Titrimetric assay of lisinopril in aqueous and non-aqueous media

four simple titrimetric procedures are described for the determination of lisinopril (lnp) in bulk and in pharmaceuticals based on the neutralization of basic-amino and acidic carboxylic acid groups present in lnp. method a is based on the neutralization of basic amino groups using perchloric acid as titrant in anhydrous acetic acid medium. method b, method c and method d are based on neutralization of carboxylic acid group using naoh, sodium methoxide and methanolic koh, as titrants, respectively. method a is applicable over 2.0-20.0 mg range and the calculations are based in the molar ratio of 1:2 (lnp:hclo4). method b, method c and method d are applicable over 2.0-20.0 mg, 1.0-10.0 mg and 5.0-15.0 mg range, respectively, and their respective molar ratios are 1:1 (lnp:naoh), 1:2 (lnp:ch3ona) and 1:1 (lnp:koh). intraday and inter day accuracy and precision of the methods were evaluated and the results showed intra- and inter-day precision less than 2.7% (rsd), and accuracy of < 2.5 % (re). the developed methods were applied to determine lnp in tablets and the results were validated statistically by comparing the results with those of the reference method by applying the student's t-test and f-test. the accuracy was further ascertained by recovery studies via standard addition technique. no interferences from common tablet exipients was observed.