Dual‐wavelength spectrophotometric determinations of copper and its composition of the complex with eriochrome blue black R

Abstract

AbstractCopper has been determined by a modified dual‐wavelength spectrophotometric (DWS) method, using the reaction of CuII with eriochrome blue black R (EBBR) at pH 12, which is sensitive and selective in the presence of both pentadecyltrimethylammonium bromide (PTMAB) and ascorbic acid. The modified DWS can completely eliminate the effect of excess EBBR in its CuII solution and give the real absorbance of the produced chelate of CuII with EBBR, with increased analytical sensitivity and decreased error. The composition of the complex of CuII with EBBR can be determined easily and accuratively. Beer's law is obeyed over the concentration range of 0‐1.60 mg Cu per 1 and the true molar absorbance of chelate Cu(EBBR)2 at 550 nm has been computed as 1.80 · 104 · mol−1 · cm−1. The detection limit of Cu is 0.04 mg. This method has been applied for the determination of trace amounts of copper in waste water with satisfactory results.