Monitoring of the pesticide diazinon in soil, stem and surface water of rice fields.
Diazinon is an organophosphorus insecticide (OPP) that is used as a pesticide for Chilo suppressalis (WLK) (Lep., Pyralidae) in rice fields. The extraction of diazinon from soil and the stems of rice plants has been carried out by microwave-assisted extraction (MAE) and the results compared with ultrasonic extraction (USE). The best parameters for MAE are hexane-acetone (8:2 v/v) as a solvent, a 2.5 min extraction time, and 20 ml of the solvent volume. Also, surface-water samples of the rice fields were extracted by solid phase extraction (SPE) using a C18 disc. The optimum conditions of SPE were a sample volume of 750 ml, a pH of 7 and high ionic strength of water. The extracted samples were analyzed by gas chromatography-mass spectrometry (GC-MS). The relative standard deviation (RSD) and regression coefficients related to the linearity were <3.5% (n = 5) and 0.99, respectively. The limit of detection (LOD) is 0.1 ng ml(-1) with selected ion monitoring (SIM) at 137 m/z. The average recoveries of diazinon in soil and stem samples by MAE and surface-water by SPE were 98% (+/-3), 94% (+/-5) and 87% (+/-3), respectively. In June, the concentration of diazinon in soil and stem samples of the rice plants in Guilan province is high (55 ng ml(-1)) and in September is low (2 ng ml(-1)). In surface-water samples, the results are converse. In November, diazinon can not be detected in soil, stem or surface-water samples. Diazinon is degraded to diethylthiophosphoric acid. Also, three microorganism genera (Pseudomonas sp, Flavobacterium sp and Agrobacterium sp) have been found to degrade diazinon in soil and surface water.
Chemistry Research Center, Shahid Beheshti University, Evin, Tehran, Iran. aghassempour@scientist.com
Alireza
A
Ghassempour
Ali
A
Mohammadkhah
Fazel
F
Najafi
Mohammad
M
Rajabzadeh
D001673:Biodegradation, Environmental; D003976:Diazinon / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D005618:Fresh Water / Q000737:chemistry* / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D008872:Microwaves; D012275:Oryza / Q000737:chemistry*; D009994:Osmolar Concentration; D010573:Pesticide Residues / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D018547:Plant Stems / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000302:isolation & purification / Q000378:metabolism; D012997:Solvents; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000302:isolation & purification / Q000378:metabolism
D007306:Insecticides; D010573:Pesticide Residues; D012989:Soil Pollutants; D012997:Solvents; D014874:Water Pollutants, Chemical; D003976:Diazinon