Surface Enhanced Raman Scattering Spot Tests: A New Insight on Feigl’s Analysis Using Gold Nanoparticles

• Published in: Analytical chemistry (Washington) Vol. 82; no. 22; pp. 9146 - 9149
• Main Authors: Grasseschi, Daniel, Zamarion, Vitor M, Araki, Koiti, Toma, Henrique E
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.11.2010
• Subjects: Analytical chemistry; Chemistry; Exact sciences and technology; Gold; Ions; Molecules; Nanoparticles; Scattering; Spectrometric and optical methods; Gold; Spot test; Nanoparticle; Mercury II; Citrate; Dithizone; Metal ion; Transition metal; Filter paper; Probe; Heavy metal; Mercury ion; Molecules; Signal; Surface Enhanced Raman Spectrometry; Reagents; Raman spectrometry; Detection; Monitoring
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac102238f

Traditional Feigl’s spot tests can be greatly improved with the aid of gold nanoparticles and Raman probes, by monitoring the changes in the surface enhanced Raman scattering (SERS) of the analytes directly applied on a filter paper previously impregnated with the selective organic reagent. As a proof of concept, diphenylthiocarbazone (dithizone) was treated with citrate stabilized gold nanoparticles and employed in paper spot tests for a variety of transition and heavy metal ions. Below 10−5 mol L−1, only mercury(II) ions were able to displace the dithizone molecules from the “coordination shell” of the gold nanoparticles, leading to a systematic decay of the Raman signals. Because of the huge enhancement of the dithizone vibrational peaks, the SERS spot tests allowed the detection of picograms of Hg2+ ions.