Fabrication of poly(3,4-ethylenedioxythiophene)-ionic liquid functionalized graphene nanosheets composite coating for headspace solid-phase microextraction of benzene derivatives.

A new poly(3,4-ethylenedioxythiophene)-ionic liquid (i.e. 1-hydroxyethyl-3-methyl imidazolium-bis[(trifluoromethyl)sulfonyl]imide) functionalized graphene nanosheets (PEDOT-IL/GNs) composite coating was electrodeposited on a stainless steel wire for headspace solid-phase microextraction. The coating showed porous folded and wrinkled structure and had large surface area due to the combined effect of PEDOT and IL/GNs. In addition, it displayed high thermal stability (up to 340 °C) and durable property (could be used for more than 200 times). The PEDOT-IL/GNs coating exhibited high affinity to benzene derivatives studied (i.e. toluene, 1,4-dimethylbenzene, 1,2-dimethylbenzene, 2-chlorotoluene, 1,3,5-trimethylbenzene and 1,4-dichlorobenzene) as they can interact through π-π and hydrophobic interactions. When they were extracted the enrichment factors ranged from 1901 (for 1,4-dichlorobenzene) to 3041 (for 1,4-dimethylbenzene). Coupled with gas chromatography-flame ionization detection, the benzene derivatives were extracted and determined. Wide linear ranges with 4 orders of magnitude (0.06-500 μg L(-1)) and low limits of detection (10.7-19.8 ng L(-1)) were achieved. The RSDs of chromatographic peak areas were <5.9% (n=5) and <7.5% (n=5) for single fiber and fiber-to-fiber, respectively. The method was applied to the determination of the benzene derivatives in real samples with acceptable recoveries from 82.3% to 108.3%.