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Journal of Pharmaceutical and Applied Chemistry
An International Journal


Volumes > Vol. 5 > No. 2


Potentiometric and Conductometric Studies on Enalapril Complexes of some Metal Ions and its Determination in Tablet Dosage Form

PP: 97-106
Hussein M.El-Sagher,
Ten metal ions viz, Fe(III), Cr(III), La(II), Th(IV), Co(II), Mn(II), Pd(II), Ti(II), Sr(II) and Zr(II), were selected to elucidate the interaction of these metal ions with Enalapril (ENA) using potentiometric and conductometric methods. The ionization constant of the ligand and stability constants of the complexes formed have been tabulated at 250.1Co and 0.o5 mol dm-3 ionic strength of NaNO3 aqueous solution. Complexes of 1:1, 1:2 and/or 1:3 metal to ligand ratios are formed depending on the nature of the ligand or metal ions. As well as, the stoichiometry of complexes confirmed by conductometric method. Also, simple, precise, rapid and low-cost potentiometric method for enalapril determination in pure form and tablets is proposed. Enalapril present in tablets containing known quantity of drug was potentiometrically titrated with aqueous solution at 0.1mol dm-3 of NaOH using a combined glass pH electrode. The detection limit was detected from 0.009 mg/ml (with the standard deviation, SD=1.58, correlation coefficient, R=0.9785 (n=5). Linear concentration ranges from 0.37 to 22.6 mg/ml can be determined successfully. The standard addition method was used to determine ENA in pure solutions and tablets with satisfactory results. No interferences were observed in the presence of common components of the tablets. Recovery of enalapril from various tablet dosage formulations range from 97.25 to 100.4%.

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