Anion exchange separation by DEAE-cellulose and spectrophotometric determination of copper, gold and palladium in dental alloys

Abstract

A combined method of ion-exchange separation and spectrophotometry was described for determination of copper, gold and palladium in dental alloys. The sample of about 50 mg was taken and treated with a few ml of nitric acid and then aqua regia and diluted. The silver chloride precipitated was filtered off, and the filtrate was diluted to a definite volume to give ca. 0.2 M in hydrochloric acid. One ml aliquot was taken and mixed with 19 ml of acetic acid and transferred to a column (φ 1×6 cm) of one gram of weakly basic anion exchanger diethylaminoethyl cellulose in the chloride form.Au(III) and Pd(II) were retained on the column, while Cu(II) was easily removed from the column with 60 ml of acetic acid-0.5 M hydrochloric acid (9:1). Subsequently, Au(III) was eluted from the column with 50 ml of acetic acid-2 M hydrochloric acid (9:1) and finally Pd(II) was recovered by elution with 50 ml of acetone-6 M hydrochloric acid (9:1). An aliquot of each effluent was taken and the metal ion was determined spectrophotometrically by use of diethyldithiocarbamate for copper, rhodamine B for gold and p-nitrosodiphenylamine for palladium, respectively.The proposed method is reasonably simple and can be applied successfully to the determination of copper, gold and palladium in a variety of dental alloys.