Development of a headspace solid-phase microextraction-surface-enhanced Raman scattering approach to detect volatile pesticides

By coupling headspace solid-phase microextraction (HS-SPME) with surface-enhanced Raman scattering (SERS), a facile and rapid method was developed for the detection of organophosphorus insecticides (phorate and isocarbophos) and organic sulfur bactericide (ferbam) in the vapour phase. Two types of SPME fibres based on stainless steel wires coated with gold (Au) nanoparticles were prepared. The fibre (Fibre II) prepared by an etching approach showed better sensitivity than did the fibre (Fibre I) prepared using a layer-by-layer self-assembly method. The Raman spectra of phorate, isocarbophos, and ferbam obtained from Fibre II showed stronger and clearer characteristic peaks compared with those from Fibre I, at 634, 1,043, and 1,380 cm(-1), respectively. It was found that the Raman intensity of phorate adsorbed on the Fibre II was nearly three times as high as that on Fibre I at 634 cm(-1), whereas the Raman intensity of isocarbophos was around 10 times at 1,043 cm(-1) and ferbam was approximately four times at 1,380 cm(-1). Using Fibre II, we were able to detect vapour-phase phorate, isocarbophos, and ferbam at concentrations as low as 0.02, 0.02, and 0.05 ppm, respectively, as well as their mixture. This approach can be simply extended to detect a wide range of volatile organic compounds and shows potential as an easier and faster alternative to gas chromatography methods for studying volatile chemicals in some cases.