Abstract UV- and second derivative spectrophotometric and high-performance liquid chromatographic (HPLC) methods for the determination of losartan in tablets have been developed. For UV-spectropho-tometric method, absorbances of the standard solutions were measured at 206.6 nm. For second deriv-ative spectrophotometric method, the distance between two extremum values (peak-to-peak amplitudes), 219.6 nm and 228.8 nm, were measured in the second order derivative spectra of standard solutions. Calibration curves were constructed by plotting d2AJd'k2 values against concentrations. These wave-lengths were selected depend on obtained the maximum values. HPLC method was carried out on C18 column using the mobile phase consisted of a mixture of acetonitrile and phosphate buffer (pH=3.8, 40:60, v/v) and column eluate was monitored at 225 nm. The three methods were applied to determine of losartan in tablets. Özet Losartanin tabletlerde miktar tayini için UV, 2. türev spektrofotometrik ve yüksek performansli sivi kromatografik (HPLC) yöntemler gelistirildi. UV spektrofotometrik yöntem için standart çözeltilerin absorbanslari 206.6 nm’de ölçüldü. 2. türev spekrofotometrik yöntem için iki ekstremum deger arasindaki aralik; 219.6 nm ve 228.8 nm’de standart çözeltilerin 2. türev spektrumlari alindi. Kalibrasyon egrileri konsantrasyona karsi d2AJdk2 degerlerinin grafige geçirilmesiyle elde edildi. Bu dalga boylan elde edilen maksimum degerlere bagli olarak seçildi. HPLC yöntemi asetonitril ve fosfat tamponu (pH=3.8, 40:60, h/h) karisimindan olusan bir mobil fazin kullanildigi C18 kolonunda uygulandi ve kolon elüati 225 nm’de gözlendi. Her 3 yöntem tabletlerde losartanin tayinine uygulandi.

Keywords: Losartan, UV-spectrophotometry, Derivative spectrophotometry, HPLC