Sensors and Actuators B 241 (2017) 750–757 Contents lists available at ScienceDirect Sensors and Actuators B: Chemical jo u r nal homep age: www.elsevier.com/locate/snb Development of molecularly imprinted polymers-surface-enhanced Raman spectroscopy/colorimetric dual sensor for determination of chlorpyrifos in apple juice Shaolong Feng, Yaxi Hu, Luyao Ma, Xiaonan Lu ∗ Food, Nutrition and Health Program, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada a r t i c l e i n f o Article history: Received 1 August 2016 Received in revised form 23 October 2016 Accepted 27 October 2016 Available online 29 October 2016 Keywords: Molecularly imprinted polymers Raman spectroscopy Colorimetric Chlorpyrifos Food safety Chemometrics a b s t r a c t 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 poly- merization 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 com- ponent analysis and partial least-squares regression models (RMSEC = 0.0453, R 2 -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. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Chlorpyrifos (O,O-diethyl O-3,5,6-trichloropyridin-2-yl phos- phorothioate, CPF) is one of the most widely used organophosphate pesticides that can effectively inhibit acetylcholinesterase and block the signals travel between nerve cells. As a result, it causes the malfunction of central nervous system of the pests and eventually kills the pests [1]. CPF is commonly used in agriculture crops (e.g., corn, soybeans, fruits, etc.). According to the United States Environ- mental Protection Agency (EPA), CPF remains the most commonly used organophosphate pesticide for crops in the United States with an estimated annual consumption of 5–10 million pounds to be applied to over 50% apple crops during 2006–2012 [2]. CPF is moderately toxic to humans and considered as a neurotoxin and endocrine disruptor, and it is especially harmful to pregnant women and infants [1,3]. A recent study also reported an associ- ation between human exposure to CPF and the incidence of lung cancer [4]. Considering its toxicity and enormous application in agriculture, effective detection of CPF residues in agri-food prod- ucts is highly demanding. Traditional detection methods are based ∗ Corresponding author. E-mail address: xiaonan.lu@ubc.ca (X. Lu). upon high cost instruments, such as high performance liquid chro- matography coupled with photodiode array detector (HPLC-DAD) [5], liquid chromatography-mass spectrometry (LC–MS) [6], and gas chromatography-mass spectrometry (GC–MS) [7]. However, all these methods are laborious, time-consuming, and require large amount of organic reagents. Therefore, novel, simple, low-cost, and accurate analytical methods are highly demanded. Silver nanoparticles exhibit intense colors due to the surface plasmon resonance (SPR) phenomenon [8,9]. Under the irradiation of electromagnetic waves, the SPR effect will produce character- istic absorption peak, which depends upon the size and shape of the particles and the dielectric properties of surrounding medium and inter-particle distances [10]. Many factors can promote the aggregation of nanoparticles and cause SPR band shift to a longer wavelength [11]. The interparticle distance changes and subse- quently results in quantifiable red-shift or blue-shift of the UV–vis absorption, which is the basic principle of colorimetric sensing system [12]. Due to the rapid, sensitive, and easy-operational fea- tures, colorimetric-based detection methods have been extensively investigated as different colorimeter sensors to analyze various chemical and biological molecules [13–16]. However, the poor selectivity of colorimetric sensor has limited its application in com- plex sample matrices (e.g., foods) because numerous interferents may cause the aggregation of nanoparticles. Many studies were http://dx.doi.org/10.1016/j.snb.2016.10.131 0925-4005/© 2016 Elsevier B.V. All rights reserved.