Electrochemical preparation of a poly(aniline-co-m-aminobenzoic acid)–ionic liquid composite coating for the head-space solid phase microextraction and analysis of aryl halides†
In this work, a novel poly(aniline-co-m-aminobenzoic acid)–ionic liquid composite coating is presented for the head-space solid phase microextraction (HS-SPME) of aryl halides (i.e. chlorobenzene, bromobenzene, 1,4-dichlorobenzene, 4-bromotoluene, and 1,2,4-trichlorobenzene). This coating was prepared on a platinum wire by electrochemical deposition in an aqueous solution containing 0.1 mol L−1 aniline, 0.1 mol L−1m-aminobenzoic acid, 0.02 mol L−1 1-butyl-3-methylimidazolium tetrafluoroborate and 1.0 mol L−1 HNO3. It showed high mechanical stability, thermal stability (up to 320 °C) and durability (repetitively used for more than 120 times). When it was applied to the HS-SPME and gas chromatographic detection of aryl halides, it presented high repeatability and sensitivity. Under the optimized conditions (i.e. extraction temperature: 30 °C; extraction time: 30 min; stirring rate: 600 rpm; NaCl concentration: 0.35 g mL−1), the linear detection ranges were 0.2–100 μg L−1 with correlation coefficients above 0.9922; the detection limits were 0.01–0.05 μg L−1 (S/N = 3). The relative standard deviations (RSDs) of chromatographic peak areas were smaller than 5.3% for five successive measurements with a single fiber, and the fiber to fiber RSD was 2.4–9.5% (n = 3) for different aryl halides (50 μg L−1). This method was successfully applied to the determination of real samples (i.e. moth balls) and the recoveries for the standard added were 85.7 % to 121%.