Determination photostability of selected agrochemicals in water and soil

Identification of photocatalytic degradation products of diazinon in TiO2aqueous suspensions using GC/MS/MS and LC/MS with quadrupole time-of-flight mass spectrometry

“…The abiotic environmental fate of diazinon has been well studied previously; it is stable at neutral waters, while it is rapidly hydrolyzed at acidic pH [8]. Hydrolysis products have been identified as 2-isopropyl-6-methyl-pyrimidin-4-ol (IMP) and diethyl thiophosphate [9]. Diazinon is slowly photodegraded in distilled water under sunlight, while in natural waters the process is significantly faster [10,11].…”

“…2-Isopropyl-6-methylpyrimidin-4-ol has been identified as the main photoproduct [8]. Photolysis studies of diazinon in soil aqueous suspensions under UV light have shown that the main transformation products are its oxygen analogue, diethyl 2-isopropyl-6-methylpyrimidin-4-yl phosphate (diazoxon), its isomer O,O-diethyl S-(2-isopropyl-6-methylpyrimidin-4-yl) thiophosphate) (isodiazinon), and O,Odiethyl O-[2-(1-hydroxy-1-methylethyl)-6-methylpyrimidin-4-yl] thiophosphate (hydroxydiazinon) [9]. Because diazinon transformation products are more polar than the parent compound, they may be consequently more water soluble, more mobile, and have a greater potential to leach from soil.…”

“…Compounds (1) and (2), which were detected at retention times of 19.0 and 25.8 min respectively, were identified by comparison with authentic standards as 2-isopropyl-6-methylpyrimidin-4-ol (IMP) and diaz- IMP is the hydrolysis product of diazinon formed through the cleavage of P¢O(pyrimidine group) bond, that has been found in water, soil, plants, and animals [9,29]. Diazoxon (Mr 288), the oxygen analogue of diazinon in which S has been replaced by an O atom, has been reported to be a diazinon photolysis product in water/soil suspensions [9] and is a diazinon metabolite formed in vitro and in vivo in studies with animals [30].…”

“…Diazoxon (Mr 288), the oxygen analogue of diazinon in which S has been replaced by an O atom, has been reported to be a diazinon photolysis product in water/soil suspensions [9] and is a diazinon metabolite formed in vitro and in vivo in studies with animals [30]. The base peak at m/z 137 in the positive ion EI mass spectrum (Figure 4a) of diazoxon is similar to that of diazinon and IMP, but the fragment ion corresponding to the ethyl ether of the pyrimidine group (m/z 179) was not observed.…”

Photodegradation kinetics of fenitrothion in various aqueous media and its effect on steroid hormones biosynthesis

“…Pesticides undergo transformation by indirect photolysis via dissolved matters in various bodies of water. This process is responsible for the disappearance and the enhanced photooxidation rates of organic compounds through the production of photoreactants such as hydroxyl radicals (Mansour et al, 1999). Therefore, photodegradation studies of pesticides allow for the modeling of pesticide Nishikawa, 1995;Itagaki et al, 2000;Kondoh et al, 2001;Tanabe et al, 2001;Sudo et al, 2002).…”