Oxide Graphene Doped Electrochemical Copolymer Coating of 2,2-Bithiophene and 5-Methoxyindole for Solid-phase Microextraction of Antidepressants

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Poly(2,2-bithiophene-co-5-methoxyindole)-oxide graphene composite coating was prepared by voltammetry for headspace solid-phase microextraction and gas chromatography determination of antidepressants (i.e., citalopram, fluoxetine and nortriptyline). The coating was uniform and showed cauliflower-like microstructure. It had high thermal stability (up to 400℃) and could be used for at least 180 times of solid-phase microextraction (SPME) without decrease in extraction performance. Furthermore, it presented high extraction capacity for the antidepressants due to the hydrogen bond and π-π interaction between the analytes and the coating. Under optimized conditions, good linearity (R>0.9958), wide linear range (0.01-50 μg/L) and low limits of detection (4.25-6.25 ng/L) were achieved for these analytes. The relative standard deviation was less than 5.3% for five successive measurements with one fiber, and the relative standard deviations for fiber-to-fiber were 4.8%-6.5% (n=5). The SPME-GC method was applied to the determination of lake water, with recoveries of 93.6%-109%.