Spectrophotometric determination of diphenhydramine. HC1 in pharmaceutical preparations
Maghssoudi, R.H.; Fawzi, A.B.; Moosavi Meerkalaiee, M.A.
Journal - Association of Official Analytical Chemists 60(4): 926-928
1977
ISSN/ISBN: 0004-5756 PMID: 893311 Document Number: 121119
A new spectrophotometric method has been developed for determining diphenhydramine. HC1, based on solvent extraction into chloroform of the complex formed with bromocresol green. The complex solution in chloroform showed maximum absorption at 415 nm and obeyed Beer's law over the concentration range of 3.0-12.0 microgram/ml. The molar absorptivity of the complex was 2.02 x 10(4). Complex formation and extraction was complete and quantitative over the pH range from 2 to 5. The ratio of diphenhydramine to bromocresol green was 1:1. Excipients, coloring matter, flavoring agents, and other substances likely to be present in diphenhydramine preparations do not interfere in the determination. Direct determinations in tablet, capsule, sirup, and lotion preparations were carried out satisfactorily, and the average recovery was 100 +/- 1.0%.