SERS detection of food contaminants by means of portable Raman instruments

Surface-enhanced Raman scattering (SERS) has been emerging as a powerful tool for the detection of a variety of analytes due to its very high sensitivity and fingerprinting recognition capabilities. Technological progresses in the equipment for Raman analysis are contributing to its transition from a technically demanding research method to a more widely available analytical technique. In particular, the commercialization of portable or handheld instruments has opened up the possibility of performing in situ analysis. In this review, a selection of the SERS substrates that are expected to be more suitable for use in combination with portable instruments is presented: Substrates are compared, for example, in terms of performance, reproducibility, ease of fabrication, and surface area. Moreover, this paper provides a survey of the current diffusion of portable Raman instruments in the SERS detection of food contaminants: The investigation of several analytes is summarized (mainly toxins, virus, bacteria, pesticides, forbidden food dyes, and preservatives), reporting on the limits of detection and on the eventual coupling with concentration or separation techniques. A brief perspective on possible future developments of the SERS detection with portable instruments is also provided.