A novel quartz crystal microbalance sensor array based on molecular imprinted polymers for simultaneous detection of clenbuterol and its metabolites

For the rapid and robust detection of both parent clenbuterol (CLB) and its metabolites in swine urine samples, a novel quartz crystal microbalance (QCM) sensor array for CLB detection based on molecularly imprinted polymers (MIPs) was developed in this investigation. At first, clenbuterol and the structural analogs of its metabolites, 4-Aminohippuric acid (AHA) and 4-hydroxymandelic acid (HMA), were chosen as molecular templates. Through computational molecular modeling, the optimum ratio between the functional monomer and molecular template was selected. The surface imprinting method was applied to modify QCM electrode surface to graft a thin MIP film. The grafting polymer was characterized by Fourier-transformed infrared spectrometry (FTIR) and atomic force microscopy (AFM), respectively. After then, an array system composed of three sensors was employed to test the responses with different solutions and the principal component analysis (PCA) was adopted to analyze the corresponding data. As a result, for the designed sensor to clenbuterol, a linear equation y=100.07x-722.96 (R-2=0.9928) was found between the sensor frequency shift OF and negative logarithm of clenbuterol concentration (-lgC). The limitation of detection (LOD) was 3.0 ng/mL, which is lower than the Codex Alimentarius Commission regulations residue limit 10 mu g/L. The corresponding data of the three template solutions were analyzed by PCA, obtaining 100% recognition. The result demonstrated the feasibility that the developed method could be applied to detect whether the livestock was feed with CLB nutrient redistribution agent by checking the urine samples.