Rapid Analysis of Bitertanol in Agro-products Using Molecularly Imprinted Polymers-Surface-Enhanced Raman Spectroscopy

Abstract

In this work, we first reported molecularly imprinted polymers-surface-enhanced Raman spectroscopy (MIP-SERS) for rapid detection and quantification of bitertanol in cucumber and peaches. In order to remove interference-mitigation effects and avoid template leakage, MIPs were successfully synthesized based on triadimefon molecules as the dummy template, methacrylic acid (MAA) as a functional monomer, trimethylolpropane trimethacrylate (TRIM) as a cross-linker, and 2,2-azobis-isobutyronitrile (AIBN) as an initiator. Static adsorption experiments and Scatchard analysis were then conducted and results showed that the synthesized MIPs could rapidly and selectively adsorb and separate bitertanol from cucumber and peaches due to their predetermined recognition sites. The capacity of MIPs for absorbing bitertanol (∼ 2.21 mg/g) was approximately 1.5 times that of non-imprinted polymers (NIPs) (∼ 1.55 mg/g). Gold nanoparticles (AuNPs) synthesized by sodium citrate reduction method were validated as a suitable SERS colloid for enhancing Raman signals. SERS spectral peaks (760, 985, 1190, and 1279 cm−1) were used to develop quantitative analysis based on partial least-squares regression (PLSR) for bitertanol in cucumber and peaches. The LODs for this method were 0.041 and 0.029 mg/kg in cucumber and peaches, respectively. The entire analysis process required 15 min or less. More importantly, the MIP-SERS system provided not only a rapid, sensitive, and reliable method for bitertanol detection, but also a routine for overcoming the interference-mitigation effects in the SERS technology.