Polyethyleneimine-modified porous aromatic framework and silane coupling agent grafted graphene oxide composite materials for determination of phenolic acids in Chinese Wolfberry drink by HPLC.

A simple method for the determination of phenolic acids in Chinese Wolfberry drink based on polyethyleneimine modified porous aromatic framework and graphene oxide composite sorbent for pipette-tip solid-phase extraction was developed. Porous aromatic framework and raphene oxide composite materials were grafted by silane coupling agent (3-Chloropropyl)-trimethoxysilane. The modified materials were characterized by five kinds of characterization. Experimental results showed that the prepared p-phenylenediamine, cyanuric chloride, and graphene oxide composite material had a loose structure combined with the framework which improved hydrophobicity, and polyethyleneimine to increase the selectivity with the targets. The parameters of the pipette-tip solid-phase extraction procedure including the amount of sorbents, volumes and types of washing solvents and elution solvents were optimized to achieve optimal extraction efficiency. Good linearity of best material was achieved in the range of 0.1-400 µg/mL with correlation coefficient of chlorogenic acid (0.9994), caffeic acid (0.9997), and ferulic acid (0.9998). Recoveries between 93.5 and 102.3% were obtained at three spiked levels with relative standard deviation ≤3.1%. The proposed method was successfully applied for the determination of phenolic acids in Chinese Wolfberry drink sample.