In situ homogeneous formation of Au@AgNPs for the rapid determination of formaldehyde residues by surface-enhanced Raman spectroscopy coupled with microhydrodistillation

The reaction of formaldehyde (HCHO) with the solution containing Au nanoparticles and [Ag(NH3)2]+ through Tollens’ reaction is described to form Au@Ag nanoparticles (Au@AgNPs), which are used as a SERS enhancement material. A minimized hydrodistillation device with air condense is designed to obtain a clean aqueous background for SERS analysis and simplified pretreatment process. A good linear relationship is found between the SERS signals and...