Abstract
A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 µg L-1, respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1, the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 µg L-1.
Highlights
Organophosphates (OPs) are used as pesticides in different cultures due to its efficiency in pests control.[1]
The term E is defined as the percentage of the total amount, by weight, of the analyte extracted to the organic phase; mi (0.025 μg) corresponds to the initial amount of analyte in the aqueous phase and morg corresponds to the amount of extracted analyte
Where Corg is the analyte concentration in the organic phase, Ci is the initial concentration of the analyte in the sample, Vorg is the volume of organic phase recovered after extraction and Vaq is the volume of the sample solution
Summary
Organophosphates (OPs) are used as pesticides in different cultures due to its efficiency in pests control.[1] Parathion-methyl (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) is an insecticide and acaricide from OPs class. Because it is classified as extremely dangerous, it has been banned or had its restricted use in many developed countries like Japan, USA and Australia. In spite, it is still used in cultures of rice, garlic, wheat, beans in many other developing countries including Brazil.[2] The yearly largescale use of parathion-methyl, as well as low decomposition rates in the environment cause the accumulation of these compounds in soils, from which they are subsequently washed out to enter groundwater and rivers.[3].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
