A simple filter-based approach to surface enhanced Raman spectroscopy for trace chemical detectionFunding for this work was provided by the National Institute for Biomedical Imaging and Bioengineering (5K25EB006011). The authors also acknowledge the support of the Maryland NanoCenter and its NispLab for the use of the Hitachi SU-70 Analytical UHR FEG-SEM. The NispLab is supported in part by the NSF as a MRSEC Shared Experimental Facility

We demonstrate an extremely simple and practical surface enhanced Raman spectroscopy (SERS) technique for trace chemical detection. Filter membranes first trap silver nanoparticles to form a SERS-active substrate and then concentrate analytes from a mL-scale sample into a L-scale detection volume. We demonstrate a significant improvement in detection limit as compared to colloidal SERS for the pesticide malathion and the food contaminant melamine. The measured SERS intensity exhibits low variation relative to traditional SERS techniques, and the data can be closely fit with a Langmuir isotherm. Thus, due to the simple procedure, the low-cost of the substrates, the quantitative results, and the performance improvement due to analyte concentration, our technique enables SERS to be practical for a broad range of analytical applications, including field-based detection of toxins in large-volume samples. We report a simple and practical surface enhanced Raman spectroscopy technique for trace chemical detection, demonstrating a significant improvement in detection limit as compared to colloidal SERS for malathion and melamine.