title: Determination of trace amounts of cobalt by solvent extraction--second derivative spectrophotometry.
abstract: A sensitive derivative spectrophotometric method is described for the determination of microamounts of cobalt based on the integration of liquid-liquid separation and reaction, in dichloroethane, of the analyte with 3-(4-phenyl-2-pyridinyl)-5-phenyl-1,2,4-triazine (PPT) and 2,4,6-trinitro-phenol (picric acid). Cobalt was thus determined in the range 7.2-500 ng/ml. The method has a high selectivity with a detection limit of 2.2 ng/ml. The relative standard deviations were 3.2 and 1.5% for 20 and 100 ng/ml cobalt, respectively. The proposed method was applied to the determination of the analyte in vitamins.
authors.affiliation: Department of Chemistry, Faculty of Sciences, University of Chile, Las Palmeras 3425, Santiago, Chile.
authors.forename: M I
authors.initials: MI
authors.lastname: Toral
authors.forename: P
authors.initials: P
authors.lastname: Richter
authors.forename: L
authors.initials: L
authors.lastname: Silva