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Najmul Hejaz Azmi SyedCorresponding author Department of Applied Sciences, Chemistry Section, Higher College of Technology, P. O. Box 74, Al-Khuwair-133, Muscat, Sultanate of Oman
Diphenhydramine HClis a weakly fluorescent drug having tertiary amine group forming ion pair complex with eosin Y in dichloromethane at pH 5 in disodium hydrogen phosphate-citric acid buffer solution. The complex formation was the basis for the development of new analytical method for determination of active diphenhydramine in pharmaceutical formulations. The stoichiometric ratio between diphenhydramine and eosin Y was studied by mole ratio method and found to be 2:1. The ion-pair complex showed maximum fluorescence emission intensity at 554 nm with excitation at 259 nm. The linear dynamic range was obtained in the concentration range of 2-22 µg mL-1 with a linear equation of FI = 0.361 + 13.675 C. The apparent Gibb’s free energy (ΔGº) was calculated and found to be -80.783 KJ mol-1, confirmed the feasibility of the reaction. The proposed method was successfully applied to the determination of diphenhydramine HCl in pharmaceutical formulations and in good agreement with the reference method.
Sep 2017 DOI 10.14302/issn.2328-0182.japst-17-1714
Najmul Hejaz Azmi SyedCorresponding author Department of Applied Sciences, Chemistry Section, Higher College of Technology, P. O. Box 74, Al-Khuwair-133, Muscat, Sultanate of Oman
A spectrofluorimetric method has been developed for the determination of imipramine HCl in bulk and commercial dosage forms. The method was based on measuring the fluorescence emission intensity of imipramine-eosin Y ion pair complex (λem = 558 and λex = 319) in dichloroethane at buffer solution (sodium acetate and acetic acid) of pH 4.8. The stoichiometric ratio between imipramine and eosin Y was studied by Job's method of continuous variations and found to be 2:1. Formation constant (Kf) and Gibb’s free energy change (ΔG) were calculated and pointed towards the spontaneous nature of the reaction. A series of variables were studied to optimize the reaction conditions. The proposed method was validated as per ICH guidelines and successfully applied for the determination of active imipramine HCl in commercial dosage forms with high degree of accuracy and precision.