Quartz crystal microbalance with β-cyclodextrin/TiO2 composite films coupled with chemometrics for the simultaneous determination of urinary 1- and 2-naphthol

A novel sensitive method was presented for the simultaneous determination of 1-naphthol (1-NAP) and 2-naphthol (2-NAP) in human urine samples. This method is based on the combination of the high sensitivity of quartz crystal microbalance (QCM) and excellent predictive ability of chemometrics. Nanocrystalline TiO2 films were used as substrates for immobilizing β-cyclodextrin (β-CD) onto the QCM surface. The sensing layer consisting of β-CD and nanocrystalline TiO2 particles was characterized by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG) and IR spectroscopy. In the Britton–Robinson (B–R) buffer solution of pH 6.37, frequency shift (ΔF) of the QCM was directly proportional to the concentration of 1-NAP and 2-NAP as 1.0 × 10−6 to 1.3 × 10−4 mol L−1, and 1.0 × 10−6 to 1.2 × 10−4 mol L−1, respectively. The correlation coefficients were 0.993 for 1-NAP, and 0.990 for 2-NAP. The limits of detection (LOD) were found to be 8.362 × 10−7 mol L−1 for 1-NAP and 2.146 × 10−7 mol L−1 for 2-NAP. The proposed method has been successfully applied for detecting 1-NAP and 2-NAP in human urine with a satisfactory result. The QCM with β-CD/TiO2 composite films coupled with chemometrics can lead to significant improvements in the sensor performance, and would be benefit to extend the scope of application of QCM and chemometrics.