title: Evaluation of zirconocene-based silica phases in organochloride pesticides preconcentration.
abstract: Silica was chemically modified with zirconocenes, namely Cp(2)ZrCl(2), (MeCp)(2)ZrCl(2), (iBuCp)(2)ZrCl(2) and (nBuCp)(2)ZrCl(2) by grafting. Hybrid silica bearing surface indene groups was synthesized by the sol-gel method, followed by metallation with ZrCl(4)2THF. According to RBS measurements, metal content was 0.2-0.3 wt% Zr/SiO(2) for the grafted systems and 4.5 wt% Zr/SiO(2) for the phase prepared by the sol-gel method. The solid phases were evaluated in the adsorption/preconcentration of organochloride (hexachlorobenzene, lindane, heptachlor, heptachlor epoxide, dieldrin and endrin) pesticides from aqueous solution. For comparative reasons, commercial LC-18 phase was also evaluated. Analyte concentration was monitored by GC-ECD. For the grafted phases, the coordination sphere around the metal center seems not to influence the adsorption/desorption properties of these phases vis-à-vis the studied analytes. Recoveries results for both analytes were comparable to those observed in the case of LC-18 in the case of the phases prepared by the sol-gel method. Experiments using ZrO(2) and ZrO(2)/SiO(2) phases led to lower recovery results.
authors.affiliation: Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 91509-900 Porto Alegre, RS, Brazil.
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Geller
authors.forename: Fernanda C
authors.initials: FC
authors.lastname: Stedile
authors.forename: Maria do Carmo R
authors.initials: Mdo C
authors.lastname: Peralba
authors.forename: Tânia M
authors.initials: TM
authors.lastname: Pizzolato
authors.forename: João Henrique Z
authors.initials: JH
authors.lastname: Dos Santos