Multiple weak interaction-assisted SERS detection platform for triadimefon.

In this paper, a surface enhanced Raman spectra (SERS) detection platform for the widely used pesticide of triadimefon (TDF) is described. TDF is difficult to connect to the gold/silver SERS substrate, but the optical properties of the probe molecule 4-mercaptobenzoic acid (4-MBA), including the peak intensity and the peak position, are easily altered by the multiple weak interaction-assisted SERS detection platform. The limit of detection (LOD) of this method is 1.0 × 10-9 M, and the linear range is from 1.0 × 10-6 M to 1.0 × 10-9 M. The linear region is from 1.0 × 10-6 M to 1.0 × 10-9 M, described by the equation y = 884.01x + 2.24 with a correlation coefficient ( R2) of 0.9990. Interference of foreign metal ions with higher concentrations than common mineral water is too weak to the determination. Furthermore, physical insights into the phenomena and the detection mechanism were obtained and investigated theoretically. The preferential conformation of the complex and reduced density gradient (RDG) calculation results indicated that the interactions between TDF and 4-MBA consisted of multiple weak interactions through two hydrogen bonds and one van der Waals interaction. The intermolecular interaction was negative for the charge transfer from the SERS substrate to the probe molecule; thus, the peak intensity decreased. TDF interacts directly with the carboxyl of the probe molecule and consequently has an effect on the ring vibrations. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]