Solid-phase extraction combined with headspace single-drop microextraction of chlorophenols as their methyl ethers and analysis by high-performance liquid chromatography-diode array detection

Solid-phase extraction (SPE) of phenol and chlorophenols, their derivatization to methyl ethers, headspace single-drop microextraction (HS-SDME) of methyl ethers using 1-butanol as extraction solvent, and direct transfer of the drop into the injector for high performance liquid chromatography with diode array detection (HPLC-DAD) have been reported. A flanged-end polytetrafluoroethylene sleeve, 3 mm x 0.5 mm, placed at the tip of the syringe needle, allowed the use of 101,1 solvent drop for extraction. The procedure has been optimized for variables involved in SPE and HS-SDME. A rectilinear relationship was obtained between the amount of chlorophenols and peak area ratio of their methyl ethers/internal standard (4-methoxyacetophenone) in the range 0.01-10 mg L-1, correlation coefficient in the range 0.9956-0.9996, and limit of detection in the range 1.5-3.9 mu g L-1 when HS-SDME alone was used for sample preparation. When using coupled SPE and HS-SDME, the linear range obtained was 0.1-500 mu g L-1, correlation coefficient in the range 0.9974-0.9998, and the limit of detection in the range 0.04-0.08 mu g L-1. Spiked real samples have been analyzed with adequate accuracy, and application of the method has been demonstrated for the analysis of chlorophenols formed upon bamboo pulp bleaching. (C) 2010 Elsevier B.V. All rights reserved.