A new spectrofluorimetric method for the determination of lisinopril in tablets

An accurate and precise spectrofluorimetric method is presented for the determination of lisinopril based on the formation of a derivative formed with 7-chloro-4-nitrobenzofurazan. The derivatization reaction proceeds quantitatively at pH 8.5-9.0 and 60 degrees C in 70 min when the molar ratio of reagent to the drug is 170. After the extraction with ethyl acetate the fluorescence intensity of the derivative was measured at 528 nm with excitation at 465 nm. Calibration graph is rectilinear over the range of 50-1000 ng/ml with detection and determination limits of 20 and 50 ng/ml, respectively. The regression equation is I(f) = 0.198C-0.299 (r = 0.9999). The method was applied to the commercially available tablets and the results were statistically compared with those obtained by official HPLC method.