Voltammetric and Spectrophotometric Determination

Voltammetric and Spectrophotometric Determination

Zajel / An-Najah National University

Hala Hasan Hafiz Arafat Simple and sensitive spectrophotometric and voltammetric methods wt,re developed for the determination of nizatidine (NIZ) in pharmaceutical fo mulations. NIZ tends to form stable coloured ion- pair complexes with acid dyes, e.g. bromothymol blue (BTB) and bromocresol green (BCG). TI ,e methods are based on the reaction of the drug with BCG or BTB to gi e - yellow coloured ion-pair complex. The produced complexes are exiracted from the aqueous phase to dichloromethane and measured sp ~ctrophotometrically at 416nm. The molar absorpitivities were found to be 2.12 x 101 and 3.0 X104 1 mol-1. cm-1. using BCG and BTB, respectively. Optimization of different experimental conditions is described. Rectilinear ca ibration curves were obtained in the concentration ranges 0.2-8.0 and 0.1 - ).6 ppm of drug for BCG and BTB, respectively. The detection limits were found to be 0.2 and 0.1 ppm for BCG and BTB, respectively. A differential - pulse adsorptive stripping voltammetric (DPA (CSV) technique using hanging mercury drop electrode (HMDE) at pH 3.. is also described. The effect of pH, electrolyte, scan rate, pulse an plitude and the presence of some excipients were studied using DP A,'CSV. The calibration graph for determination of NIZ was linear in the ra ~oe 0.01 - 0.33 ppm with relative standard deviation of 1.46% and dc ectlou limit of 0.003 ppln. Applications of the suggested methods for determination of NIZ in N ~ /-raw material and tablets are presented and compared with other re;~orted methods. In comparison with other reported methods, the proposed methods especially the voltammetric method are found to be simple, rapid, le, i laborious, cheap, sensitive and accurate with excellent recovery . Hala Hasan Hafiz Arafat Supervisors Prof. Ali Z. Abu Zuhri Dr. Nidal Za'tar June 1999