Determination of copper ions in waters by electrochemical stripping chemiluminescence analysis in situ

A novel stripping chemiluminescence (CL) method in situ has been developed which is a combination of selective stripping and CL detection in situ. This method consists of a concentration (pre-electrolysis) step, in which the analyte metal ion is reduced at a controlled potential whilst being deposited as the metal on a solid electrode placed in an electrogenerated chemiluminescence flow cell, a subsequent media exchange step and finally the stripping–CL step, in which the CL emission on the electrode surface is detected in situ when the CL reagent solution is delivered into the cell to react with the metal ion which has just been stripped by oxidization. The concentration of analyte is quantified by CL intensity. Copper ion as a representative analyte was investigated using constant potential stripping and CL detection of a luminol–copper(II)-cyanide system. The response to the concentration of copper is linear in the range 0.040–40 µg dm–3 and an extremely low detection limit of 0.02 µg dm–3 can be achieved in a deposition time of 2 min. The method developed has been applied successfully to the determination of copper in water samples. The method shows excellent selectivity and sensitivity compared with the associated CL and square wave anodic stripping voltammetry method.