Graphene oxide (GO)/graphene (GN) nanosheets were coated onto the poly(glycidyl methacrylate-ethylene dimethacrylate) monolithic bed synthesized inside the capillary in order to prepare a promising polymer monolith microextraction (PMME) material (GO/GN@poly(GMA-EDMA)). Various techniques, including Fourier transform infrared spectroscopy, atomic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy, were employed to characterize the synthesized GO/GN@poly(GMA-EDMA) monoliths, confirming that GO/GN was effectively functionalized on the poly(GMA-EDMA) monolithic materials. Furthermore, a new method was developed for the analysis of sarcosine (identified as a potential prostate cancer biomarker) using PMME coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under the preoptimized conditions, the monolithic column afforded satisfactory enhancement factor (32-fold) and low limits of detection (1.0 ng mL(-1)) were obtained. In comparison to several other commercialized solid phase extraction adsorbents, GN@poly(GMA-EDMA) monoliths exhibited excellent performance with recoveries of sarcosine approaching 93% with relative standard deviations less than 11.5%.

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Ionic liquid (IL) based dispersive liquid-liquid microextraction (DLLME) with back-extraction coupled with capillary electrophoresis ultraviolet detection was developed to determine four phenolic compounds (bisphenol-A, β-naphthol, α-naphthol, 2, 4-dichlorophenol) in aqueous cosmetics. The developed method was used to preconcentrate and clean up the four phenolic compounds including two steps. The analytes were transferred into room temperature ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate, [C(8) MIM][PF(6) ]) rich-phase in the first step. In the second step, the analytes were back-extracted into the alkaline aqueous phase. The effects of extraction parameters, such as type and volume of extraction solvent, type and volume of disperser, extraction and centrifugal time, sample pH, salt addition, and concentration and volume of NaOH in back-extraction were investigated. Under the optimal experimental conditions, the preconcentration factors were 60.1 for bisphenol-A, 52.7 for β-naphthol, 49.2 for α-naphthol, and 18.0 for 2, 4-dichlorophenol. The limits of detection for bisphenol-A, β-naphthol, α-naphthol and 2, 4-dichlorophenol were 5, 5, 8, and 100 ng mL(-1), respectively. Four kinds of aqueous cosmetics including toner, soften lotion, make-up remover, and perfume were analyzed and yielded recoveries ranging from 81.6% to 119.4%. The main advantages of the proposed method are quick, easy, cheap, and effective.