The ultratrace detection of crystal violet using surface enhanced Raman scattering on colloidal Ag nanoparticles prepared by electrolysis

Highly active, stable and affordable surface enhanced Raman scattering (SERS) substrates were obtained by electrolyzing a mixture of AgNO3 (4 x 10(-4) mol/L) and Na3C6H5O7 center dot H2O (6 x 10(-5) mol/L) for 1, 2,3 and 4 h at 7 V. With crystal violet (CV) as a test molecule, a portable Raman spectrometer with 785 nm laser excitation was employed to carry out the SERS detection. Colloidal Ag nanoparticles prepared by electrolyzing for 3 h with the particle size of (65 +/- 17) nm is a perfect SERS substrate for the ultratrace detection of CV, which displayed an enhancement factor of ca. 1.3 x 10(8) and the detection limit of CV is down to ca. 10(-15) mol/L (ca. 10(-4) ppb) with 10(-1) mol/L KBr as aggregating agent. Thus, this SERS substrate will provide a hopeful foreground in ultratrace detection. Meanwhile, it will provide a possibility to bring Raman analysis out of the laboratory to process in situ, real-time detection and identification. (C) 2009 Published by Elsevier B.V. on behalf of Chinese Chemical Society.