title: On-line monitoring of the photocatalytic degradation of 2,4-D and dicamba using a solid-phase extraction-multisyringe flow injection system.
abstract: A fully automated on-line system for monitoring the photocatalytic degradation of herbicides was developed using multisyringe flow injection analysis (MSFIA) coupled to a solid phase extraction (SPE) unit with UV detection. The calibration curves were linear in the concentration range of 100-1000 μg L(-1) for 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 500-3000 μg L(-1) for 2,4-dichlorophenoxyacetic acid (2,4-D), while the detection limits were 30 and 135 μg L(-1) for dicamba and 2,4-D, respectively. The monitoring of the photocatalytic degradation (TiO2 anatase/UV 254 nm) of these two herbicides was performed by MSFIA-SPE system using a small sample volume (2 mL) in a fully automated approach. The degradation was assessed in ultrapure and drinking water with initial concentrations of 1000 and 2000 μg L(-1) for dicamba and 2,4-D, respectively. Degradation percentages of approximately 85% were obtained for both herbicides in ultrapure water after 45 min of photocatalytic treatment. A similar degradation efficiency in drinking water was observed for 2,4-D, whereas dicamba exhibited a lower degradation percentage (75%), which could be attributed to the presence of inorganic species in this kind of water.
authors.affiliation: Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Químicas, Cd. Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66451, Mexico.
authors.forename: Carmín
authors.initials: C
authors.lastname: Chávez-Moreno
authors.forename: Laura
authors.initials: L
authors.lastname: Ferrer
authors.forename: Laura
authors.initials: L
authors.lastname: Hinojosa-Reyes
authors.forename: Aracely
authors.initials: A
authors.lastname: Hernández-Ramírez
authors.forename: Víctor
authors.initials: V
authors.lastname: Cerdà
authors.forename: Jorge
authors.initials: J
authors.lastname: Guzmán-Mar
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis* / Q000737:chemistry; D003996:Dicamba / Q000032:analysis* / Q000737:chemistry; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry; D009862:Online Systems / Q000295:instrumentation; D010782:Photolysis; D052616:Solid Phase Extraction / Q000295:instrumentation / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; D003996:Dicamba
keywords: 2,4-D; Dicamba; MSFIA system; On-line monitoring; Photocatalytic degradation; TiO(2)