SENSING OF TRACE COPPER-ION BY A SOLID-PHASE EXTRACTION SPECTROPHOTOMETRY USING A POLY(VINYL CHLORIDE) MEMBRANE CONTAINING BATHOCUPROINE

A new sensitive and selective spectrophotometric method for the determination of trace copper using a poly(vinyl chloride) membrane containing 4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline (bathocuproine) and o-nitrophenyl-octylether as the solid phase extraction medium. Copper(I) in an aqueous sample solution is trapped on the membrane with an anion species, picrate ion, to form copper(I)-bathocuproine-picrate complexes, and the copper complexes, i.e. copper(I), were concentrated in the membrane. The absorbance of the orange membrane was measured at 480 nm using a spectrophotometer, and the concentration of the copper was then calculated using a calibration graph, which expressed the relationship between the copper(I) concentration and the membrane absorbance after coloring for 10 min. The detectable concentration of copper in a sample solution was in the range of 1.5 x 10(-7)-4.3 x 10(-5)M. The reproducibility of the absorbances of membranes was 0.193 +/- 9.44 x 10(-3) with a 4.9% relative standard deviation on five repeated measurements for the sample containing 1.2 x 10(-5)M of copper(II) under the same experimental conditions.