Syed Najmul Hejaz Azmi, Aisha Al-Mahroqi, Khoula Al-Mamari, Shaima Al-Shukaili, Validated Analytical Spectrofluorimetric Method for Quantitation of Diphenhydramine HCl in Commercial Dosage Forms, Journal of New Developments in Chemistry, Volume 1, Issue 4, 2018, Pages 12-26, ISSN 2377-2549, https://doi.org/10.14302/issn.2377-2549.jndc-18-2220.
(https://www.ijn-medicalarticles.info/new-developments-in-chemistry/article/validated-analytical-spectrofluorimetric-method-for-quantitation-of-diphenhydramine-hcl-in-commercial-dosage-forms-810)
Abstract: Diphenhydramine HCl is a weakly fluorescent drug having a tertiary amine group forming an 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 a 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, confirming 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.
Keywords: diphenhydramine HCl; spectrofluorimetry; validation; pharmaceutical formulations