title: Square-wave voltametric method for determination of molinate concentration in a biological process using a hanging mercury drop electrode.
abstract: A square-wave voltammetric (SWV) method using a hanging mercury drop electrode (HMDE) has been developed for determination of the herbicide molinate in a biodegradation process. The method is based on controlled adsorptive accumulation of molinate for 10 s at a potential of -0.8 V versus AgCl/Ag. An anodic peak, due to oxidation of the adsorbed pesticide, was observed in the cyclic voltammogram at ca. -0.320 V versus AgCl/Ag; a very small cathodic peak was also detected. The SWV calibration plot was established to be linear in the range 5.0 x 10(-6) to 9.0 x 10(-6) mol L(-1); this corresponded to a detection limit of 3.5 x 10(-8) mol L(-1). This electroanalytical method was used to monitor the decrease of molinate concentration in river waters along a biodegradation process using a bacterial mixed culture. The results achieved with this voltammetric method were compared with those obtained by use of a chromatographic method (HPLC-UV) and no significant statistical differences were observed.
authors.affiliation: REQUIMTE/Instituto Superior de Engenharia do Porto, Rua Dr. Bernardino de Almeida 431, 4200-072 Porto, Portugal.
authors.forename: M Fátima
authors.initials: MF
authors.lastname: Barroso
authors.forename: O C
authors.initials: OC
authors.lastname: Nunes
authors.forename: M Carmo
authors.initials: MC
authors.lastname: Vaz
authors.forename: C
authors.initials: C
authors.lastname: Delerue-Matos
mesh_terms: D001381:Azepines / Q000032:analysis*; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D008628:Mercury; D013859:Thiocarbamates / Q000032:analysis*
chemical_list: D001381:Azepines; D013859:Thiocarbamates; C009821:molinate; D008628:Mercury