Solid-phase spectrophotometric determination of trace copper after collection as its bathocuproinedisulfonate chelate anion on chitin

Abstract

A collection method for anionic species on protonated chitin has been applied to the solid-phase spectrophotometric determination of trace copper. Copper is easily collected as its colored bathocuproinedisulfonate chelate anion on 20 mg of chitin from 20 cm3 of aqueous solution at pH 5.0. The reflection absorbance of the chitin phase at 484 nm was measured directly. The calibration curve was linear in the concentration up to 1 μg of copper on 20 mg of chitin. The relative standard deviation was 2.89% for 0.5 μg of copper with 9 measurements. The tolerance limit for VO3- is 200-times in the concentration that of copper, and for Fe3+ and Al3+ it is 500- and 1000-times in the concentration of copper, respectively, when 5 mg of F- is added. Common metal ions, reducing agents and inorganic anions do not interfere in the concentration range of 1000- to 10000- times that of copper. The present method can be applied to the determination of copper in biological standard samples.