mL-1 , and percent relative standard deviation was 1.72 %. Leaching experiment showed that cyazofamid could not leached beyond 15 cm of soil depth. Maximum concentration was at 5-10 and 10-15 cm soil depth. Average recoveries from soils fortified at 0.5-5.0 lg g-1 ranged from 78 to 86 %. Instrument LOD values were 0.01 lg mL-1 , and method LOQ values were 0.05 lg g-1. A fast, easy and efficient method with acceptable performance was achieved. Results showed that cyazofamid has a short life in soils and low potential to leach down under heavy rainfall conditions. Results confirm that cyazofamid would not build up in the environment and have less possibility of groundwater contamination.