Sensitive detection of imidacloprid at ultra-trace level utilizing ratiometric surface-enhanced Raman scattering platform based on C60 and rhodamine 6G

A novel ratiometric surface-enhanced Raman scattering (SERS) platform had great potential to sense imidacloprid with high sensitivity and broad quantitative range. Herein, the double reporting molecules—C 60 and rhodamine 6G (R6G)—were adopted to develop a ratiometric SERS platform. Apart from that, the bands of C 60 and of R6G coexisted unambiguously in the spectrum of the mixture of C 60 and R6G with an appropriate mol ratio of C 60 and R6G (100:1). The possible imidacloprid analysis principle is the interference of imidacloprid on the binding between C60 and R6G, which thus leads to the change of the Raman characteristic peak intensities of C60 and R6G. Imidacloprid could be detected at ultra-trace level due to collected signal of R6G, instead of the Raman signal of imidacloprid itself. The SERS signal ratio between the peaks at 485 cm −1 and 1358 cm −1 ( I 485/1358 ) was used for the quantification of imidacloprid. Under the optimal conditions, the limit of detection of the presented method was 1 nmol/L (0.256 μg/L) ( S / N = 3). Notably, the linear range of the proposed method from 10 –8 to 10 –4 mol/L (2.56 μg/L–25.6 mg/L), which was broad. Imidacloprid spiked in mandarin orange juice was analyzed via the developed method successfully with a recovery ranging of 96.7–116.2% and a relative standard deviation ranging of 6.5–9.8%, respectively. That is to say, the ratiometric SERS platform, as a convenient and sensitive sensor, may have a promising application in imidacloprid determination.