Development of molecularly imprinted polymers-surface-enhanced Raman spectroscopy/colorimetric dual sensor for determination of chlorpyrifos in apple juice

- A AgNPs- based colorimetric/SERS dual sensor to determine CPF was developed.
- MIPs were synthesized by bulk polymerization to extract CPF from apple juice.
- CPF in apple juice at concentrations ≥5 mg L−1 was detected by naked eyes.
- UV and Raman spectroscopies quantified CPF in apple juice at 0.1 and 0.01 mg L−1.
- Rapid determination of trace level of CPF in apple juice was achieved (<25 min).

Chlorpyrifos (CPF), an organophosphate insecticide, is widely identified in fruit juices. In this study, a novel molecularly imprinted polymers-surface-enhanced Raman spectroscopy (MIPs-SERS)/colorimetric dual sensor was developed to determinate CPF in apple juice. MIPs were synthesized using bulk polymerization to rapidly and selectively adsorb and separate CPF from apple juice. A colorimetric method was developed based upon color changes of synthesized silver nanoparticles (AgNPs) by interacting with CPF, while SERS spectra were directly collected by illuminating the aggregated AgNPs with Raman laser. Colorimetric method rapidly screened and semi-quantified CPF in apple juice ≥5 mg L−1 by naked eye, or accurately quantified CPF in apple juice ranging 0.1-10 mg L−1 by UV-vis spectroscopy. Principle component analysis and partial least-squares regression models (RMSEC = 0.0453, R2-C = 0.9885) validated using SERS to further quantify CPF in apple juice at extremely low concentration (0.01 mg L−1). This MIPs-SERS/colorimetric dual sensor can rapidly (<25 min), accurately, and cost-efficiently determine CPF in apple juice and meet the worldwide regulation of maximum residue limit.