Photochemical behaviour of carbendazim in aqueous solution.
To elucidate the photochemical behaviour of carbendazim (or MBC) in superficial waters, photolysis studies have been carried out in aqueous solutions at several pH using a UV light source (high pressure mercury arc lamp) or a solar light simulator (xenon arc lamp). The kinetics of photodecomposition of carbendazim was determined using HPLC-DAD and the identification of photoproducts was carried out with HPLC-MS (ESI negative and positive mode). According to the experimental results carbendazim is a rather stable molecule in the dark or in environmental conditions. The pH influence of the environmental medium on the photodegradation rate has been confirmed. The photochemical process can be considerably accelerated in alkaline solutions using HPK-quartz irradiation (quantum efficiency at pH 9 phi = 3.1 x 10(-3) degraded molecule per absorbed photon) while the photodegradation is not as efficient under a simulated sun irradiation (quantum efficiency in the suntest phi = 10(-4) at pH 7). Three photoproducts have been tentatively identified in pure water: 2-aminobenzimidazole, benzimidazole isocyanate and monocarbomethoxy-guanidine (issued from the cleavage of the benzimidazole ring). The last one seems very stable and could be accumulated in the environment.
Boudina
A
A
Laboratoire d'Application de la Chimie à L'environnement (LA.C.E.), UMR CNRS 5634, Université Lyon I. 43, Boulevard du 11 Noviembre 1918, 69622 Villeurbanne Cedex, France.
Emmelin
C
C
Baaliouamer
A
A
Grenier-Loustalot
M F
MF
Chovelon
J M
JM
D001562:Benzimidazoles / Q000737:chemistry* / Q000528:radiation effects; D002219:Carbamates; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D010782:Photolysis; D012996:Solutions; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical
D001562:Benzimidazoles; D002219:Carbamates; D012996:Solutions; D014874:Water Pollutants, Chemical; C027391:2-aminobenzimidazole; C006698:carbendazim