Automated Determination of Chromium (VI) in Tannery Effluent Using Flow Injection Analysis with an Optical Flow Cell and Detector

Determination of hexavalent chromium (Cr (VI)) in tannery effluent is an important analytical objective for environmental monitoring and assessment. Here, a simple, accurate, and sensitive automated flow injection analysis (FIA) method is proposed in this paper. The procedure is based on a highly selective reaction between Ponceau S and Cr (VI) under acidic condition. The absorbance of the complex compounds was measured using an optical detector at 505 nm. The chemical factors and FIA variables that affect the system were fully discussed and optimized via univariate experimental design. Under the optimal conditions, a linear dynamic range of 0.1–3.0 mg/L with a satisfactory determination coefficient ( R 2 ) of 0.9996 was obtained. The detection limit and relative standard deviation were 0.08 mg/L and 2.27%, respectively. Finally, the method was successfully applied to determine Cr (VI) in field samples of tannery effluent and the results have no significant difference comparing with one official method, indicating this FIA method could be practically promising for determination of Cr (VI) in tannery effluent.