Detection of amoxicillin residues in egg extract with a molecularly imprinted polymer on gold microchip using surface plasmon resonance and quartz crystal microbalance methods

In this study, surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) sensors were prepared for the detection of amoxicillin from the commercial and local chicken eggs by using molecular imprinting technique. Amoxicillin imprinted poly(hydroxyethyl methacrylate-methacrylic acid) polymeric film was synthesized onto the surface of the SPR and QCM chips by ultra violet polymerization to determine lower concentrations of amoxicillin. Ellipsometry, contact angle analysis, and atomic force microscopy measurements were used for the surface morphology of the polymeric film layer. The ellipsometric thickness of AMOX imprinted and nonimprinted SPR and QCM chip surfaces were measured as 35 +/- 0.9 nm, 32.89 +/- 1.9 nm, 30 +/- 0.6 nm, and 28 +/- 0.22 nm, respectively. Contact angles of bare gold surfaces, AMOX imprinted SPR and QCM chip surfaces were measured to be as 82.3 degrees +/- 0.15, 79.2 degrees +/- 0.14, 75.01 degrees +/- 1.07, and 69.11 degrees +/- 0.89, respectively. The range of linearity was measured as 0.1 to 10 ng/mL for amoxicillin imprinted SPR and QCM sensors. The maximum residue limit of AMOX in eggs is at 10 mu g/kg in accordance with the Positive List System for Agricultural Chemical Residues in Foods. The response time for the test, including adsorption, desorption, and regeneration, was approximately 45 min. The limit of detections for SPR and QCM sensors were found to be 0.0005 and 0.0023 ng/mL, respectively. The reusabilities of amoxicillin imprinted SPR and QCM sensors were observed by the equilibration-binding-regeneration. Validation studies of the AMOX imprinted SPR and QCM sensors were performed by liquid chromatography-tandem mass spectrometry.