The interaction of piroxicam with some metal ions in aqueous solution

Abstract

The interaction of various metal ions, such as Co(II), Cu(II), La(III), Ce(III), Y(III) and Al(III), with piroxicam in aqueous solution has been studied by spectroscopic methods. The interaction of the metal ions with HMBDC (4-hydroxy-2-methyl-1,2λ-benzothiazine-1,1-dioxide-3-methyl-carboxylate) has also been studied for comparison. It was found that Al(III) and Y(III) ions interact significantly with both piroxicam and HMBDC to form 1:1 complexes in aqueous solution. The stability constants of the complexes have been determined at μ → 0. The thermodynamic parameters for the complex formations have also been calculated from the Gibbs-Helmholtz plot. On the basis of the spectroscopic and thermodynamic evidence, the binding sites of piroxicam and HMBDC to the metal ions are suggested.