FTW SERS probes with Ag NCs-GO composite structure excited by evanescent wave for in situ detection of permethrin.

BACKGROUND

Permethrin is a pesticide used to kill insects, and once used in excess, it poses a great threat to the environment and human health, therefore, it is necessary to realize the rapid and accurate detection of permethrin. Fiber optic surface enhanced Raman scattering (SERS) probes have the advantages of small volume and can be used for remote monitoring, which have great potential for application in achieving in-situ detection of pesticide residues.

RESULTS

Fiber taper waist (FTW) SERS probes modified by silver nanocubes-graphene oxide (Ag NCs-GO) composite structures were prepared for in situ detection of permethrin in lake water. Evanescent wave was used to excite SERS signals from Ag NCs-GO composite substrates, which was designed to enhance signals through expanded excitation light-analyte contact area. Ag NCs can provide stronger hot spots, and GO further enhances the sensitivity of SERS through electron transfer and improves the stability of the detection. The detection limit of prepared FTW SERS probe for Rhodamine 6G (R6G) was calculated to be 8.5 × 10 M and RSD were all below 5 % using the drop-casting method. The in-situ detection limit of R6G and permethrin in water was tested to be 10 M and 10 M, respectively.

SIGNIFICANCE

This work utilizes fiber optic evanescent waves to excite SERS signals, and adopts a special FTW structure and SERS substrates to achieve good performance. The synergistic enhancement of electromagnetism and chemistry is realized while increasing the contact area, which improves the sensitivity of in situ detection of the pesticide residue permethrin. It Promotes the application of fiber optic SERS sensors in pesticide residue detection.