Graphene oxide coated capillary for the analysis of endocrine-disrupting chemicals by open-tubular capillary electrochromatography with amperometric detection

A graphene oxide-coated capillary was fabricated by using 3-aminopropyltriethoxysilane as the cross-linking agent. It was used for the separation and detection of three endocrine-disrupting chemicals, including bisphenol A, 4-nonylphenol, and 4-octylphenol by capillary electrochromatography. Due to the hydrophobicity, hydrogen bonding, and π-π interaction between graphene oxide and the analytes, the three analytes could be well separated in pH = 11.0, 20 mmol/L Na₂B ₄O₇-NaOH/methanol mobile phase (50:50, v/v) within 950 s. After preconcentration, the detection limits were 6.7 × 10^-10, 3.3 × 10^-9, and 6.7 × 10^-10 mol/L (S/N = 3) for bisphenol A, nonylphenol, and octylphenol, respectively. The developed method was successfully applied to the determination of the above analytes in water samples. The satisfactory result demonstrated that the graphene oxide coated capillary used in capillary electrochromatography with amperometric detection was convenient to prepare, highly stable, and had good reproducibility.