Asian Journal of Chemistry Vol. 20, No. 2 (2008), 1402-1410 Derivative Spectrophotometric Determination of Uranium(VI) using 2-Hydroxy-3-methoxybenzaldehydeisonicotinoyl- hydrazone Reagent M. RAMESWARA RAO, K. HARI†, N. DEVANNA and K.B. CHANDRASEKHAR* Department of Chemistry, Jawaharlal Nehru Technological University College of Engineering (Autonomous), Anantapur-515 002, India E-mail: chandrasekhar_kb@yahoo.co.in A 1:1 (M:L) yellow coloured water-soluble complex of U(VI) is formed with 2-hydroxy-3-methoxybenzaldehyde- isonicotinoylhydrazone (HMBIH) in acidic buffer solution. The reaction between U(VI)-HMBIH is instantaneous at pH 4.0 and the absorbance remains constant for more than 2 h. The molar absorptivity and sandell's sensitivity is 1.05 × 10 4 L mol -1 cm -1 and 0.0238 μg cm 2 , respectively at λmax 374 nm. Beer's law obeyed in the concentration range of 1.19-11.9 μg/mL. The stability constant of U(VI)-HMBIH complex is 2.08 × 10 6 . The first and second order derivative spectro- photometric determination of U(VI) was carried out by mea- suring peak height technique at 436 and 441 nm, respectively. This method has been satisfactorily applied for the deter- mination of U(VI) in rock and synthetic samples. The effect of various diverse ions also studied. Key Words: 2-Hydroxy-3-methoxybenzaldehydeisonicoti- noylhydrazone, Derivative spectrophotometry, U(VI) determination. INTRODUCTION The potential application of hydrazone derivatives for the spectropho- tometric determination of metal ions has been reviewed by Singh et al. 1 . The spectrophotometric determinations of uranium by using hydrazones are not used much 2,3 . In the light of good analytical characteristic of hydrazones, here in we report the synthesis, characterization and analyti- cal properties of 2-hydroxy-3-methoxybenzaldehydeisonicotinoylhydra- zone (HMBIH). In continuation of our previous work, herein we report zero, first and second order derivative spectrophotometric determination of U(VI) in aqueous medium. Derivative spectrophotometric methods for the determination of metal ions 4-7 are not exploited much. †Department of Chemical Engineering, Jawaharlal Nehru Technological University College of Engineering (Autonomous), Anantapur-515 002, India.