A NOVEL METHOD FOR DETECTION OF CHLORPYRIFOS BY COMBINING QUANTUMM DOTS LABELED MOLECULARLY IMPRINTED POLYMERS WITH FLOW CYTOMETRY

We synthesize quantum dots labeled molecularly imprinted polymers (MIPs) which can act as a fluorescent probe for the selective and sensitive detection of chlorpyrifos by flow cytometry. ¹

The uniform-sized fluorescent MIPs were prepared by one-step swelling and suspension polymerization, while chlorpyrifos, methacrylic acid, ethylene glycol dimethacrylate and oil-soluble CdSe/ZnS quantum dots were using as carrier, template molecule, functional monomer, cross-linker and fluorophor respectively. The MIPs have a large specific surface area, which makes them suitable for binding template molecules. The morphology, adsorption dynamics, binding ability and selectivity of quantum dots labeled MIPs were evaluated.

Based on this fluorescence quenching phenomenon, a facile and direct fluorometric quantitative method was successfully developed for the chlorpyrifos in aqueous media without any preconcentration processes. In the presence of different concentrations of chlorpyrifos, a gradual decreasing of the fluorescence intensity of quantum dots labeled MIPs could be clearly identified by flow cytometry. The corresponding fluorescence histogram of quantum dots labeled MIPs in the presence of different concentrations of chlorpyrifos, and a gradual decrease in the peak fluorescence can be clearly identified, a linear range of 0.02-0.2 mg/L was obtained. The precision of the method is 1.5%-6.8% (n=7), and the limit of detection was 0.01 mg/L.

This method was used to analyze chlorpyrifos in tap water sample. After the water samples were collected and filtered, the determination was carried out with the calibration curve method. There is no chlorpyrifos detected in the water samples. After adding 0.03 mg/L of chlorpyrifos in the tap water sample and repetitively measuring 3 times, the detected chlorpyrifos’ concentration was 0.028 mg/L, the recovery rates were 92.8 ± 4.8%.

Compared to conventional analytical methods, this hyphenated technique can provide improvements with respect to reduced analysis time, and simplified manipulation. The whole detection process can be accomplished within 2 hours including pretreatment. There are some advantages of this method, including rapid readout as well as high throughput, quantum dots labeled MIPs amplification of the optical signal using single excitation source, low cost, and low toxicity. These distinct features make this proposed format a promising prescreening tool for monitoring environmental contamination in different sample types.

References:

1. Zhang Hong, Wang Pingmei, Zhou Qiang, Wang Yanhong (2018) A Novel Method for the Detection of Chlorpyrifos by Combining Quantum Dot-labeled Molecularly Imprinted Polymer with Flow Cytometry. Analytical Letters 51, 6:921-934