A polypyrrole film coated by electrochemical polymerization on a platinum surface has been demonstrated as an electrochemical detector for the flow-through analysis of ionic substances. Anion detection is based on the doping and conductivity properties of the conductive polymer. Anions are detectable at concentrations as low as 1 mu M with the use of a glycine solution as a mobile phase solution. The potential of the electrode is controlled at plus 0. 6 V (versus Ag/AgCl reference electrode) during the analysis. With the use of a polymer electrolyte solution as a mobile buffer solution, anions are detected at concentrations as low as 100 mu M.