title: Determination of atrazine using square wave voltammetry with the Hanging Mercury Drop Electrode (HMDE).
abstract: This paper presents the optimization of instrumental and solution parameters for determination of atrazine in river waters and formulation by square wave voltammetry (SWV) using a hanging mercury drop electrode. The best sensitivity (35.2+/-0.4muAmlmug(-1)) was achieved using a frequency of 400Hz and a medium composed of 40mmoll(-1) Britton-Robinson (BR) buffer at pH 1.9. The detection limit was 2mugl(-1) with a linear dynamic range between 10 and 250mugl(-1). Application of the method to real samples of river waters fortified with 10mugl(-1) of atrazine resulted recoveries between 92 and 116%. Additionally, good agreement was observed between results obtained by the proposed method and by HPLC for river water samples spiked with 25mugl(-1) of atrazine. The determination was not affected by the presence of humic acid at concentration of 5mgl(-1), indicating that interactions of the herbicide with this class of compounds are fully labile. The stability of the voltammetric signal for samples spiked with 250mugl(-1) atrazine was evaluated over a period of 14 days in four samples. For two samples, no systematic variation was observed, while for the other two, a decrease of peak current between 3 and 15% occurred, suggesting that the stability is dependent on the sample nature. HPLC analyses suggest formation of deethylatrazine during the second week of storage in the samples for which the SWV peak current had the more intense decrease.
authors.affiliation: Instituto de Quimica, Universidade de São Paulo, C.P. 26077, 05513-970, São Paulo, SP, Brazil.
authors.forename: Luciana B O
authors.initials: LB
authors.lastname: Dos Santos
authors.forename: Gilberto
authors.initials: G
authors.lastname: Abate
authors.forename: Jorge C
authors.initials: JC
authors.lastname: Masini