Spectrophotometric, septrofluorimetric and LC determination of lisinopril

Three methods are described for the determination of lisinopril in the pharmaceutical tablets. The spectrophotometric method depends on the reaction of the lisinopril with sodium hypochlorite and phenyl hydrazine to form a condensation product measured at 362 nm. The spectrophotometric method was extended to develop a stability indicating method. The spectrofluorimetric method depends on reaction of the lisinopril with o-phthalaldehyde in the presence of 2-mercaptoethanol in borate buffer pH 9.5. The fluorescence of the reaction product was measured upon excitation at a maximum of 340 nm with emission wavelength at 455 nm. The HPLC method depends on using Hypersil silica column with a mobile phase consisting of methanol-water-triethylamine (50:50:0.1 v/v) and the pH was adjusted to 2.6 with 0.1 N perchloric acid. Quantitation was achieved with UV detection at 210 nm based on peak area.