Multi-walled carbon nanotubes as solid-phase extraction adsorbents for determination of atrazine and its principal metabolites in water and soil samples by gas chromatography-mass spectrometry

A novel, simple, cost-effective, and sensitive method was developed for the determination of atrazine and its principal metabolites namely deisopropyl-atrazine (DIA) and deethyl-atrazine (DEA) in water and soil samples using multi-walled carbon nanotubes as solid-phase extraction (SPE) adsorbents coupled with gas chromatography-mass spectrometry (GC-MS). Several condition parameters, such as sample loading flow-rate, eluent and elution volume, extractant and ratio of extraction solvent to sample, were optimized to achieve good sensitivity and precision for the extraction and elution of analytes. A methanol/water solution (50%, v/v) was used to extract atrazine, DIA and DEA from soil. After the extracts went through SPE cartridges (packed with multi-walled carbon nanotubes) at a flow-rate of 4 ml, min(-1), the analytes were eluted by 4 mL ethyl acetate at the rate of 1 mL min(-1) under a vacuum pump. The limit of detection (S/N=3) of the proposed method was 0.02 mu g kg(-1) for atrazine in water and 0.3 mu g kg(-1) in soil; 0.04 mu g kg(-1) for DIA in water and 1.0 mu g kg(-1) in soil; 0.05 mu g kg(-1) for IDEA in water and 0.8 mu g kg(-1) in soil. Mean recoveries were in the range of 72.27-109.68%, and the reproducibility was accepted (RSD <13%) under the optimum conditions. This developed method was applied to determine the analytes in real environmental samples, and the concentrations of atrazine were 0.77-10.83 mu g kg(-1), while DEA and DIA were not detected. (C) 2008 Elsevier B.V. All rights reserved.