Molecularly imprinted polymers immobilized on graphene oxide film for monolithic fiber solid phase microextraction and ultrasensitive determination of triphenyl phosphate

Triphenyl phosphate (TPhP), a typical model of organophosphorus flame retardants (OPFRs), has been regarded as emerging environmental contaminants of health concern. In this study, TPhP molecularly imprinted polymers immobilized on graphene oxide (GO) film (TPhP-MIPs/GO) monolithic fiber for direct immersion solid phase microextraction (DI-SPME) was fabricated and evaluated. Compared with TPhP molecularly imprinted polymers (TPhP-MIPs) monolithic fiber, TPhP-MIPs/GO fiber had bigger extraction capacity, stronger hydrophilicity and faster mass transfer rate. Furthermore, TPhP-MIPs/GO fiber displayed excellent selectivity for TPhP among its structure analogues. It was thermally stable up to 320 °C so that it can withstand the high temperature of gas chromatography (GC) injection port for desorption and detection by flame photometric detector (FPD). Under optimal conditions, TPhP-MIPs/GO-SPME-GC/FPD method was developed by yielding satisfactory ultralow limit of quantification (0.4 ng L^-1); linearity (≥0.99), good intra- and inter-day precision for a single fiber and fiber-to-fiber reproducibility. The method was applied for the determination of TPhP in environmental water and the relative recoveries were found to be in the range from 70 to 110%. TPhP was detected in three out of four environmental water samples at concentration levels from 0.04 to 0.12 ng mL^-1, illustrating light pollution of TPhP in most environmental water.