Detection of Biologically Important Compounds in Flowing Aqueous Streams by Surface-Enhanced Raman Spectroscopy at a Silver Electrode

Abstract

Flow-injection analysis has been utilized to generate surface-enhanced Raman spectra of pyridine, adenosine, and adenosine 3′ monophosphate. These biologically important compounds have been recorded in a 10-μL spectroelectrochemical flow cell while under flowing conditions. Charge-coupled-device detection and low-power Ar⁺ laser excitation allowed an 1800-cm⁻¹ region to be observed with 10-s integration times. A computer-controlled potential waveform which efficiently adsorbs and desorbs the analytes at the electrode surface is described. The effects of the quantity of anodic charge passed during the ex situ and in situ roughening of the silver electrode on the SERS intensity are discussed. The limit of detection for 50-μL injections of adenosine under true dynamic conditions is less than 800 pmol. The technique yields both quantitative data and structural fingerprinting information for analytes eluting through the cell.