Evaluation of zirconocene-based silica phases in organochloride pesticides preconcentration

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.