Cyclic Flow Injection Analysis for Heavy Metal Ions Using Xylenol Orange

Abstract

Spectrophotometric determinations of heavy metal ions with xylenol orange (XO) have been carried out using cyclic flow injection analysis. A cation-exchanger mini-column (Amberlite IR124) was incorporated after a flow-through cell for the on-line regeneration of the used reagents and the accumulation of heavy metal ions. A solution of 1.0×10−5 M XO in 0.01 M acetate buffer (pH 5.0) in a single reservoir (100 mL) was continuously circulated, and sample solutions were injected into the stream. Cadmium(II), copper(II), iron(III), lead(II), zinc(II) and lanthanum(III) were sensitively monitored and determined. The regeneration and recycling of the XO reagent allowed as many as 50 repetitive determinations of heavy metal ions with the same 100 mL circulating reagent solution.