Plunger-in-needle solid-phase microextraction with graphene-based sol–gel coating as sorbent for determination of polybrominated diphenyl ethers

A solid-phase microextraction (SPME) device, assembled with a commercially available plunger-in-needle microsyringe, with the plunger coated with graphene via a sol–gel approach, was developed for the gas chromatographic–mass spectrometric determination of polybrominated diphenyl ethers (PBDEs) in environmental samples. This is the first application of graphene-based sol–gel coating as SPME sorbent. Parameters affecting the extraction efficiency were investigated in detail. The new coating exhibited enrichment factors for PBDEs between 1378 and 2859. The unique planar structure of graphene enhanced the π–π interaction with the aromatic PBDEs; additionally, the sol–gel coating technique created a porous three-dimensional network structure which offered larger surface area for extraction. The stainless steel plunger provided firm support for the coating and enhanced the durability of the assembly. The plunger-in-needle microsyringe represents a ready-made tool for SPME implementation. Under the optimized conditions, the method detection limits for five PBDEs were in the range of 0.2 and 5.3 ng/L (at a signal/noise ratio of 3) and the precision (% relative standard deviation, n = 5) was 3.2–5.0% at a concentration level of 100 ng/L. The linearities were 5–1000 or 10–1000 ng/L for different PBDEs. Finally, the proposed method was successfully applied to the extraction and determination by gas chromatography–mass spectrometry of PBDEs in canal water samples.