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

Abstract 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 TiO 2 films were used as substrates for immobilizing β-cyclodextrin (β-CD) onto the QCM surface. The sensing layer consisting of β-CD and nanocrystalline TiO 2 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 (Δ F ) 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/TiO 2 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.