High reliable and robust ultrathin-layer gold coating porous silver substrate via galvanic-free deposition for solid phase microextraction coupled with surface enhanced Raman spectroscopy.

That intense demand for both high sensitivity and high reliability has been a key factor strengthening the surface enhanced Raman spectroscopy (SERS) in the analytical application, particular in the hyphenation with pre-concentration technique. Credible data acquisition and processing is very dependent on the stable and uniform performance of SERS-active substrate. Here, a reliable and uniform ultrathin-layer Au was proposed for protecting the porous Ag fiber (porous Ag@Au) and applied in the solid phase microextraction coupled with SERS. The Au layer was carefully deposited on porous Ag surface to form the uniform film by a galvanic-free displacement reaction. This coating endowed the substrate with high oxidation-resistance under heating and good durability in the atmosphere condition. The extraction and SERS performance of Nitrofurazone and Semicarbazide were investigated on this fiber, the bands at 1350 cm-1 and 1387 cm-1 were selected as the characteristic peaks for quantitative determination, respectively. This robust and sensitive substrate provide the high enhancement factor of 1.3 × 106 and low LOD of 5.1 ppb for the extraction and identification of Nitrofurazone compounds. Importantly, this work develops a versatile strategy for rapid detection of prohibited antibiotic and its marker residue in a complex matrix.