Graphene oxide based in-tube solid-phase microextraction combined with liquid chromatography tandem mass spectrometry for the determination of triazine herbicides in water.

A novel in-tube solid-phase microextraction method based on a graphene oxide coated column was developed for the determination of triazines in waters. This column was prepared by the covalent modification of monolayer graphene oxide sheets onto the inner wall of a fused-silica capillary. Scanning electron microscopy showed that the thickness of the graphene oxide coating was ∼30 nm, with a porous, wrinkled membrane-like structure. Its performance was evaluated through the extraction of triazines in water. Results showed that the coating was stable for at least 100 replicate extractions, and variety of multi-columns was less than 10%. Flow rate, loading volume, pH, and ionic strength of samples played an important effect on the extraction. The high extraction efficiency was mainly attributed to π-π stacking and hydrogen bonding interactions. The in-tube solid-phase microextraction was used in the determination of triazines with liquid chromatography and tandem mass spectrometry, and the detection limits were 0.0005-0.005 μg/L for five triazine compounds. Further, the method was applied to the analysis of triazine herbicides in real samples including tap water, sea water, and river water, and the recoveries were 82.8-112.0, 85.4-110.5, and 81.6-105.9%, respectively, with RSDs of 2.7-7.1%.