摘要：Colorimetric determination of diphenhydramine hydrochloride and diphenhydramine salicylate in mixed pharmaceutical preparations was examined and highly selective and precise method was established. Diphenhydramine was oxidized by potassium dichromate in acidic medium to produce benzophenone which reacted with 2, 4-dinitrophenylhydrazine to from benzophenone-2, 4-dinitrophenylhydrazone which colored red by the addition of an alkali agent. The colored solution had absorption maximum at 475 nm. Presence of phenacetine, acetaminophene, diphenylpyraline hydrochloride, Pandoryl-P, Tonzylamine hydrochloride, and Mebhydroline Napadisylate interfered in this reaction but phenacetine and acetaminophene could be eliminated by extraction with hexane in basic or acidic medium.
