The presence of pesticide residues in locally produced fruits and vegetables in Egypt raises health concerns among consumers. The aims of this study were to determine the contamination level of pesticide residues in some consumed local horticultural products such as oranges, potatoes, tomatoes and grapes in the following Egyptian governorates: Dakahlia,
This work aimed to study the isotherm and kinetics of adsorption of a mixture of 10 pesticides (viz., atrazine, chlorfenvinphos, chlorpyrifos, cyprodinil, diazinon, dimethoate, diuron, ethion, malathion, and profenofos) on corn cob biochar (CCB) in an aqueous solution. CCB is a low-cost adsorbent produced from pyrolysis at 500°C for 3 h in an oxygenlimited condition. It was characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine the residual pesticide concentration. Adsorption equilibrium and kinetics were investigated by using batch adsorption experiments. The optimized pH, contact time, adsorbent dose, and initial pesticides concentration for the maximum adsorption rates were found to be 3, 60 min, 10 g/L, and 500 μg/L, respectively. The sorption of all pesticides by CCB was found to enhance by decreasing pH; since the removal percentage of atrazine increased from 57 to 74 % by decreasing the pH from 9 to 3. The Langmuir model represented the adsorption process better than the Freundlich model with R 2 values ranging from 0.957 to 0.999. Adsorption kinetic data were fitted well with the pseudo-first order kinetic model. Accordingly, CCB can be used as an effective low-cost agricultural waste that could be applied for removing pesticide residues from water.
A multi-residue method for the quantification of 9 organochlorine pesticides, one synthetic pyrithroid and 7 members of PCBs compounds residues in fish is described. The method involves the application of a modified pesticide manual procedure followed by GC-ECD (Gas Chromatography coupled with Electron Capture Detector) analysis. The method is validated according to the European Union SANCO/12495/2011 guidelines and Pesticide Manual of Analytical methods. The validation levels were 0.01; 0.04; and 0.2 mg /kg for organochlorines except fenopropathrin (a synthetic pyrithroid insecticide) which has been validated at the concentration of 0.02, 0.08 and 0.4 mg /kg and for PCBs at 0.005, 0.02 and 0.1 mg/kg. Acceptable values were obtained for the following parameters: limit of detection LOD (ranged between 0.003-0.009 mg/kg for organochlorine pesticides and 0.002 mg/kg for PCB's) and limit of quantification (LOQ) (0.005 mg/kg for PCB's and in the range of 0.01-0.02 mg/kg for organochlorine compounds). The recovery percentages ranged between 70 and 120%, and the measurement uncertainty tests was ±40.0%. The method showed to be linear from the LOQ up to the maximum level; 0.1 mg/kg for PCB's and in the range of 0.2-0.4 mg/kg for organochlorine compounds. These results demonstrate the applicability of this method in the routine practice for detecting the residues of such compounds in fatty food.
The degradation rates and residue levels of malathion as an insecticide and its metabolite malaoxon were studied on field grown four varieties of mango trees (Alfouns, Zebdia, Fajeri Klan, and Langra). The samples were collected after one hour, 1, 3, 5, and 7 days post insecticide application. The data showed that the recovery rates of QUCHER method were satisfied for both malathion and malaoxon. The obtained rates of recovery were 97 and 99% for malathion and malaoxon, respectively. The obtained residues of both compounds under investigation (malathion and malaoxon) decreased gradually with time, whereas, and there were no residues found 5 days later for malathion. Also, malaoxon showed the same pattern of degradation thus it disappeared after 3 days from treatment. The half-life time values of malathion (LT 50 ) ranged from 0.96 to 2.8 days in these four mango varieties while they were ranged between 0.43 to 0.9 days for malaoxon. The pre-harvest interval (PHI) for each compound was determined according to their maximum residue limits which were 3 and 2 days for malathion and malaoxon, respectively on all four varieties of mango fruits.
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