Photoacoustic Microdetermination of Copper in Copper Alloys by Use of Ring Oven Techniquet

Abstract

Copper alloys, about 1 or 2 mg, were dissolved with a few drops of 2 moldm^-3 nitric acid, and diluted to 10 cm³ with distilled water. An aliquot this solution (4 mm³) was dropped on the center of filter paper (Toyo No.51 A) on a ring oven at 120°C. Copper(II) was separated from coexistent metal ions in an atmosphere of hydrogen sulfide by using ring oven technique. Copper(II) diethyldithiocarbamat (Cu-DDTC) complex was formed with 1% Na-DDTC solution. Determination of copper(II) was made by using the photoacoustic (PA) intensity at 433.0 nm, the maximum wavelength of Cu(II)-DDTC complex spectrum. The calibration curve was obtained by using At= -log{1-(St/SO}²), where At is absorbancy, St is PA signal intensity of the sample and Sb is PA signal intensity of a black filter paper (Toyo No.131-B). The determination range of copper(II) was from 0.1 to 1.4 /μg. The coefficient of variation obtained for ten samples was ±2%.