SELECTIVE PRECONCENTRATION AND DETERMINATION OF COBALT(II) USING N,N′-BIS(2-HYDROXY-5-BROMO-BENZYL)-1,2-DIAMINOPROPANE

ABSTRACT

The present work describes a selective, rapid, and economical method for the determination of cobalt using N,N′-bis(2-hydroxy-5-bromo-benzyl)-1,2-diaminopropane (HBDAP). The investigation included a study of the characteristics that are essential for solvent extraction and preconcentration of cobalt for determination by FAAS (Flame atomic absorption spectrometry) and also the organic phase loaded with Co(II) from aqueous phase was stripped in one stage by using different mineral acid solutions. It was found that stripping efficiency was quantitative in case of HNO₃. Furthermore, a highly sensitive, selective, and rapid spectrophotometric method is described for the determination of trace amounts of Co(II) by HBDAP. This compound reacts with cobalt(II) in the range of pH 6–10 to produce a greenish yellow complex (2 : 3 molar ratio of Co(II)/HBDAP) soluble in chloroform. The complex obeys Beer's law from 0.7 to 7.25 µg mL⁻¹ with an optimum range. The relative standard deviations were 0.05% (13 samples, each containing 4.2 µg mL⁻¹ Co(II)). The precision was determined from 25 results obtained for 1 × 10⁻⁵ M Co(II); the mean value of a Co(II) was 1.03 × 10⁻⁵ M with a standard deviation of 2.35 × 10⁻⁷ M Co(II).

Keywords:

• Cobalt(II) determination
• Preconcentration
• FAAS
• Spectrophotometry
• Solvent extraction
• N,N′-bis(2-hydroxy-5-bromo-benzyl)-1,2-diaminopropane

ACKNOWLEDGMENTS

This work was supported by Balıkesir University Research Fund (Project No: 99/5). One of the authors (Derya KARA) thanks to the National Doctorate Scholarship (TÜBİTAK) for the fellowship.