Spectrophotometric determination of nickel(II) using 5-Br-PADAP and N-hydroxy -N,N' -diphenylbenzamidine

School of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur-492 010, India
E-mail: debmanas@yahoo.com
Manuscript received 17 October 2003, accepted 17 March 2004

A sensitive and simple spectrophutumetric method for determination of Ni^II with 2-[(5-hromo-2-pyridylazo)]-5-
diethylaminophenol (5-Br-PADAP) and N-hydroxy-N,N' -diphenylhenzamidine (HDPBA) is described. The Ni^II-2-[(5-bromo-
2-pyridylazo)]-5-diethylaminophenol (5-Br-PADAP) complex is extracted with N-hydroxy-N,N' -diphenylbenzamidine
(HDPBA) in chloroform at pH range 4.0-6.0 to give red colour complex. Extracted complex shows λ_max at 530 nm. Procedure
is checked by finding relative standard deviation (RSD, n = 10) value for solutions each containing 2.0 µg mI^-1 Ni^II
and the RSD value of the procedure is found to he 1.6%. The system obeyed Beer's law up to 0.5 (.lg ml-1 of nickel and the
identification limit of the method is 7.4 x 10-¹⁰ g ml^-1 on a three times the standard deviation of the blank absorbance basis.
The Sandell's sensitivity and molar absorptivity of the complex are 0.00056 µg ml^-1 and 1.04 x 10⁵ dm³ mol^-1 cm^-1 respectively.
The effect of foreign ions and other experimental variables are studied.