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

摘要

A collection method for anionic species on protonated chitin has been applied to the solid-phase spectrophotometric determination of trace copper. Copper is easily collect ed as its colored bathocuproinedisulfonate chelate anion on 20 mg of chitin from 20 cm~3 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 l 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 VO_3~- is 200-times in the concen- tration that of copper, and for Fe~(3+) and Al~(3+) it is 500- and 1000-times in the concentra tion 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 l000- to l0000- times that of copper. The present method can be applied to the determination of copper in biological standard samples.