On-line trace metal determination by pre-concentration on immobilized 8-quinolinol with flow recycling anodic stripping voltammetry

On-line enrichment of trace metals on an immobilized 8-quinolinol column has been combined with anodic stripping voltammetry. The experimental conditions, e.g., flow rate, medium composition, enrichment and deposition times were optimized. A new approach — flow recycling during the deposition step — enables an increase in the deposition time and, thus, the sensitivity without increasing the sample volume. The total duration of analysis using a chelate ion-exchange column combined with anodic stripping voltammetry can be decreased considerably because the analytical signals are proportional to the product of enrichment and deposition enhancements. It is shown that by using 5 min for enrichment and 5 min for recycling, the analytical signal will be enhanced about 50 times compared to an ordinary anodic stripping voltammetry with a deposition time of 10 min. The required sample volume is also reduced by a factor of two.