The determination of trace amount of Cr(VI) and As(V) in aqueous solution by UV-vis spectrophotometer assisted with preconcentration on a quaternary ammonium ion exchange fiber-in-tube

摘要

A simple and sensitive method was developed for the determination of Cr(VI) and As(V) using a microcolumn packed with quaternary ammonium ion exchange fiber for the preconcentration of trace amount of Cr(VI) and As(V) prior to their determination by UV-vis spectrophotometer. It was found that Cr(VI) and As(V) could be almost completely retained on ion-exchange fiber in the pH range of 5.0-6.5 and 3.5-5.0, respectively. With a mixture eluent of 5% (w/v) NH4Cl and 10% (v/v) NH3/H2O solution, they could be almost quantitatively eluted. Under the optimized conditions, the detection limits were 0.2 mu g L-1 for Cr(VI) and 0.8 mu g L-1 for As(V) with enrichment factors of 96.5 and 95.3, respectively. The relative standard deviations for nine replicate determinations at 5 and 10 mu g L-1 for Cr(VI) and As(V) were 2.2 and 3.4%, respectively. These results proved that the proposed method had a potential in the analysis of trace metal ions with good accuracy in real samples.