Solid-Liquid Separation after Liquid-Liquid Extraction. -Spectrophotometric Determination of Copper after Extraction of Its 5，7- dichloro-oxinate and 5，7-dibromo-oxinate with Molten N aphthalene-

摘要

A spectrophotometric method for the determination of μg amounts of copperin sample solution is presented. Copper reacts with oxine， 2-methyl-oxine， 5,7-dichloro-oxineand 5,7-dibromo-oxine to form water-insoluble colored complexes.These complexes are directly extracted into mo1ten naphthalene.The extracted mixture of copper complex and naphthalene is separated fromaqueous solution by decantation， dried on a fi1ter paper and dissolved indimethylformamide. The absorbance of the solution is measured at a givenwavelength of 420 nm against the reagent blank and μg amounts of copper isdetermined spectrophotometrically. The other factors such as pH， amounts ofreagent，naphthalene and diverse salts are studied. The molar absorptivity，sensitivity and relative standard deviation are evaluated.