Flow injection chemiluminescence method for the selective determination of chromium(III)

Abstract

Flow injection (FI) has been applied to the determination of Cr^III in water and food samples. The method is based on measurement of the light emitted from the Cr^III-catalysed oxidation of luminol by H₂O₂. The apparatus consists of an FI system with a flow cell suitable for chemiluminescence detection. The flow cell, situated near the photodetector, is a coiled tube made from transparent polytetrafluoroethylene. The typical signal is a narrow peak, the height of which is proportional to the light emitted and, therefore, to the concentration of Cr^III. The detection limit is 0.01 ppb and the linear range extends up to 6 ppb. The concentrations of the reagents, the pH and the flow rates were optimized. Interferences by several metal ions were examined, and the system was shown to possess a high selectivity. The method was successfully applied to the determination of Cr^III in water and food samples.