Spectrophotometric Determination Of Chromium(Iii) And Chromium(Vi) Using 2-[E)-[{3-[(2-Hydroxybenzylidene) Amino]Phenyl}Imino)Methyl]Phenol

ABSTRACT

The Schiff base ligand, 2-[(E)-[{3--[(2-hydroxybenzylidene)amino]phenyl}imino)methyl]phenol

was synthesized by condensing 1,3-diaminobenzene and 2-hydroxybenzaldehyde in absolute

ethanol. Its Cr(III) and Cr(VI) complexes were equally synthesized. The ligand was

characterized via UV, IR and NMR spectroscopy, whereas the complexes were characterized

based on UV and IR spectroscopy and conductivity values. Stoichiometric studies indicated 1:1

metal to ligand ratio for both complexes. Cr(III) complex absorbed at 1042.56 cm-1 υ(C-O),

532.37 cm-1 υ(Cr-N) and 607.60 cm-1 υ(Cr-O) while the Cr(VI) complex absorbed at 1182 cm-1

υ(C-O), 749.37 cm-1 υ(Cr-O) and 457 cm-1 for υ(Cr-N). Based on UV, IR and NMR studies, the

ligand coordinated to the metals using the nitrogen and oxygen atoms. Spectrophotometric

determination of the metals using the ligand was done at 368 nm for Cr(III) and 465 nm for

Cr(VI).Optimum conditions for complexation and stability were studied and it was shown that

optimum pH for Cr(III) and Cr(VI) were 13.0 and 2.0 respectively. Very few ions such as Co2+,

Cu2+, Mn2+, Mg2+, Fe3+ and Zn2+ interfered with the determination. Beer’s law was obeyed

between 0.02 to 0.14ppm for both metals. The method was successfully applied in the analysis of

steel.

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