Novel fabrication of silver-coated glass capillaries for ready SERS-based detection of dissolved chemical species

A novel method to deposit a highly surface-enhanced Raman scattering (SERS) active silver film onto the inside surface of a glass capillary is developed. Firstly, Ag sol was synthesized by the reaction of AgNO3 with poly-(ethylenimine) (PEI), and then toluene and benzenethiol (BT) were added into the sol. The mixture was flowed through the glass capillary to obtain the SERS-active Ag film-coated glass capillary. The SERS activity of the Ag-coated capillary was dependent on the amount of PEI and BT used. In addition, BT could be easily desorbed from the Ag surface by treating it with a borohydride solution, maintaining the initial SERS activity. The SERS enhancement factor at 632.8-nm excitation was estimated to be on the order of 10(6). The detection limits of adenine and dipicolinic acid were then as low as 1.0x10(-8) and 1.0x10(-7) M, respectively, based on an S/N ratio of 3. This clearly suggests that the Ag-coated capillary is an invaluable device for the analysis of effluent chemicals by SERS.