WWRC 95-04
SERS Surface Modified with a 4-(2-Pyridylazo) Resorcinol Disulfide Derivative: Detection of Copper, Lead, and Cadmium
Abstract
We have developed a surface-enhanced Raman spectroscopic
technique for the determinadon of Pb2+, Cd2+, and
Cu2+ concentration using a 4-(2-pyridylazo)resoremol
(PAR) coating modified with a disulfide. The disulfide
provided a strong anchor to a roughened silver substrate.
Atomic specificity was demonstrated by the distinct spectral
changes that occurred through the interaction of Pb2+,
Cd2+, and Cu2+ ions with the indicator. The absorption
of these metals by the coating was followed with SERS and
could be fit to a Frumkin isotherm. Langmuirian behavior
was not observed; this is most likely due to the electrostatic
repulsions as the metal cations are absorbed. The
detection limits at pH 6 for Pb2+, Cd2+, and Cu2+ were
522,50.3, and 1.49 ppb, respectively. Flow experiments
using an optical fiber probe indicated instantaneons
response to changes in metal concentration.
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