A NEW SPECTROELECTROCHEMICAL CELL FOR FLOW-INJECTION ANALYSIS AND ITS APPLICATION TO THE DETERMINATION OF FE(II) DOWN TO THE FEMTOMOL LEVEL BY SURFACE-ENHANCED RESONANCE RAMAN-SCATTERING (SERRS)

A spectroelectrochemical cell that uses surface-enhanced Raman scattering (SERS) for detection in flow injection analysis (FIA) is presented. The SERS-active surface is generated in situ by the electrochemical deposition of a silver film on a glassy carbon electrode. The electrode surface can be cleaned and renewed in situ between consecutive analytical determinations of adsorbates on the silver layer by anodic stripping of the used film and the deposition of a new one. Comparison with a flow cell, using a bulk silver electrode shows that, depending on the analyte, the silver electrode surface cannot be cleaned in situ. The potential applicability of the cell was demonstrated by determining Fe(II) in the form of [Fe(bipy)3]2+ (bipy = 2,2'-bipyridine) adsorbed on the silver-coated glassy carbon electrode. Iron has been detected at concentrations as low as 10(-9) M for an injected volume of 130 mul (femtomols of iron). Calibration curves were established in the concentration range from 10(-9) to 10(-5) M. The relative standard deviation of determination of Fe(II) at the 10(-9) M level was 10%.