Carbon nanospheres covalently modified with polydimethylsiloxane on a porous sol–gel support for use in headspace solid-phase fiber microextraction of BTEX

Abstract

Carbon nanospheres were covalently modified with hydroxy-terminated poly(dimethylsiloxane) to give a new sorbent (referred to as CNS-PDMS). It was applied as the extraction phase in a sol–gel based solid-phase microextraction fiber for benzene, toluene, ethylbenzene and o-xylene (BTEX). Due to the unique properties of CNS and the performance of the sol–gel coating technology, this fiber possesses a porous surface, a long operational lifespan (at least 200 times), and high thermal stability (up to 350°C). Its extraction capability is higher than that of commercial polydimethylsiloxane (PDMS) and polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibers. Following desorption, the BTEX were quantified by GC with FID detection. The detection limits (at an S/N ratio of 3) range from 1 to 10 pg mL−1, and the limits of quantification (at an SNR of 10) are between 3 and 30 pg mL−1. The repeatability of a single fiber (for n = 5) is between 3.9 and 6.3%, and the fiber-to-fiber reproducibility (for n = 3) ranges from 5.3 to 8.2%, respectively. The relative recoveries in the real water samples ranged from 92.5% to 99.5%. The results demonstrate that the method is highly effective for analyzing BTEX in water samples.